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configs/ltxv-13b-0.9.7-dev.yaml

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+pipeline_type: multi-scale
+checkpoint_path: "ltxv-13b-0.9.7-dev.safetensors"
+downscale_factor: 0.6666666
+spatial_upscaler_model_path: "ltxv-spatial-upscaler-0.9.7.safetensors"
+stg_mode: "attention_values" # options: "attention_values", "attention_skip", "residual", "transformer_block"
+decode_timestep: 0.05
+decode_noise_scale: 0.025
+text_encoder_model_name_or_path: "PixArt-alpha/PixArt-XL-2-1024-MS"
+precision: "bfloat16"
+sampler: "from_checkpoint" # options: "uniform", "linear-quadratic", "from_checkpoint"
+prompt_enhancement_words_threshold: 120
+prompt_enhancer_image_caption_model_name_or_path: "MiaoshouAI/Florence-2-large-PromptGen-v2.0"
+prompt_enhancer_llm_model_name_or_path: "unsloth/Llama-3.2-3B-Instruct"
+stochastic_sampling: false
+
+first_pass:
+  guidance_scale: [1, 1, 6, 8, 6, 1, 1]
+  stg_scale: [0, 0, 4, 4, 4, 2, 1]
+  rescaling_scale: [1, 1, 0.5, 0.5, 1, 1, 1]
+  guidance_timesteps: [1.0, 0.996,  0.9933, 0.9850, 0.9767, 0.9008, 0.6180]
+  skip_block_list: [[], [11, 25, 35, 39], [22, 35, 39], [28], [28], [28], [28]]
+  num_inference_steps: 30
+  skip_final_inference_steps: 3
+  cfg_star_rescale: true
+
+second_pass:
+  guidance_scale: [1]
+  stg_scale: [1]
+  rescaling_scale: [1]
+  guidance_timesteps: [1.0]
+  skip_block_list: [27]
+  num_inference_steps: 30
+  skip_initial_inference_steps: 17
+  cfg_star_rescale: true

configs/ltxv-2b-0.9.1.yaml

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+pipeline_type: base
+checkpoint_path: "ltx-video-2b-v0.9.1.safetensors"
+guidance_scale: 3
+stg_scale: 1
+rescaling_scale: 0.7
+skip_block_list: [19]
+num_inference_steps: 40
+stg_mode: "attention_values" # options: "attention_values", "attention_skip", "residual", "transformer_block"
+decode_timestep: 0.05
+decode_noise_scale: 0.025
+text_encoder_model_name_or_path: "PixArt-alpha/PixArt-XL-2-1024-MS"
+precision: "bfloat16"
+sampler: "from_checkpoint" # options: "uniform", "linear-quadratic", "from_checkpoint"
+prompt_enhancement_words_threshold: 120
+prompt_enhancer_image_caption_model_name_or_path: "MiaoshouAI/Florence-2-large-PromptGen-v2.0"
+prompt_enhancer_llm_model_name_or_path: "unsloth/Llama-3.2-3B-Instruct"
+stochastic_sampling: false

configs/ltxv-2b-0.9.5.yaml

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+pipeline_type: base
+checkpoint_path: "ltx-video-2b-v0.9.5.safetensors"
+guidance_scale: 3
+stg_scale: 1
+rescaling_scale: 0.7
+skip_block_list: [19]
+num_inference_steps: 40
+stg_mode: "attention_values" # options: "attention_values", "attention_skip", "residual", "transformer_block"
+decode_timestep: 0.05
+decode_noise_scale: 0.025
+text_encoder_model_name_or_path: "PixArt-alpha/PixArt-XL-2-1024-MS"
+precision: "bfloat16"
+sampler: "from_checkpoint" # options: "uniform", "linear-quadratic", "from_checkpoint"
+prompt_enhancement_words_threshold: 120
+prompt_enhancer_image_caption_model_name_or_path: "MiaoshouAI/Florence-2-large-PromptGen-v2.0"
+prompt_enhancer_llm_model_name_or_path: "unsloth/Llama-3.2-3B-Instruct"
+stochastic_sampling: false

configs/ltxv-2b-0.9.6-dev.yaml

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+pipeline_type: base
+checkpoint_path: "ltxv-2b-0.9.6-dev-04-25.safetensors"
+guidance_scale: 3
+stg_scale: 1
+rescaling_scale: 0.7
+skip_block_list: [19]
+num_inference_steps: 40
+stg_mode: "attention_values" # options: "attention_values", "attention_skip", "residual", "transformer_block"
+decode_timestep: 0.05
+decode_noise_scale: 0.025
+text_encoder_model_name_or_path: "PixArt-alpha/PixArt-XL-2-1024-MS"
+precision: "bfloat16"
+sampler: "from_checkpoint" # options: "uniform", "linear-quadratic", "from_checkpoint"
+prompt_enhancement_words_threshold: 120
+prompt_enhancer_image_caption_model_name_or_path: "MiaoshouAI/Florence-2-large-PromptGen-v2.0"
+prompt_enhancer_llm_model_name_or_path: "unsloth/Llama-3.2-3B-Instruct"
+stochastic_sampling: false

configs/ltxv-2b-0.9.6-distilled.yaml

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+pipeline_type: base
+checkpoint_path: "ltxv-2b-0.9.6-distilled-04-25.safetensors"
+guidance_scale: 1
+stg_scale: 0
+rescaling_scale: 1
+num_inference_steps: 8
+stg_mode: "attention_values" # options: "attention_values", "attention_skip", "residual", "transformer_block"
+decode_timestep: 0.05
+decode_noise_scale: 0.025
+text_encoder_model_name_or_path: "PixArt-alpha/PixArt-XL-2-1024-MS"
+precision: "bfloat16"
+sampler: "from_checkpoint" # options: "uniform", "linear-quadratic", "from_checkpoint"
+prompt_enhancement_words_threshold: 120
+prompt_enhancer_image_caption_model_name_or_path: "MiaoshouAI/Florence-2-large-PromptGen-v2.0"
+prompt_enhancer_llm_model_name_or_path: "unsloth/Llama-3.2-3B-Instruct"
+stochastic_sampling: true

configs/ltxv-2b-0.9.yaml

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+pipeline_type: base
+checkpoint_path: "ltx-video-2b-v0.9.safetensors"
+guidance_scale: 3
+stg_scale: 1
+rescaling_scale: 0.7
+skip_block_list: [19]
+num_inference_steps: 40
+stg_mode: "attention_values" # options: "attention_values", "attention_skip", "residual", "transformer_block"
+decode_timestep: 0.05
+decode_noise_scale: 0.025
+text_encoder_model_name_or_path: "PixArt-alpha/PixArt-XL-2-1024-MS"
+precision: "bfloat16"
+sampler: "from_checkpoint" # options: "uniform", "linear-quadratic", "from_checkpoint"
+prompt_enhancement_words_threshold: 120
+prompt_enhancer_image_caption_model_name_or_path: "MiaoshouAI/Florence-2-large-PromptGen-v2.0"
+prompt_enhancer_llm_model_name_or_path: "unsloth/Llama-3.2-3B-Instruct"
+stochastic_sampling: false

inference.py

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+import argparse
+import os
+import random
+from datetime import datetime
+from pathlib import Path
+from diffusers.utils import logging
+from typing import Optional, List, Union
+import yaml
+
+import imageio
+import json
+import numpy as np
+import torch
+from safetensors import safe_open
+from PIL import Image
+from transformers import (
+    T5EncoderModel,
+    T5Tokenizer,
+    AutoModelForCausalLM,
+    AutoProcessor,
+    AutoTokenizer,
+)
+from huggingface_hub import hf_hub_download
+
+from ltx_video.models.autoencoders.causal_video_autoencoder import (
+    CausalVideoAutoencoder,
+)
+from ltx_video.models.transformers.symmetric_patchifier import SymmetricPatchifier
+from ltx_video.models.transformers.transformer3d import Transformer3DModel
+from ltx_video.pipelines.pipeline_ltx_video import (
+    ConditioningItem,
+    LTXVideoPipeline,
+    LTXMultiScalePipeline,
+)
+from ltx_video.schedulers.rf import RectifiedFlowScheduler
+from ltx_video.utils.skip_layer_strategy import SkipLayerStrategy
+from ltx_video.models.autoencoders.latent_upsampler import LatentUpsampler
+
+MAX_HEIGHT = 720
+MAX_WIDTH = 1280
+MAX_NUM_FRAMES = 257
+
+logger = logging.get_logger("LTX-Video")
+
+
+def get_total_gpu_memory():
+    if torch.cuda.is_available():
+        total_memory = torch.cuda.get_device_properties(0).total_memory / (1024**3)
+        return total_memory
+    return 0
+
+
+def get_device():
+    if torch.cuda.is_available():
+        return "cuda"
+    elif torch.backends.mps.is_available():
+        return "mps"
+    return "cpu"
+
+
+def load_image_to_tensor_with_resize_and_crop(
+    image_input: Union[str, Image.Image],
+    target_height: int = 512,
+    target_width: int = 768,
+    just_crop: bool = False,
+) -> torch.Tensor:
+    """Load and process an image into a tensor.
+
+    Args:
+        image_input: Either a file path (str) or a PIL Image object
+        target_height: Desired height of output tensor
+        target_width: Desired width of output tensor
+        just_crop: If True, only crop the image to the target size without resizing
+    """
+    if isinstance(image_input, str):
+        image = Image.open(image_input).convert("RGB")
+    elif isinstance(image_input, Image.Image):
+        image = image_input
+    else:
+        raise ValueError("image_input must be either a file path or a PIL Image object")
+
+    input_width, input_height = image.size
+    aspect_ratio_target = target_width / target_height
+    aspect_ratio_frame = input_width / input_height
+    if aspect_ratio_frame > aspect_ratio_target:
+        new_width = int(input_height * aspect_ratio_target)
+        new_height = input_height
+        x_start = (input_width - new_width) // 2
+        y_start = 0
+    else:
+        new_width = input_width
+        new_height = int(input_width / aspect_ratio_target)
+        x_start = 0
+        y_start = (input_height - new_height) // 2
+
+    image = image.crop((x_start, y_start, x_start + new_width, y_start + new_height))
+    if not just_crop:
+        image = image.resize((target_width, target_height))
+    frame_tensor = torch.tensor(np.array(image)).permute(2, 0, 1).float()
+    frame_tensor = (frame_tensor / 127.5) - 1.0
+    # Create 5D tensor: (batch_size=1, channels=3, num_frames=1, height, width)
+    return frame_tensor.unsqueeze(0).unsqueeze(2)
+
+
+def calculate_padding(
+    source_height: int, source_width: int, target_height: int, target_width: int
+) -> tuple[int, int, int, int]:
+
+    # Calculate total padding needed
+    pad_height = target_height - source_height
+    pad_width = target_width - source_width
+
+    # Calculate padding for each side
+    pad_top = pad_height // 2
+    pad_bottom = pad_height - pad_top  # Handles odd padding
+    pad_left = pad_width // 2
+    pad_right = pad_width - pad_left  # Handles odd padding
+
+    # Return padded tensor
+    # Padding format is (left, right, top, bottom)
+    padding = (pad_left, pad_right, pad_top, pad_bottom)
+    return padding
+
+
+def convert_prompt_to_filename(text: str, max_len: int = 20) -> str:
+    # Remove non-letters and convert to lowercase
+    clean_text = "".join(
+        char.lower() for char in text if char.isalpha() or char.isspace()
+    )
+
+    # Split into words
+    words = clean_text.split()
+
+    # Build result string keeping track of length
+    result = []
+    current_length = 0
+
+    for word in words:
+        # Add word length plus 1 for underscore (except for first word)
+        new_length = current_length + len(word)
+
+        if new_length <= max_len:
+            result.append(word)
+            current_length += len(word)
+        else:
+            break
+
+    return "-".join(result)
+
+
+# Generate output video name
+def get_unique_filename(
+    base: str,
+    ext: str,
+    prompt: str,
+    seed: int,
+    resolution: tuple[int, int, int],
+    dir: Path,
+    endswith=None,
+    index_range=1000,
+) -> Path:
+    base_filename = f"{base}_{convert_prompt_to_filename(prompt, max_len=30)}_{seed}_{resolution[0]}x{resolution[1]}x{resolution[2]}"
+    for i in range(index_range):
+        filename = dir / f"{base_filename}_{i}{endswith if endswith else ''}{ext}"
+        if not os.path.exists(filename):
+            return filename
+    raise FileExistsError(
+        f"Could not find a unique filename after {index_range} attempts."
+    )
+
+
+def seed_everething(seed: int):
+    random.seed(seed)
+    np.random.seed(seed)
+    torch.manual_seed(seed)
+    if torch.cuda.is_available():
+        torch.cuda.manual_seed(seed)
+    if torch.backends.mps.is_available():
+        torch.mps.manual_seed(seed)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Load models from separate directories and run the pipeline."
+    )
+
+    # Directories
+    parser.add_argument(
+        "--output_path",
+        type=str,
+        default=None,
+        help="Path to the folder to save output video, if None will save in outputs/ directory.",
+    )
+    parser.add_argument("--seed", type=int, default="171198")
+
+    # Pipeline parameters
+    parser.add_argument(
+        "--num_images_per_prompt",
+        type=int,
+        default=1,
+        help="Number of images per prompt",
+    )
+    parser.add_argument(
+        "--image_cond_noise_scale",
+        type=float,
+        default=0.15,
+        help="Amount of noise to add to the conditioned image",
+    )
+    parser.add_argument(
+        "--height",
+        type=int,
+        default=704,
+        help="Height of the output video frames. Optional if an input image provided.",
+    )
+    parser.add_argument(
+        "--width",
+        type=int,
+        default=1216,
+        help="Width of the output video frames. If None will infer from input image.",
+    )
+    parser.add_argument(
+        "--num_frames",
+        type=int,
+        default=121,
+        help="Number of frames to generate in the output video",
+    )
+    parser.add_argument(
+        "--frame_rate", type=int, default=30, help="Frame rate for the output video"
+    )
+    parser.add_argument(
+        "--device",
+        default=None,
+        help="Device to run inference on. If not specified, will automatically detect and use CUDA or MPS if available, else CPU.",
+    )
+    parser.add_argument(
+        "--pipeline_config",
+        type=str,
+        default="configs/ltxv-13b-0.9.7-dev.yaml",
+        help="The path to the config file for the pipeline, which contains the parameters for the pipeline",
+    )
+
+    # Prompts
+    parser.add_argument(
+        "--prompt",
+        type=str,
+        help="Text prompt to guide generation",
+    )
+    parser.add_argument(
+        "--negative_prompt",
+        type=str,
+        default="worst quality, inconsistent motion, blurry, jittery, distorted",
+        help="Negative prompt for undesired features",
+    )
+
+    parser.add_argument(
+        "--offload_to_cpu",
+        action="store_true",
+        help="Offloading unnecessary computations to CPU.",
+    )
+
+    # video-to-video arguments:
+    parser.add_argument(
+        "--input_media_path",
+        type=str,
+        default=None,
+        help="Path to the input video (or imaage) to be modified using the video-to-video pipeline",
+    )
+
+    parser.add_argument(
+        "--strength",
+        type=float,
+        default=1.0,
+        help="Editing strength (noising level) for video-to-video pipeline.",
+    )
+
+    # Conditioning arguments
+    parser.add_argument(
+        "--conditioning_media_paths",
+        type=str,
+        nargs="*",
+        help="List of paths to conditioning media (images or videos). Each path will be used as a conditioning item.",
+    )
+    parser.add_argument(
+        "--conditioning_strengths",
+        type=float,
+        nargs="*",
+        help="List of conditioning strengths (between 0 and 1) for each conditioning item. Must match the number of conditioning items.",
+    )
+    parser.add_argument(
+        "--conditioning_start_frames",
+        type=int,
+        nargs="*",
+        help="List of frame indices where each conditioning item should be applied. Must match the number of conditioning items.",
+    )
+
+    args = parser.parse_args()
+    logger.warning(f"Running generation with arguments: {args}")
+    infer(**vars(args))
+
+
+def create_ltx_video_pipeline(
+    ckpt_path: str,
+    precision: str,
+    text_encoder_model_name_or_path: str,
+    sampler: Optional[str] = None,
+    device: Optional[str] = None,
+    enhance_prompt: bool = False,
+    prompt_enhancer_image_caption_model_name_or_path: Optional[str] = None,
+    prompt_enhancer_llm_model_name_or_path: Optional[str] = None,
+) -> LTXVideoPipeline:
+    ckpt_path = Path(ckpt_path)
+    assert os.path.exists(
+        ckpt_path
+    ), f"Ckpt path provided (--ckpt_path) {ckpt_path} does not exist"
+
+    with safe_open(ckpt_path, framework="pt") as f:
+        metadata = f.metadata()
+        config_str = metadata.get("config")
+        configs = json.loads(config_str)
+        allowed_inference_steps = configs.get("allowed_inference_steps", None)
+
+    vae = CausalVideoAutoencoder.from_pretrained(ckpt_path)
+    transformer = Transformer3DModel.from_pretrained(ckpt_path)
+
+    # Use constructor if sampler is specified, otherwise use from_pretrained
+    if sampler == "from_checkpoint" or not sampler:
+        scheduler = RectifiedFlowScheduler.from_pretrained(ckpt_path)
+    else:
+        scheduler = RectifiedFlowScheduler(
+            sampler=("Uniform" if sampler.lower() == "uniform" else "LinearQuadratic")
+        )
+
+    text_encoder = T5EncoderModel.from_pretrained(
+        text_encoder_model_name_or_path, subfolder="text_encoder"
+    )
+    patchifier = SymmetricPatchifier(patch_size=1)
+    tokenizer = T5Tokenizer.from_pretrained(
+        text_encoder_model_name_or_path, subfolder="tokenizer"
+    )
+
+    transformer = transformer.to(device)
+    vae = vae.to(device)
+    text_encoder = text_encoder.to(device)
+
+    if enhance_prompt:
+        prompt_enhancer_image_caption_model = AutoModelForCausalLM.from_pretrained(
+            prompt_enhancer_image_caption_model_name_or_path, trust_remote_code=True
+        )
+        prompt_enhancer_image_caption_processor = AutoProcessor.from_pretrained(
+            prompt_enhancer_image_caption_model_name_or_path, trust_remote_code=True
+        )
+        prompt_enhancer_llm_model = AutoModelForCausalLM.from_pretrained(
+            prompt_enhancer_llm_model_name_or_path,
+            torch_dtype="bfloat16",
+        )
+        prompt_enhancer_llm_tokenizer = AutoTokenizer.from_pretrained(
+            prompt_enhancer_llm_model_name_or_path,
+        )
+    else:
+        prompt_enhancer_image_caption_model = None
+        prompt_enhancer_image_caption_processor = None
+        prompt_enhancer_llm_model = None
+        prompt_enhancer_llm_tokenizer = None
+
+    vae = vae.to(torch.bfloat16)
+    if precision == "bfloat16" and transformer.dtype != torch.bfloat16:
+        transformer = transformer.to(torch.bfloat16)
+    text_encoder = text_encoder.to(torch.bfloat16)
+
+    # Use submodels for the pipeline
+    submodel_dict = {
+        "transformer": transformer,
+        "patchifier": patchifier,
+        "text_encoder": text_encoder,
+        "tokenizer": tokenizer,
+        "scheduler": scheduler,
+        "vae": vae,
+        "prompt_enhancer_image_caption_model": prompt_enhancer_image_caption_model,
+        "prompt_enhancer_image_caption_processor": prompt_enhancer_image_caption_processor,
+        "prompt_enhancer_llm_model": prompt_enhancer_llm_model,
+        "prompt_enhancer_llm_tokenizer": prompt_enhancer_llm_tokenizer,
+        "allowed_inference_steps": allowed_inference_steps,
+    }
+
+    pipeline = LTXVideoPipeline(**submodel_dict)
+    pipeline = pipeline.to(device)
+    return pipeline
+
+
+def create_latent_upsampler(latent_upsampler_model_path: str, device: str):
+    latent_upsampler = LatentUpsampler.from_pretrained(latent_upsampler_model_path)
+    latent_upsampler.to(device)
+    latent_upsampler.eval()
+    return latent_upsampler
+
+
+def infer(
+    output_path: Optional[str],
+    seed: int,
+    pipeline_config: str,
+    image_cond_noise_scale: float,
+    height: Optional[int],
+    width: Optional[int],
+    num_frames: int,
+    frame_rate: int,
+    prompt: str,
+    negative_prompt: str,
+    offload_to_cpu: bool,
+    input_media_path: Optional[str] = None,
+    strength: Optional[float] = 1.0,
+    conditioning_media_paths: Optional[List[str]] = None,
+    conditioning_strengths: Optional[List[float]] = None,
+    conditioning_start_frames: Optional[List[int]] = None,
+    device: Optional[str] = None,
+    **kwargs,
+):
+    # check if pipeline_config is a file
+    if not os.path.isfile(pipeline_config):
+        raise ValueError(f"Pipeline config file {pipeline_config} does not exist")
+    with open(pipeline_config, "r") as f:
+        pipeline_config = yaml.safe_load(f)
+
+    models_dir = "MODEL_DIR"
+
+    #ltxv_model_name_or_path = pipeline_config["checkpoint_path"]
+    ltxv_model_name_or_path = "ltxv-13b-0.9.7-distilled-rc3.safetensors"
+    if not os.path.isfile(ltxv_model_name_or_path):
+        ltxv_model_path = hf_hub_download(
+            repo_id="LTX-Colab/LTX-Video-Preview",
+            #repo_id="Lightricks/LTX-Video",
+            filename=ltxv_model_name_or_path,
+            local_dir=models_dir,
+            repo_type="model",
+        )
+    else:
+        ltxv_model_path = ltxv_model_name_or_path
+
+    spatial_upscaler_model_name_or_path = pipeline_config.get(
+        "spatial_upscaler_model_path"
+    )
+    if spatial_upscaler_model_name_or_path and not os.path.isfile(
+        spatial_upscaler_model_name_or_path
+    ):
+        spatial_upscaler_model_path = hf_hub_download(
+            repo_id="Lightricks/LTX-Video",
+            filename=spatial_upscaler_model_name_or_path,
+            local_dir=models_dir,
+            repo_type="model",
+        )
+    else:
+        spatial_upscaler_model_path = spatial_upscaler_model_name_or_path
+
+    if kwargs.get("input_image_path", None):
+        logger.warning(
+            "Please use conditioning_media_paths instead of input_image_path."
+        )
+        assert not conditioning_media_paths and not conditioning_start_frames
+        conditioning_media_paths = [kwargs["input_image_path"]]
+        conditioning_start_frames = [0]
+
+    # Validate conditioning arguments
+    if conditioning_media_paths:
+        # Use default strengths of 1.0
+        if not conditioning_strengths:
+            conditioning_strengths = [1.0] * len(conditioning_media_paths)
+        if not conditioning_start_frames:
+            raise ValueError(
+                "If `conditioning_media_paths` is provided, "
+                "`conditioning_start_frames` must also be provided"
+            )
+        if len(conditioning_media_paths) != len(conditioning_strengths) or len(
+            conditioning_media_paths
+        ) != len(conditioning_start_frames):
+            raise ValueError(
+                "`conditioning_media_paths`, `conditioning_strengths`, "
+                "and `conditioning_start_frames` must have the same length"
+            )
+        if any(s < 0 or s > 1 for s in conditioning_strengths):
+            raise ValueError("All conditioning strengths must be between 0 and 1")
+        if any(f < 0 or f >= num_frames for f in conditioning_start_frames):
+            raise ValueError(
+                f"All conditioning start frames must be between 0 and {num_frames-1}"
+            )
+
+    seed_everething(seed)
+    if offload_to_cpu and not torch.cuda.is_available():
+        logger.warning(
+            "offload_to_cpu is set to True, but offloading will not occur since the model is already running on CPU."
+        )
+        offload_to_cpu = False
+    else:
+        offload_to_cpu = offload_to_cpu and get_total_gpu_memory() < 30
+
+    output_dir = (
+        Path(output_path)
+        if output_path
+        else Path(f"outputs/{datetime.today().strftime('%Y-%m-%d')}")
+    )
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    # Adjust dimensions to be divisible by 32 and num_frames to be (N * 8 + 1)
+    height_padded = ((height - 1) // 32 + 1) * 32
+    width_padded = ((width - 1) // 32 + 1) * 32
+    num_frames_padded = ((num_frames - 2) // 8 + 1) * 8 + 1
+
+    padding = calculate_padding(height, width, height_padded, width_padded)
+
+    logger.warning(
+        f"Padded dimensions: {height_padded}x{width_padded}x{num_frames_padded}"
+    )
+
+    prompt_enhancement_words_threshold = pipeline_config[
+        "prompt_enhancement_words_threshold"
+    ]
+
+    prompt_word_count = len(prompt.split())
+    enhance_prompt = (
+        prompt_enhancement_words_threshold > 0
+        and prompt_word_count < prompt_enhancement_words_threshold
+    )
+
+    if prompt_enhancement_words_threshold > 0 and not enhance_prompt:
+        logger.info(
+            f"Prompt has {prompt_word_count} words, which exceeds the threshold of {prompt_enhancement_words_threshold}. Prompt enhancement disabled."
+        )
+
+    precision = pipeline_config["precision"]
+    text_encoder_model_name_or_path = pipeline_config["text_encoder_model_name_or_path"]
+    sampler = pipeline_config["sampler"]
+    prompt_enhancer_image_caption_model_name_or_path = pipeline_config[
+        "prompt_enhancer_image_caption_model_name_or_path"
+    ]
+    prompt_enhancer_llm_model_name_or_path = pipeline_config[
+        "prompt_enhancer_llm_model_name_or_path"
+    ]
+
+    pipeline = create_ltx_video_pipeline(
+        ckpt_path=ltxv_model_path,
+        precision=precision,
+        text_encoder_model_name_or_path=text_encoder_model_name_or_path,
+        sampler=sampler,
+        device=kwargs.get("device", get_device()),
+        enhance_prompt=enhance_prompt,
+        prompt_enhancer_image_caption_model_name_or_path=prompt_enhancer_image_caption_model_name_or_path,
+        prompt_enhancer_llm_model_name_or_path=prompt_enhancer_llm_model_name_or_path,
+    )
+
+    if pipeline_config.get("pipeline_type", None) == "multi-scale":
+        if not spatial_upscaler_model_path:
+            raise ValueError(
+                "spatial upscaler model path is missing from pipeline config file and is required for multi-scale rendering"
+            )
+        latent_upsampler = create_latent_upsampler(
+            spatial_upscaler_model_path, pipeline.device
+        )
+        pipeline = LTXMultiScalePipeline(pipeline, latent_upsampler=latent_upsampler)
+
+    media_item = None
+    if input_media_path:
+        media_item = load_media_file(
+            media_path=input_media_path,
+            height=height,
+            width=width,
+            max_frames=num_frames_padded,
+            padding=padding,
+        )
+
+    conditioning_items = (
+        prepare_conditioning(
+            conditioning_media_paths=conditioning_media_paths,
+            conditioning_strengths=conditioning_strengths,
+            conditioning_start_frames=conditioning_start_frames,
+            height=height,
+            width=width,
+            num_frames=num_frames,
+            padding=padding,
+            pipeline=pipeline,
+        )
+        if conditioning_media_paths
+        else None
+    )
+
+    stg_mode = pipeline_config.get("stg_mode", "attention_values")
+    del pipeline_config["stg_mode"]
+    if stg_mode.lower() == "stg_av" or stg_mode.lower() == "attention_values":
+        skip_layer_strategy = SkipLayerStrategy.AttentionValues
+    elif stg_mode.lower() == "stg_as" or stg_mode.lower() == "attention_skip":
+        skip_layer_strategy = SkipLayerStrategy.AttentionSkip
+    elif stg_mode.lower() == "stg_r" or stg_mode.lower() == "residual":
+        skip_layer_strategy = SkipLayerStrategy.Residual
+    elif stg_mode.lower() == "stg_t" or stg_mode.lower() == "transformer_block":
+        skip_layer_strategy = SkipLayerStrategy.TransformerBlock
+    else:
+        raise ValueError(f"Invalid spatiotemporal guidance mode: {stg_mode}")
+
+    # Prepare input for the pipeline
+    sample = {
+        "prompt": prompt,
+        "prompt_attention_mask": None,
+        "negative_prompt": negative_prompt,
+        "negative_prompt_attention_mask": None,
+    }
+
+    device = device or get_device()
+    generator = torch.Generator(device=device).manual_seed(seed)
+
+    images = pipeline(
+        **pipeline_config,
+        skip_layer_strategy=skip_layer_strategy,
+        generator=generator,
+        output_type="pt",
+        callback_on_step_end=None,
+        height=height_padded,
+        width=width_padded,
+        num_frames=num_frames_padded,
+        frame_rate=frame_rate,
+        **sample,
+        media_items=media_item,
+        strength=strength,
+        conditioning_items=conditioning_items,
+        is_video=True,
+        vae_per_channel_normalize=True,
+        image_cond_noise_scale=image_cond_noise_scale,
+        mixed_precision=(precision == "mixed_precision"),
+        offload_to_cpu=offload_to_cpu,
+        device=device,
+        enhance_prompt=enhance_prompt,
+    ).images
+
+    # Crop the padded images to the desired resolution and number of frames
+    (pad_left, pad_right, pad_top, pad_bottom) = padding
+    pad_bottom = -pad_bottom
+    pad_right = -pad_right
+    if pad_bottom == 0:
+        pad_bottom = images.shape[3]
+    if pad_right == 0:
+        pad_right = images.shape[4]
+    images = images[:, :, :num_frames, pad_top:pad_bottom, pad_left:pad_right]
+
+    for i in range(images.shape[0]):
+        # Gathering from B, C, F, H, W to C, F, H, W and then permuting to F, H, W, C
+        video_np = images[i].permute(1, 2, 3, 0).cpu().float().numpy()
+        # Unnormalizing images to [0, 255] range
+        video_np = (video_np * 255).astype(np.uint8)
+        fps = frame_rate
+        height, width = video_np.shape[1:3]
+        # In case a single image is generated
+        if video_np.shape[0] == 1:
+            output_filename = get_unique_filename(
+                f"image_output_{i}",
+                ".png",
+                prompt=prompt,
+                seed=seed,
+                resolution=(height, width, num_frames),
+                dir=output_dir,
+            )
+            imageio.imwrite(output_filename, video_np[0])
+        else:
+            output_filename = get_unique_filename(
+                f"video_output_{i}",
+                ".mp4",
+                prompt=prompt,
+                seed=seed,
+                resolution=(height, width, num_frames),
+                dir=output_dir,
+            )
+
+            # Write video
+            with imageio.get_writer(output_filename, fps=fps) as video:
+                for frame in video_np:
+                    video.append_data(frame)
+
+        logger.warning(f"Output saved to {output_filename}")
+
+
+def prepare_conditioning(
+    conditioning_media_paths: List[str],
+    conditioning_strengths: List[float],
+    conditioning_start_frames: List[int],
+    height: int,
+    width: int,
+    num_frames: int,
+    padding: tuple[int, int, int, int],
+    pipeline: LTXVideoPipeline,
+) -> Optional[List[ConditioningItem]]:
+    """Prepare conditioning items based on input media paths and their parameters.
+
+    Args:
+        conditioning_media_paths: List of paths to conditioning media (images or videos)
+        conditioning_strengths: List of conditioning strengths for each media item
+        conditioning_start_frames: List of frame indices where each item should be applied
+        height: Height of the output frames
+        width: Width of the output frames
+        num_frames: Number of frames in the output video
+        padding: Padding to apply to the frames
+        pipeline: LTXVideoPipeline object used for condition video trimming
+
+    Returns:
+        A list of ConditioningItem objects.
+    """
+    conditioning_items = []
+    for path, strength, start_frame in zip(
+        conditioning_media_paths, conditioning_strengths, conditioning_start_frames
+    ):
+        num_input_frames = orig_num_input_frames = get_media_num_frames(path)
+        if hasattr(pipeline, "trim_conditioning_sequence") and callable(
+            getattr(pipeline, "trim_conditioning_sequence")
+        ):
+            num_input_frames = pipeline.trim_conditioning_sequence(
+                start_frame, orig_num_input_frames, num_frames
+            )
+        if num_input_frames < orig_num_input_frames:
+            logger.warning(
+                f"Trimming conditioning video {path} from {orig_num_input_frames} to {num_input_frames} frames."
+            )
+
+        media_tensor = load_media_file(
+            media_path=path,
+            height=height,
+            width=width,
+            max_frames=num_input_frames,
+            padding=padding,
+            just_crop=True,
+        )
+        conditioning_items.append(ConditioningItem(media_tensor, start_frame, strength))
+    return conditioning_items
+
+
+def get_media_num_frames(media_path: str) -> int:
+    is_video = any(
+        media_path.lower().endswith(ext) for ext in [".mp4", ".avi", ".mov", ".mkv"]
+    )
+    num_frames = 1
+    if is_video:
+        reader = imageio.get_reader(media_path)
+        num_frames = reader.count_frames()
+        reader.close()
+    return num_frames
+
+
+def load_media_file(
+    media_path: str,
+    height: int,
+    width: int,
+    max_frames: int,
+    padding: tuple[int, int, int, int],
+    just_crop: bool = False,
+) -> torch.Tensor:
+    is_video = any(
+        media_path.lower().endswith(ext) for ext in [".mp4", ".avi", ".mov", ".mkv"]
+    )
+    if is_video:
+        reader = imageio.get_reader(media_path)
+        num_input_frames = min(reader.count_frames(), max_frames)
+
+        # Read and preprocess the relevant frames from the video file.
+        frames = []
+        for i in range(num_input_frames):
+            frame = Image.fromarray(reader.get_data(i))
+            frame_tensor = load_image_to_tensor_with_resize_and_crop(
+                frame, height, width, just_crop=just_crop
+            )
+            frame_tensor = torch.nn.functional.pad(frame_tensor, padding)
+            frames.append(frame_tensor)
+        reader.close()
+
+        # Stack frames along the temporal dimension
+        media_tensor = torch.cat(frames, dim=2)
+    else:  # Input image
+        media_tensor = load_image_to_tensor_with_resize_and_crop(
+            media_path, height, width, just_crop=just_crop
+        )
+        media_tensor = torch.nn.functional.pad(media_tensor, padding)
+    return media_tensor
+
+
+if __name__ == "__main__":
+    main()

ltx_video/models/autoencoders/causal_conv3d.py

@@ -0,0 +1,63 @@
+from typing import Tuple, Union
+
+import torch
+import torch.nn as nn
+
+
+class CausalConv3d(nn.Module):
+    def __init__(
+        self,
+        in_channels,
+        out_channels,
+        kernel_size: int = 3,
+        stride: Union[int, Tuple[int]] = 1,
+        dilation: int = 1,
+        groups: int = 1,
+        spatial_padding_mode: str = "zeros",
+        **kwargs,
+    ):
+        super().__init__()
+
+        self.in_channels = in_channels
+        self.out_channels = out_channels
+
+        kernel_size = (kernel_size, kernel_size, kernel_size)
+        self.time_kernel_size = kernel_size[0]
+
+        dilation = (dilation, 1, 1)
+
+        height_pad = kernel_size[1] // 2
+        width_pad = kernel_size[2] // 2
+        padding = (0, height_pad, width_pad)
+
+        self.conv = nn.Conv3d(
+            in_channels,
+            out_channels,
+            kernel_size,
+            stride=stride,
+            dilation=dilation,
+            padding=padding,
+            padding_mode=spatial_padding_mode,
+            groups=groups,
+        )
+
+    def forward(self, x, causal: bool = True):
+        if causal:
+            first_frame_pad = x[:, :, :1, :, :].repeat(
+                (1, 1, self.time_kernel_size - 1, 1, 1)
+            )
+            x = torch.concatenate((first_frame_pad, x), dim=2)
+        else:
+            first_frame_pad = x[:, :, :1, :, :].repeat(
+                (1, 1, (self.time_kernel_size - 1) // 2, 1, 1)
+            )
+            last_frame_pad = x[:, :, -1:, :, :].repeat(
+                (1, 1, (self.time_kernel_size - 1) // 2, 1, 1)
+            )
+            x = torch.concatenate((first_frame_pad, x, last_frame_pad), dim=2)
+        x = self.conv(x)
+        return x
+
+    @property
+    def weight(self):
+        return self.conv.weight

ltx_video/models/autoencoders/causal_video_autoencoder.py

@@ -0,0 +1,1403 @@
+import json
+import os
+from functools import partial
+from types import SimpleNamespace
+from typing import Any, Mapping, Optional, Tuple, Union, List
+from pathlib import Path
+
+import torch
+import numpy as np
+from einops import rearrange
+from torch import nn
+from diffusers.utils import logging
+import torch.nn.functional as F
+from diffusers.models.embeddings import PixArtAlphaCombinedTimestepSizeEmbeddings
+from safetensors import safe_open
+
+
+from ltx_video.models.autoencoders.conv_nd_factory import make_conv_nd, make_linear_nd
+from ltx_video.models.autoencoders.pixel_norm import PixelNorm
+from ltx_video.models.autoencoders.pixel_shuffle import PixelShuffleND
+from ltx_video.models.autoencoders.vae import AutoencoderKLWrapper
+from ltx_video.models.transformers.attention import Attention
+from ltx_video.utils.diffusers_config_mapping import (
+    diffusers_and_ours_config_mapping,
+    make_hashable_key,
+    VAE_KEYS_RENAME_DICT,
+)
+
+PER_CHANNEL_STATISTICS_PREFIX = "per_channel_statistics."
+logger = logging.get_logger(__name__)  # pylint: disable=invalid-name
+
+
+class CausalVideoAutoencoder(AutoencoderKLWrapper):
+    @classmethod
+    def from_pretrained(
+        cls,
+        pretrained_model_name_or_path: Optional[Union[str, os.PathLike]],
+        *args,
+        **kwargs,
+    ):
+        pretrained_model_name_or_path = Path(pretrained_model_name_or_path)
+        if (
+            pretrained_model_name_or_path.is_dir()
+            and (pretrained_model_name_or_path / "autoencoder.pth").exists()
+        ):
+            config_local_path = pretrained_model_name_or_path / "config.json"
+            config = cls.load_config(config_local_path, **kwargs)
+
+            model_local_path = pretrained_model_name_or_path / "autoencoder.pth"
+            state_dict = torch.load(model_local_path, map_location=torch.device("cpu"))
+
+            statistics_local_path = (
+                pretrained_model_name_or_path / "per_channel_statistics.json"
+            )
+            if statistics_local_path.exists():
+                with open(statistics_local_path, "r") as file:
+                    data = json.load(file)
+                transposed_data = list(zip(*data["data"]))
+                data_dict = {
+                    col: torch.tensor(vals)
+                    for col, vals in zip(data["columns"], transposed_data)
+                }
+                std_of_means = data_dict["std-of-means"]
+                mean_of_means = data_dict.get(
+                    "mean-of-means", torch.zeros_like(data_dict["std-of-means"])
+                )
+                state_dict[f"{PER_CHANNEL_STATISTICS_PREFIX}std-of-means"] = (
+                    std_of_means
+                )
+                state_dict[f"{PER_CHANNEL_STATISTICS_PREFIX}mean-of-means"] = (
+                    mean_of_means
+                )
+
+        elif pretrained_model_name_or_path.is_dir():
+            config_path = pretrained_model_name_or_path / "vae" / "config.json"
+            with open(config_path, "r") as f:
+                config = make_hashable_key(json.load(f))
+
+            assert config in diffusers_and_ours_config_mapping, (
+                "Provided diffusers checkpoint config for VAE is not suppported. "
+                "We only support diffusers configs found in Lightricks/LTX-Video."
+            )
+
+            config = diffusers_and_ours_config_mapping[config]
+
+            state_dict_path = (
+                pretrained_model_name_or_path
+                / "vae"
+                / "diffusion_pytorch_model.safetensors"
+            )
+
+            state_dict = {}
+            with safe_open(state_dict_path, framework="pt", device="cpu") as f:
+                for k in f.keys():
+                    state_dict[k] = f.get_tensor(k)
+            for key in list(state_dict.keys()):
+                new_key = key
+                for replace_key, rename_key in VAE_KEYS_RENAME_DICT.items():
+                    new_key = new_key.replace(replace_key, rename_key)
+
+                state_dict[new_key] = state_dict.pop(key)
+
+        elif pretrained_model_name_or_path.is_file() and str(
+            pretrained_model_name_or_path
+        ).endswith(".safetensors"):
+            state_dict = {}
+            with safe_open(
+                pretrained_model_name_or_path, framework="pt", device="cpu"
+            ) as f:
+                metadata = f.metadata()
+                for k in f.keys():
+                    state_dict[k] = f.get_tensor(k)
+            configs = json.loads(metadata["config"])
+            config = configs["vae"]
+
+        video_vae = cls.from_config(config)
+        if "torch_dtype" in kwargs:
+            video_vae.to(kwargs["torch_dtype"])
+        video_vae.load_state_dict(state_dict)
+        return video_vae
+
+    @staticmethod
+    def from_config(config):
+        assert (
+            config["_class_name"] == "CausalVideoAutoencoder"
+        ), "config must have _class_name=CausalVideoAutoencoder"
+        if isinstance(config["dims"], list):
+            config["dims"] = tuple(config["dims"])
+
+        assert config["dims"] in [2, 3, (2, 1)], "dims must be 2, 3 or (2, 1)"
+
+        double_z = config.get("double_z", True)
+        latent_log_var = config.get(
+            "latent_log_var", "per_channel" if double_z else "none"
+        )
+        use_quant_conv = config.get("use_quant_conv", True)
+        normalize_latent_channels = config.get("normalize_latent_channels", False)
+
+        if use_quant_conv and latent_log_var in ["uniform", "constant"]:
+            raise ValueError(
+                f"latent_log_var={latent_log_var} requires use_quant_conv=False"
+            )
+
+        encoder = Encoder(
+            dims=config["dims"],
+            in_channels=config.get("in_channels", 3),
+            out_channels=config["latent_channels"],
+            blocks=config.get("encoder_blocks", config.get("blocks")),
+            patch_size=config.get("patch_size", 1),
+            latent_log_var=latent_log_var,
+            norm_layer=config.get("norm_layer", "group_norm"),
+            base_channels=config.get("encoder_base_channels", 128),
+            spatial_padding_mode=config.get("spatial_padding_mode", "zeros"),
+        )
+
+        decoder = Decoder(
+            dims=config["dims"],
+            in_channels=config["latent_channels"],
+            out_channels=config.get("out_channels", 3),
+            blocks=config.get("decoder_blocks", config.get("blocks")),
+            patch_size=config.get("patch_size", 1),
+            norm_layer=config.get("norm_layer", "group_norm"),
+            causal=config.get("causal_decoder", False),
+            timestep_conditioning=config.get("timestep_conditioning", False),
+            base_channels=config.get("decoder_base_channels", 128),
+            spatial_padding_mode=config.get("spatial_padding_mode", "zeros"),
+        )
+
+        dims = config["dims"]
+        return CausalVideoAutoencoder(
+            encoder=encoder,
+            decoder=decoder,
+            latent_channels=config["latent_channels"],
+            dims=dims,
+            use_quant_conv=use_quant_conv,
+            normalize_latent_channels=normalize_latent_channels,
+        )
+
+    @property
+    def config(self):
+        return SimpleNamespace(
+            _class_name="CausalVideoAutoencoder",
+            dims=self.dims,
+            in_channels=self.encoder.conv_in.in_channels // self.encoder.patch_size**2,
+            out_channels=self.decoder.conv_out.out_channels
+            // self.decoder.patch_size**2,
+            latent_channels=self.decoder.conv_in.in_channels,
+            encoder_blocks=self.encoder.blocks_desc,
+            decoder_blocks=self.decoder.blocks_desc,
+            scaling_factor=1.0,
+            norm_layer=self.encoder.norm_layer,
+            patch_size=self.encoder.patch_size,
+            latent_log_var=self.encoder.latent_log_var,
+            use_quant_conv=self.use_quant_conv,
+            causal_decoder=self.decoder.causal,
+            timestep_conditioning=self.decoder.timestep_conditioning,
+            normalize_latent_channels=self.normalize_latent_channels,
+        )
+
+    @property
+    def is_video_supported(self):
+        """
+        Check if the model supports video inputs of shape (B, C, F, H, W). Otherwise, the model only supports 2D images.
+        """
+        return self.dims != 2
+
+    @property
+    def spatial_downscale_factor(self):
+        return (
+            2
+            ** len(
+                [
+                    block
+                    for block in self.encoder.blocks_desc
+                    if block[0]
+                    in [
+                        "compress_space",
+                        "compress_all",
+                        "compress_all_res",
+                        "compress_space_res",
+                    ]
+                ]
+            )
+            * self.encoder.patch_size
+        )
+
+    @property
+    def temporal_downscale_factor(self):
+        return 2 ** len(
+            [
+                block
+                for block in self.encoder.blocks_desc
+                if block[0]
+                in [
+                    "compress_time",
+                    "compress_all",
+                    "compress_all_res",
+                    "compress_space_res",
+                ]
+            ]
+        )
+
+    def to_json_string(self) -> str:
+        import json
+
+        return json.dumps(self.config.__dict__)
+
+    def load_state_dict(self, state_dict: Mapping[str, Any], strict: bool = True):
+        if any([key.startswith("vae.") for key in state_dict.keys()]):
+            state_dict = {
+                key.replace("vae.", ""): value
+                for key, value in state_dict.items()
+                if key.startswith("vae.")
+            }
+        ckpt_state_dict = {
+            key: value
+            for key, value in state_dict.items()
+            if not key.startswith(PER_CHANNEL_STATISTICS_PREFIX)
+        }
+
+        model_keys = set(name for name, _ in self.named_modules())
+
+        key_mapping = {
+            ".resnets.": ".res_blocks.",
+            "downsamplers.0": "downsample",
+            "upsamplers.0": "upsample",
+        }
+        converted_state_dict = {}
+        for key, value in ckpt_state_dict.items():
+            for k, v in key_mapping.items():
+                key = key.replace(k, v)
+
+            key_prefix = ".".join(key.split(".")[:-1])
+            if "norm" in key and key_prefix not in model_keys:
+                logger.info(
+                    f"Removing key {key} from state_dict as it is not present in the model"
+                )
+                continue
+
+            converted_state_dict[key] = value
+
+        super().load_state_dict(converted_state_dict, strict=strict)
+
+        data_dict = {
+            key.removeprefix(PER_CHANNEL_STATISTICS_PREFIX): value
+            for key, value in state_dict.items()
+            if key.startswith(PER_CHANNEL_STATISTICS_PREFIX)
+        }
+        if len(data_dict) > 0:
+            self.register_buffer("std_of_means", data_dict["std-of-means"])
+            self.register_buffer(
+                "mean_of_means",
+                data_dict.get(
+                    "mean-of-means", torch.zeros_like(data_dict["std-of-means"])
+                ),
+            )
+
+    def last_layer(self):
+        if hasattr(self.decoder, "conv_out"):
+            if isinstance(self.decoder.conv_out, nn.Sequential):
+                last_layer = self.decoder.conv_out[-1]
+            else:
+                last_layer = self.decoder.conv_out
+        else:
+            last_layer = self.decoder.layers[-1]
+        return last_layer
+
+    def set_use_tpu_flash_attention(self):
+        for block in self.decoder.up_blocks:
+            if isinstance(block, UNetMidBlock3D) and block.attention_blocks:
+                for attention_block in block.attention_blocks:
+                    attention_block.set_use_tpu_flash_attention()
+
+
+class Encoder(nn.Module):
+    r"""
+    The `Encoder` layer of a variational autoencoder that encodes its input into a latent representation.
+
+    Args:
+        dims (`int` or `Tuple[int, int]`, *optional*, defaults to 3):
+            The number of dimensions to use in convolutions.
+        in_channels (`int`, *optional*, defaults to 3):
+            The number of input channels.
+        out_channels (`int`, *optional*, defaults to 3):
+            The number of output channels.
+        blocks (`List[Tuple[str, int]]`, *optional*, defaults to `[("res_x", 1)]`):
+            The blocks to use. Each block is a tuple of the block name and the number of layers.
+        base_channels (`int`, *optional*, defaults to 128):
+            The number of output channels for the first convolutional layer.
+        norm_num_groups (`int`, *optional*, defaults to 32):
+            The number of groups for normalization.
+        patch_size (`int`, *optional*, defaults to 1):
+            The patch size to use. Should be a power of 2.
+        norm_layer (`str`, *optional*, defaults to `group_norm`):
+            The normalization layer to use. Can be either `group_norm` or `pixel_norm`.
+        latent_log_var (`str`, *optional*, defaults to `per_channel`):
+            The number of channels for the log variance. Can be either `per_channel`, `uniform`, `constant` or `none`.
+    """
+
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]] = 3,
+        in_channels: int = 3,
+        out_channels: int = 3,
+        blocks: List[Tuple[str, int | dict]] = [("res_x", 1)],
+        base_channels: int = 128,
+        norm_num_groups: int = 32,
+        patch_size: Union[int, Tuple[int]] = 1,
+        norm_layer: str = "group_norm",  # group_norm, pixel_norm
+        latent_log_var: str = "per_channel",
+        spatial_padding_mode: str = "zeros",
+    ):
+        super().__init__()
+        self.patch_size = patch_size
+        self.norm_layer = norm_layer
+        self.latent_channels = out_channels
+        self.latent_log_var = latent_log_var
+        self.blocks_desc = blocks
+
+        in_channels = in_channels * patch_size**2
+        output_channel = base_channels
+
+        self.conv_in = make_conv_nd(
+            dims=dims,
+            in_channels=in_channels,
+            out_channels=output_channel,
+            kernel_size=3,
+            stride=1,
+            padding=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+        self.down_blocks = nn.ModuleList([])
+
+        for block_name, block_params in blocks:
+            input_channel = output_channel
+            if isinstance(block_params, int):
+                block_params = {"num_layers": block_params}
+
+            if block_name == "res_x":
+                block = UNetMidBlock3D(
+                    dims=dims,
+                    in_channels=input_channel,
+                    num_layers=block_params["num_layers"],
+                    resnet_eps=1e-6,
+                    resnet_groups=norm_num_groups,
+                    norm_layer=norm_layer,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "res_x_y":
+                output_channel = block_params.get("multiplier", 2) * output_channel
+                block = ResnetBlock3D(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    eps=1e-6,
+                    groups=norm_num_groups,
+                    norm_layer=norm_layer,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_time":
+                block = make_conv_nd(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    kernel_size=3,
+                    stride=(2, 1, 1),
+                    causal=True,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_space":
+                block = make_conv_nd(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    kernel_size=3,
+                    stride=(1, 2, 2),
+                    causal=True,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_all":
+                block = make_conv_nd(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    kernel_size=3,
+                    stride=(2, 2, 2),
+                    causal=True,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_all_x_y":
+                output_channel = block_params.get("multiplier", 2) * output_channel
+                block = make_conv_nd(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    kernel_size=3,
+                    stride=(2, 2, 2),
+                    causal=True,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_all_res":
+                output_channel = block_params.get("multiplier", 2) * output_channel
+                block = SpaceToDepthDownsample(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    stride=(2, 2, 2),
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_space_res":
+                output_channel = block_params.get("multiplier", 2) * output_channel
+                block = SpaceToDepthDownsample(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    stride=(1, 2, 2),
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_time_res":
+                output_channel = block_params.get("multiplier", 2) * output_channel
+                block = SpaceToDepthDownsample(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    stride=(2, 1, 1),
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            else:
+                raise ValueError(f"unknown block: {block_name}")
+
+            self.down_blocks.append(block)
+
+        # out
+        if norm_layer == "group_norm":
+            self.conv_norm_out = nn.GroupNorm(
+                num_channels=output_channel, num_groups=norm_num_groups, eps=1e-6
+            )
+        elif norm_layer == "pixel_norm":
+            self.conv_norm_out = PixelNorm()
+        elif norm_layer == "layer_norm":
+            self.conv_norm_out = LayerNorm(output_channel, eps=1e-6)
+
+        self.conv_act = nn.SiLU()
+
+        conv_out_channels = out_channels
+        if latent_log_var == "per_channel":
+            conv_out_channels *= 2
+        elif latent_log_var == "uniform":
+            conv_out_channels += 1
+        elif latent_log_var == "constant":
+            conv_out_channels += 1
+        elif latent_log_var != "none":
+            raise ValueError(f"Invalid latent_log_var: {latent_log_var}")
+        self.conv_out = make_conv_nd(
+            dims,
+            output_channel,
+            conv_out_channels,
+            3,
+            padding=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+        self.gradient_checkpointing = False
+
+    def forward(self, sample: torch.FloatTensor) -> torch.FloatTensor:
+        r"""The forward method of the `Encoder` class."""
+
+        sample = patchify(sample, patch_size_hw=self.patch_size, patch_size_t=1)
+        sample = self.conv_in(sample)
+
+        checkpoint_fn = (
+            partial(torch.utils.checkpoint.checkpoint, use_reentrant=False)
+            if self.gradient_checkpointing and self.training
+            else lambda x: x
+        )
+
+        for down_block in self.down_blocks:
+            sample = checkpoint_fn(down_block)(sample)
+
+        sample = self.conv_norm_out(sample)
+        sample = self.conv_act(sample)
+        sample = self.conv_out(sample)
+
+        if self.latent_log_var == "uniform":
+            last_channel = sample[:, -1:, ...]
+            num_dims = sample.dim()
+
+            if num_dims == 4:
+                # For shape (B, C, H, W)
+                repeated_last_channel = last_channel.repeat(
+                    1, sample.shape[1] - 2, 1, 1
+                )
+                sample = torch.cat([sample, repeated_last_channel], dim=1)
+            elif num_dims == 5:
+                # For shape (B, C, F, H, W)
+                repeated_last_channel = last_channel.repeat(
+                    1, sample.shape[1] - 2, 1, 1, 1
+                )
+                sample = torch.cat([sample, repeated_last_channel], dim=1)
+            else:
+                raise ValueError(f"Invalid input shape: {sample.shape}")
+        elif self.latent_log_var == "constant":
+            sample = sample[:, :-1, ...]
+            approx_ln_0 = (
+                -30
+            )  # this is the minimal clamp value in DiagonalGaussianDistribution objects
+            sample = torch.cat(
+                [sample, torch.ones_like(sample, device=sample.device) * approx_ln_0],
+                dim=1,
+            )
+
+        return sample
+
+
+class Decoder(nn.Module):
+    r"""
+    The `Decoder` layer of a variational autoencoder that decodes its latent representation into an output sample.
+
+    Args:
+        dims (`int` or `Tuple[int, int]`, *optional*, defaults to 3):
+            The number of dimensions to use in convolutions.
+        in_channels (`int`, *optional*, defaults to 3):
+            The number of input channels.
+        out_channels (`int`, *optional*, defaults to 3):
+            The number of output channels.
+        blocks (`List[Tuple[str, int]]`, *optional*, defaults to `[("res_x", 1)]`):
+            The blocks to use. Each block is a tuple of the block name and the number of layers.
+        base_channels (`int`, *optional*, defaults to 128):
+            The number of output channels for the first convolutional layer.
+        norm_num_groups (`int`, *optional*, defaults to 32):
+            The number of groups for normalization.
+        patch_size (`int`, *optional*, defaults to 1):
+            The patch size to use. Should be a power of 2.
+        norm_layer (`str`, *optional*, defaults to `group_norm`):
+            The normalization layer to use. Can be either `group_norm` or `pixel_norm`.
+        causal (`bool`, *optional*, defaults to `True`):
+            Whether to use causal convolutions or not.
+    """
+
+    def __init__(
+        self,
+        dims,
+        in_channels: int = 3,
+        out_channels: int = 3,
+        blocks: List[Tuple[str, int | dict]] = [("res_x", 1)],
+        base_channels: int = 128,
+        layers_per_block: int = 2,
+        norm_num_groups: int = 32,
+        patch_size: int = 1,
+        norm_layer: str = "group_norm",
+        causal: bool = True,
+        timestep_conditioning: bool = False,
+        spatial_padding_mode: str = "zeros",
+    ):
+        super().__init__()
+        self.patch_size = patch_size
+        self.layers_per_block = layers_per_block
+        out_channels = out_channels * patch_size**2
+        self.causal = causal
+        self.blocks_desc = blocks
+
+        # Compute output channel to be product of all channel-multiplier blocks
+        output_channel = base_channels
+        for block_name, block_params in list(reversed(blocks)):
+            block_params = block_params if isinstance(block_params, dict) else {}
+            if block_name == "res_x_y":
+                output_channel = output_channel * block_params.get("multiplier", 2)
+            if block_name == "compress_all":
+                output_channel = output_channel * block_params.get("multiplier", 1)
+
+        self.conv_in = make_conv_nd(
+            dims,
+            in_channels,
+            output_channel,
+            kernel_size=3,
+            stride=1,
+            padding=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+        self.up_blocks = nn.ModuleList([])
+
+        for block_name, block_params in list(reversed(blocks)):
+            input_channel = output_channel
+            if isinstance(block_params, int):
+                block_params = {"num_layers": block_params}
+
+            if block_name == "res_x":
+                block = UNetMidBlock3D(
+                    dims=dims,
+                    in_channels=input_channel,
+                    num_layers=block_params["num_layers"],
+                    resnet_eps=1e-6,
+                    resnet_groups=norm_num_groups,
+                    norm_layer=norm_layer,
+                    inject_noise=block_params.get("inject_noise", False),
+                    timestep_conditioning=timestep_conditioning,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "attn_res_x":
+                block = UNetMidBlock3D(
+                    dims=dims,
+                    in_channels=input_channel,
+                    num_layers=block_params["num_layers"],
+                    resnet_groups=norm_num_groups,
+                    norm_layer=norm_layer,
+                    inject_noise=block_params.get("inject_noise", False),
+                    timestep_conditioning=timestep_conditioning,
+                    attention_head_dim=block_params["attention_head_dim"],
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "res_x_y":
+                output_channel = output_channel // block_params.get("multiplier", 2)
+                block = ResnetBlock3D(
+                    dims=dims,
+                    in_channels=input_channel,
+                    out_channels=output_channel,
+                    eps=1e-6,
+                    groups=norm_num_groups,
+                    norm_layer=norm_layer,
+                    inject_noise=block_params.get("inject_noise", False),
+                    timestep_conditioning=False,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_time":
+                block = DepthToSpaceUpsample(
+                    dims=dims,
+                    in_channels=input_channel,
+                    stride=(2, 1, 1),
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_space":
+                block = DepthToSpaceUpsample(
+                    dims=dims,
+                    in_channels=input_channel,
+                    stride=(1, 2, 2),
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            elif block_name == "compress_all":
+                output_channel = output_channel // block_params.get("multiplier", 1)
+                block = DepthToSpaceUpsample(
+                    dims=dims,
+                    in_channels=input_channel,
+                    stride=(2, 2, 2),
+                    residual=block_params.get("residual", False),
+                    out_channels_reduction_factor=block_params.get("multiplier", 1),
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+            else:
+                raise ValueError(f"unknown layer: {block_name}")
+
+            self.up_blocks.append(block)
+
+        if norm_layer == "group_norm":
+            self.conv_norm_out = nn.GroupNorm(
+                num_channels=output_channel, num_groups=norm_num_groups, eps=1e-6
+            )
+        elif norm_layer == "pixel_norm":
+            self.conv_norm_out = PixelNorm()
+        elif norm_layer == "layer_norm":
+            self.conv_norm_out = LayerNorm(output_channel, eps=1e-6)
+
+        self.conv_act = nn.SiLU()
+        self.conv_out = make_conv_nd(
+            dims,
+            output_channel,
+            out_channels,
+            3,
+            padding=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+        self.gradient_checkpointing = False
+
+        self.timestep_conditioning = timestep_conditioning
+
+        if timestep_conditioning:
+            self.timestep_scale_multiplier = nn.Parameter(
+                torch.tensor(1000.0, dtype=torch.float32)
+            )
+            self.last_time_embedder = PixArtAlphaCombinedTimestepSizeEmbeddings(
+                output_channel * 2, 0
+            )
+            self.last_scale_shift_table = nn.Parameter(
+                torch.randn(2, output_channel) / output_channel**0.5
+            )
+
+    def forward(
+        self,
+        sample: torch.FloatTensor,
+        target_shape,
+        timestep: Optional[torch.Tensor] = None,
+    ) -> torch.FloatTensor:
+        r"""The forward method of the `Decoder` class."""
+        assert target_shape is not None, "target_shape must be provided"
+        batch_size = sample.shape[0]
+
+        sample = self.conv_in(sample, causal=self.causal)
+
+        upscale_dtype = next(iter(self.up_blocks.parameters())).dtype
+
+        checkpoint_fn = (
+            partial(torch.utils.checkpoint.checkpoint, use_reentrant=False)
+            if self.gradient_checkpointing and self.training
+            else lambda x: x
+        )
+
+        sample = sample.to(upscale_dtype)
+
+        if self.timestep_conditioning:
+            assert (
+                timestep is not None
+            ), "should pass timestep with timestep_conditioning=True"
+            scaled_timestep = timestep * self.timestep_scale_multiplier
+
+        for up_block in self.up_blocks:
+            if self.timestep_conditioning and isinstance(up_block, UNetMidBlock3D):
+                sample = checkpoint_fn(up_block)(
+                    sample, causal=self.causal, timestep=scaled_timestep
+                )
+            else:
+                sample = checkpoint_fn(up_block)(sample, causal=self.causal)
+
+        sample = self.conv_norm_out(sample)
+
+        if self.timestep_conditioning:
+            embedded_timestep = self.last_time_embedder(
+                timestep=scaled_timestep.flatten(),
+                resolution=None,
+                aspect_ratio=None,
+                batch_size=sample.shape[0],
+                hidden_dtype=sample.dtype,
+            )
+            embedded_timestep = embedded_timestep.view(
+                batch_size, embedded_timestep.shape[-1], 1, 1, 1
+            )
+            ada_values = self.last_scale_shift_table[
+                None, ..., None, None, None
+            ] + embedded_timestep.reshape(
+                batch_size,
+                2,
+                -1,
+                embedded_timestep.shape[-3],
+                embedded_timestep.shape[-2],
+                embedded_timestep.shape[-1],
+            )
+            shift, scale = ada_values.unbind(dim=1)
+            sample = sample * (1 + scale) + shift
+
+        sample = self.conv_act(sample)
+        sample = self.conv_out(sample, causal=self.causal)
+
+        sample = unpatchify(sample, patch_size_hw=self.patch_size, patch_size_t=1)
+
+        return sample
+
+
+class UNetMidBlock3D(nn.Module):
+    """
+    A 3D UNet mid-block [`UNetMidBlock3D`] with multiple residual blocks.
+
+    Args:
+        in_channels (`int`): The number of input channels.
+        dropout (`float`, *optional*, defaults to 0.0): The dropout rate.
+        num_layers (`int`, *optional*, defaults to 1): The number of residual blocks.
+        resnet_eps (`float`, *optional*, 1e-6 ): The epsilon value for the resnet blocks.
+        resnet_groups (`int`, *optional*, defaults to 32):
+            The number of groups to use in the group normalization layers of the resnet blocks.
+        norm_layer (`str`, *optional*, defaults to `group_norm`):
+            The normalization layer to use. Can be either `group_norm` or `pixel_norm`.
+        inject_noise (`bool`, *optional*, defaults to `False`):
+            Whether to inject noise into the hidden states.
+        timestep_conditioning (`bool`, *optional*, defaults to `False`):
+            Whether to condition the hidden states on the timestep.
+        attention_head_dim (`int`, *optional*, defaults to -1):
+            The dimension of the attention head. If -1, no attention is used.
+
+    Returns:
+        `torch.FloatTensor`: The output of the last residual block, which is a tensor of shape `(batch_size,
+        in_channels, height, width)`.
+
+    """
+
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]],
+        in_channels: int,
+        dropout: float = 0.0,
+        num_layers: int = 1,
+        resnet_eps: float = 1e-6,
+        resnet_groups: int = 32,
+        norm_layer: str = "group_norm",
+        inject_noise: bool = False,
+        timestep_conditioning: bool = False,
+        attention_head_dim: int = -1,
+        spatial_padding_mode: str = "zeros",
+    ):
+        super().__init__()
+        resnet_groups = (
+            resnet_groups if resnet_groups is not None else min(in_channels // 4, 32)
+        )
+        self.timestep_conditioning = timestep_conditioning
+
+        if timestep_conditioning:
+            self.time_embedder = PixArtAlphaCombinedTimestepSizeEmbeddings(
+                in_channels * 4, 0
+            )
+
+        self.res_blocks = nn.ModuleList(
+            [
+                ResnetBlock3D(
+                    dims=dims,
+                    in_channels=in_channels,
+                    out_channels=in_channels,
+                    eps=resnet_eps,
+                    groups=resnet_groups,
+                    dropout=dropout,
+                    norm_layer=norm_layer,
+                    inject_noise=inject_noise,
+                    timestep_conditioning=timestep_conditioning,
+                    spatial_padding_mode=spatial_padding_mode,
+                )
+                for _ in range(num_layers)
+            ]
+        )
+
+        self.attention_blocks = None
+
+        if attention_head_dim > 0:
+            if attention_head_dim > in_channels:
+                raise ValueError(
+                    "attention_head_dim must be less than or equal to in_channels"
+                )
+
+            self.attention_blocks = nn.ModuleList(
+                [
+                    Attention(
+                        query_dim=in_channels,
+                        heads=in_channels // attention_head_dim,
+                        dim_head=attention_head_dim,
+                        bias=True,
+                        out_bias=True,
+                        qk_norm="rms_norm",
+                        residual_connection=True,
+                    )
+                    for _ in range(num_layers)
+                ]
+            )
+
+    def forward(
+        self,
+        hidden_states: torch.FloatTensor,
+        causal: bool = True,
+        timestep: Optional[torch.Tensor] = None,
+    ) -> torch.FloatTensor:
+        timestep_embed = None
+        if self.timestep_conditioning:
+            assert (
+                timestep is not None
+            ), "should pass timestep with timestep_conditioning=True"
+            batch_size = hidden_states.shape[0]
+            timestep_embed = self.time_embedder(
+                timestep=timestep.flatten(),
+                resolution=None,
+                aspect_ratio=None,
+                batch_size=batch_size,
+                hidden_dtype=hidden_states.dtype,
+            )
+            timestep_embed = timestep_embed.view(
+                batch_size, timestep_embed.shape[-1], 1, 1, 1
+            )
+
+        if self.attention_blocks:
+            for resnet, attention in zip(self.res_blocks, self.attention_blocks):
+                hidden_states = resnet(
+                    hidden_states, causal=causal, timestep=timestep_embed
+                )
+
+                # Reshape the hidden states to be (batch_size, frames * height * width, channel)
+                batch_size, channel, frames, height, width = hidden_states.shape
+                hidden_states = hidden_states.view(
+                    batch_size, channel, frames * height * width
+                ).transpose(1, 2)
+
+                if attention.use_tpu_flash_attention:
+                    # Pad the second dimension to be divisible by block_k_major (block in flash attention)
+                    seq_len = hidden_states.shape[1]
+                    block_k_major = 512
+                    pad_len = (block_k_major - seq_len % block_k_major) % block_k_major
+                    if pad_len > 0:
+                        hidden_states = F.pad(
+                            hidden_states, (0, 0, 0, pad_len), "constant", 0
+                        )
+
+                    # Create a mask with ones for the original sequence length and zeros for the padded indexes
+                    mask = torch.ones(
+                        (hidden_states.shape[0], seq_len),
+                        device=hidden_states.device,
+                        dtype=hidden_states.dtype,
+                    )
+                    if pad_len > 0:
+                        mask = F.pad(mask, (0, pad_len), "constant", 0)
+
+                hidden_states = attention(
+                    hidden_states,
+                    attention_mask=(
+                        None if not attention.use_tpu_flash_attention else mask
+                    ),
+                )
+
+                if attention.use_tpu_flash_attention:
+                    # Remove the padding
+                    if pad_len > 0:
+                        hidden_states = hidden_states[:, :-pad_len, :]
+
+                # Reshape the hidden states back to (batch_size, channel, frames, height, width, channel)
+                hidden_states = hidden_states.transpose(-1, -2).reshape(
+                    batch_size, channel, frames, height, width
+                )
+        else:
+            for resnet in self.res_blocks:
+                hidden_states = resnet(
+                    hidden_states, causal=causal, timestep=timestep_embed
+                )
+
+        return hidden_states
+
+
+class SpaceToDepthDownsample(nn.Module):
+    def __init__(self, dims, in_channels, out_channels, stride, spatial_padding_mode):
+        super().__init__()
+        self.stride = stride
+        self.group_size = in_channels * np.prod(stride) // out_channels
+        self.conv = make_conv_nd(
+            dims=dims,
+            in_channels=in_channels,
+            out_channels=out_channels // np.prod(stride),
+            kernel_size=3,
+            stride=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+    def forward(self, x, causal: bool = True):
+        if self.stride[0] == 2:
+            x = torch.cat(
+                [x[:, :, :1, :, :], x], dim=2
+            )  # duplicate first frames for padding
+
+        # skip connection
+        x_in = rearrange(
+            x,
+            "b c (d p1) (h p2) (w p3) -> b (c p1 p2 p3) d h w",
+            p1=self.stride[0],
+            p2=self.stride[1],
+            p3=self.stride[2],
+        )
+        x_in = rearrange(x_in, "b (c g) d h w -> b c g d h w", g=self.group_size)
+        x_in = x_in.mean(dim=2)
+
+        # conv
+        x = self.conv(x, causal=causal)
+        x = rearrange(
+            x,
+            "b c (d p1) (h p2) (w p3) -> b (c p1 p2 p3) d h w",
+            p1=self.stride[0],
+            p2=self.stride[1],
+            p3=self.stride[2],
+        )
+
+        x = x + x_in
+
+        return x
+
+
+class DepthToSpaceUpsample(nn.Module):
+    def __init__(
+        self,
+        dims,
+        in_channels,
+        stride,
+        residual=False,
+        out_channels_reduction_factor=1,
+        spatial_padding_mode="zeros",
+    ):
+        super().__init__()
+        self.stride = stride
+        self.out_channels = (
+            np.prod(stride) * in_channels // out_channels_reduction_factor
+        )
+        self.conv = make_conv_nd(
+            dims=dims,
+            in_channels=in_channels,
+            out_channels=self.out_channels,
+            kernel_size=3,
+            stride=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+        self.pixel_shuffle = PixelShuffleND(dims=dims, upscale_factors=stride)
+        self.residual = residual
+        self.out_channels_reduction_factor = out_channels_reduction_factor
+
+    def forward(self, x, causal: bool = True):
+        if self.residual:
+            # Reshape and duplicate the input to match the output shape
+            x_in = self.pixel_shuffle(x)
+            num_repeat = np.prod(self.stride) // self.out_channels_reduction_factor
+            x_in = x_in.repeat(1, num_repeat, 1, 1, 1)
+            if self.stride[0] == 2:
+                x_in = x_in[:, :, 1:, :, :]
+        x = self.conv(x, causal=causal)
+        x = self.pixel_shuffle(x)
+        if self.stride[0] == 2:
+            x = x[:, :, 1:, :, :]
+        if self.residual:
+            x = x + x_in
+        return x
+
+
+class LayerNorm(nn.Module):
+    def __init__(self, dim, eps, elementwise_affine=True) -> None:
+        super().__init__()
+        self.norm = nn.LayerNorm(dim, eps=eps, elementwise_affine=elementwise_affine)
+
+    def forward(self, x):
+        x = rearrange(x, "b c d h w -> b d h w c")
+        x = self.norm(x)
+        x = rearrange(x, "b d h w c -> b c d h w")
+        return x
+
+
+class ResnetBlock3D(nn.Module):
+    r"""
+    A Resnet block.
+
+    Parameters:
+        in_channels (`int`): The number of channels in the input.
+        out_channels (`int`, *optional*, default to be `None`):
+            The number of output channels for the first conv layer. If None, same as `in_channels`.
+        dropout (`float`, *optional*, defaults to `0.0`): The dropout probability to use.
+        groups (`int`, *optional*, default to `32`): The number of groups to use for the first normalization layer.
+        eps (`float`, *optional*, defaults to `1e-6`): The epsilon to use for the normalization.
+    """
+
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]],
+        in_channels: int,
+        out_channels: Optional[int] = None,
+        dropout: float = 0.0,
+        groups: int = 32,
+        eps: float = 1e-6,
+        norm_layer: str = "group_norm",
+        inject_noise: bool = False,
+        timestep_conditioning: bool = False,
+        spatial_padding_mode: str = "zeros",
+    ):
+        super().__init__()
+        self.in_channels = in_channels
+        out_channels = in_channels if out_channels is None else out_channels
+        self.out_channels = out_channels
+        self.inject_noise = inject_noise
+
+        if norm_layer == "group_norm":
+            self.norm1 = nn.GroupNorm(
+                num_groups=groups, num_channels=in_channels, eps=eps, affine=True
+            )
+        elif norm_layer == "pixel_norm":
+            self.norm1 = PixelNorm()
+        elif norm_layer == "layer_norm":
+            self.norm1 = LayerNorm(in_channels, eps=eps, elementwise_affine=True)
+
+        self.non_linearity = nn.SiLU()
+
+        self.conv1 = make_conv_nd(
+            dims,
+            in_channels,
+            out_channels,
+            kernel_size=3,
+            stride=1,
+            padding=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+        if inject_noise:
+            self.per_channel_scale1 = nn.Parameter(torch.zeros((in_channels, 1, 1)))
+
+        if norm_layer == "group_norm":
+            self.norm2 = nn.GroupNorm(
+                num_groups=groups, num_channels=out_channels, eps=eps, affine=True
+            )
+        elif norm_layer == "pixel_norm":
+            self.norm2 = PixelNorm()
+        elif norm_layer == "layer_norm":
+            self.norm2 = LayerNorm(out_channels, eps=eps, elementwise_affine=True)
+
+        self.dropout = torch.nn.Dropout(dropout)
+
+        self.conv2 = make_conv_nd(
+            dims,
+            out_channels,
+            out_channels,
+            kernel_size=3,
+            stride=1,
+            padding=1,
+            causal=True,
+            spatial_padding_mode=spatial_padding_mode,
+        )
+
+        if inject_noise:
+            self.per_channel_scale2 = nn.Parameter(torch.zeros((in_channels, 1, 1)))
+
+        self.conv_shortcut = (
+            make_linear_nd(
+                dims=dims, in_channels=in_channels, out_channels=out_channels
+            )
+            if in_channels != out_channels
+            else nn.Identity()
+        )
+
+        self.norm3 = (
+            LayerNorm(in_channels, eps=eps, elementwise_affine=True)
+            if in_channels != out_channels
+            else nn.Identity()
+        )
+
+        self.timestep_conditioning = timestep_conditioning
+
+        if timestep_conditioning:
+            self.scale_shift_table = nn.Parameter(
+                torch.randn(4, in_channels) / in_channels**0.5
+            )
+
+    def _feed_spatial_noise(
+        self, hidden_states: torch.FloatTensor, per_channel_scale: torch.FloatTensor
+    ) -> torch.FloatTensor:
+        spatial_shape = hidden_states.shape[-2:]
+        device = hidden_states.device
+        dtype = hidden_states.dtype
+
+        # similar to the "explicit noise inputs" method in style-gan
+        spatial_noise = torch.randn(spatial_shape, device=device, dtype=dtype)[None]
+        scaled_noise = (spatial_noise * per_channel_scale)[None, :, None, ...]
+        hidden_states = hidden_states + scaled_noise
+
+        return hidden_states
+
+    def forward(
+        self,
+        input_tensor: torch.FloatTensor,
+        causal: bool = True,
+        timestep: Optional[torch.Tensor] = None,
+    ) -> torch.FloatTensor:
+        hidden_states = input_tensor
+        batch_size = hidden_states.shape[0]
+
+        hidden_states = self.norm1(hidden_states)
+        if self.timestep_conditioning:
+            assert (
+                timestep is not None
+            ), "should pass timestep with timestep_conditioning=True"
+            ada_values = self.scale_shift_table[
+                None, ..., None, None, None
+            ] + timestep.reshape(
+                batch_size,
+                4,
+                -1,
+                timestep.shape[-3],
+                timestep.shape[-2],
+                timestep.shape[-1],
+            )
+            shift1, scale1, shift2, scale2 = ada_values.unbind(dim=1)
+
+            hidden_states = hidden_states * (1 + scale1) + shift1
+
+        hidden_states = self.non_linearity(hidden_states)
+
+        hidden_states = self.conv1(hidden_states, causal=causal)
+
+        if self.inject_noise:
+            hidden_states = self._feed_spatial_noise(
+                hidden_states, self.per_channel_scale1
+            )
+
+        hidden_states = self.norm2(hidden_states)
+
+        if self.timestep_conditioning:
+            hidden_states = hidden_states * (1 + scale2) + shift2
+
+        hidden_states = self.non_linearity(hidden_states)
+
+        hidden_states = self.dropout(hidden_states)
+
+        hidden_states = self.conv2(hidden_states, causal=causal)
+
+        if self.inject_noise:
+            hidden_states = self._feed_spatial_noise(
+                hidden_states, self.per_channel_scale2
+            )
+
+        input_tensor = self.norm3(input_tensor)
+
+        batch_size = input_tensor.shape[0]
+
+        input_tensor = self.conv_shortcut(input_tensor)
+
+        output_tensor = input_tensor + hidden_states
+
+        return output_tensor
+
+
+def patchify(x, patch_size_hw, patch_size_t=1):
+    if patch_size_hw == 1 and patch_size_t == 1:
+        return x
+    if x.dim() == 4:
+        x = rearrange(
+            x, "b c (h q) (w r) -> b (c r q) h w", q=patch_size_hw, r=patch_size_hw
+        )
+    elif x.dim() == 5:
+        x = rearrange(
+            x,
+            "b c (f p) (h q) (w r) -> b (c p r q) f h w",
+            p=patch_size_t,
+            q=patch_size_hw,
+            r=patch_size_hw,
+        )
+    else:
+        raise ValueError(f"Invalid input shape: {x.shape}")
+
+    return x
+
+
+def unpatchify(x, patch_size_hw, patch_size_t=1):
+    if patch_size_hw == 1 and patch_size_t == 1:
+        return x
+
+    if x.dim() == 4:
+        x = rearrange(
+            x, "b (c r q) h w -> b c (h q) (w r)", q=patch_size_hw, r=patch_size_hw
+        )
+    elif x.dim() == 5:
+        x = rearrange(
+            x,
+            "b (c p r q) f h w -> b c (f p) (h q) (w r)",
+            p=patch_size_t,
+            q=patch_size_hw,
+            r=patch_size_hw,
+        )
+
+    return x
+
+
+def create_video_autoencoder_demo_config(
+    latent_channels: int = 64,
+):
+    encoder_blocks = [
+        ("res_x", {"num_layers": 2}),
+        ("compress_space_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 2}),
+        ("compress_time_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 1}),
+        ("compress_all_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 1}),
+        ("compress_all_res", {"multiplier": 2}),
+        ("res_x", {"num_layers": 1}),
+    ]
+    decoder_blocks = [
+        ("res_x", {"num_layers": 2, "inject_noise": False}),
+        ("compress_all", {"residual": True, "multiplier": 2}),
+        ("res_x", {"num_layers": 2, "inject_noise": False}),
+        ("compress_all", {"residual": True, "multiplier": 2}),
+        ("res_x", {"num_layers": 2, "inject_noise": False}),
+        ("compress_all", {"residual": True, "multiplier": 2}),
+        ("res_x", {"num_layers": 2, "inject_noise": False}),
+    ]
+    return {
+        "_class_name": "CausalVideoAutoencoder",
+        "dims": 3,
+        "encoder_blocks": encoder_blocks,
+        "decoder_blocks": decoder_blocks,
+        "latent_channels": latent_channels,
+        "norm_layer": "pixel_norm",
+        "patch_size": 4,
+        "latent_log_var": "uniform",
+        "use_quant_conv": False,
+        "causal_decoder": False,
+        "timestep_conditioning": True,
+        "spatial_padding_mode": "replicate",
+    }
+
+
+def test_vae_patchify_unpatchify():
+    import torch
+
+    x = torch.randn(2, 3, 8, 64, 64)
+    x_patched = patchify(x, patch_size_hw=4, patch_size_t=4)
+    x_unpatched = unpatchify(x_patched, patch_size_hw=4, patch_size_t=4)
+    assert torch.allclose(x, x_unpatched)
+
+
+def demo_video_autoencoder_forward_backward():
+    # Configuration for the VideoAutoencoder
+    config = create_video_autoencoder_demo_config()
+
+    # Instantiate the VideoAutoencoder with the specified configuration
+    video_autoencoder = CausalVideoAutoencoder.from_config(config)
+
+    print(video_autoencoder)
+    video_autoencoder.eval()
+    # Print the total number of parameters in the video autoencoder
+    total_params = sum(p.numel() for p in video_autoencoder.parameters())
+    print(f"Total number of parameters in VideoAutoencoder: {total_params:,}")
+
+    # Create a mock input tensor simulating a batch of videos
+    # Shape: (batch_size, channels, depth, height, width)
+    # E.g., 4 videos, each with 3 color channels, 16 frames, and 64x64 pixels per frame
+    input_videos = torch.randn(2, 3, 17, 64, 64)
+
+    # Forward pass: encode and decode the input videos
+    latent = video_autoencoder.encode(input_videos).latent_dist.mode()
+    print(f"input shape={input_videos.shape}")
+    print(f"latent shape={latent.shape}")
+
+    timestep = torch.ones(input_videos.shape[0]) * 0.1
+    reconstructed_videos = video_autoencoder.decode(
+        latent, target_shape=input_videos.shape, timestep=timestep
+    ).sample
+
+    print(f"reconstructed shape={reconstructed_videos.shape}")
+
+    # Validate that single image gets treated the same way as first frame
+    input_image = input_videos[:, :, :1, :, :]
+    image_latent = video_autoencoder.encode(input_image).latent_dist.mode()
+    _ = video_autoencoder.decode(
+        image_latent, target_shape=image_latent.shape, timestep=timestep
+    ).sample
+
+    first_frame_latent = latent[:, :, :1, :, :]
+
+    assert torch.allclose(image_latent, first_frame_latent, atol=1e-6)
+    # assert torch.allclose(reconstructed_image, reconstructed_videos[:, :, :1, :, :], atol=1e-6)
+    # assert torch.allclose(image_latent, first_frame_latent, atol=1e-6)
+    # assert (reconstructed_image == reconstructed_videos[:, :, :1, :, :]).all()
+
+    # Calculate the loss (e.g., mean squared error)
+    loss = torch.nn.functional.mse_loss(input_videos, reconstructed_videos)
+
+    # Perform backward pass
+    loss.backward()
+
+    print(f"Demo completed with loss: {loss.item()}")
+
+
+# Ensure to call the demo function to execute the forward and backward pass
+if __name__ == "__main__":
+    demo_video_autoencoder_forward_backward()

ltx_video/models/autoencoders/conv_nd_factory.py

@@ -0,0 +1,90 @@
+from typing import Tuple, Union
+
+import torch
+
+from ltx_video.models.autoencoders.dual_conv3d import DualConv3d
+from ltx_video.models.autoencoders.causal_conv3d import CausalConv3d
+
+
+def make_conv_nd(
+    dims: Union[int, Tuple[int, int]],
+    in_channels: int,
+    out_channels: int,
+    kernel_size: int,
+    stride=1,
+    padding=0,
+    dilation=1,
+    groups=1,
+    bias=True,
+    causal=False,
+    spatial_padding_mode="zeros",
+    temporal_padding_mode="zeros",
+):
+    if not (spatial_padding_mode == temporal_padding_mode or causal):
+        raise NotImplementedError("spatial and temporal padding modes must be equal")
+    if dims == 2:
+        return torch.nn.Conv2d(
+            in_channels=in_channels,
+            out_channels=out_channels,
+            kernel_size=kernel_size,
+            stride=stride,
+            padding=padding,
+            dilation=dilation,
+            groups=groups,
+            bias=bias,
+            padding_mode=spatial_padding_mode,
+        )
+    elif dims == 3:
+        if causal:
+            return CausalConv3d(
+                in_channels=in_channels,
+                out_channels=out_channels,
+                kernel_size=kernel_size,
+                stride=stride,
+                padding=padding,
+                dilation=dilation,
+                groups=groups,
+                bias=bias,
+                spatial_padding_mode=spatial_padding_mode,
+            )
+        return torch.nn.Conv3d(
+            in_channels=in_channels,
+            out_channels=out_channels,
+            kernel_size=kernel_size,
+            stride=stride,
+            padding=padding,
+            dilation=dilation,
+            groups=groups,
+            bias=bias,
+            padding_mode=spatial_padding_mode,
+        )
+    elif dims == (2, 1):
+        return DualConv3d(
+            in_channels=in_channels,
+            out_channels=out_channels,
+            kernel_size=kernel_size,
+            stride=stride,
+            padding=padding,
+            bias=bias,
+            padding_mode=spatial_padding_mode,
+        )
+    else:
+        raise ValueError(f"unsupported dimensions: {dims}")
+
+
+def make_linear_nd(
+    dims: int,
+    in_channels: int,
+    out_channels: int,
+    bias=True,
+):
+    if dims == 2:
+        return torch.nn.Conv2d(
+            in_channels=in_channels, out_channels=out_channels, kernel_size=1, bias=bias
+        )
+    elif dims == 3 or dims == (2, 1):
+        return torch.nn.Conv3d(
+            in_channels=in_channels, out_channels=out_channels, kernel_size=1, bias=bias
+        )
+    else:
+        raise ValueError(f"unsupported dimensions: {dims}")

ltx_video/models/autoencoders/dual_conv3d.py

@@ -0,0 +1,217 @@
+import math
+from typing import Tuple, Union
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from einops import rearrange
+
+
+class DualConv3d(nn.Module):
+    def __init__(
+        self,
+        in_channels,
+        out_channels,
+        kernel_size,
+        stride: Union[int, Tuple[int, int, int]] = 1,
+        padding: Union[int, Tuple[int, int, int]] = 0,
+        dilation: Union[int, Tuple[int, int, int]] = 1,
+        groups=1,
+        bias=True,
+        padding_mode="zeros",
+    ):
+        super(DualConv3d, self).__init__()
+
+        self.in_channels = in_channels
+        self.out_channels = out_channels
+        self.padding_mode = padding_mode
+        # Ensure kernel_size, stride, padding, and dilation are tuples of length 3
+        if isinstance(kernel_size, int):
+            kernel_size = (kernel_size, kernel_size, kernel_size)
+        if kernel_size == (1, 1, 1):
+            raise ValueError(
+                "kernel_size must be greater than 1. Use make_linear_nd instead."
+            )
+        if isinstance(stride, int):
+            stride = (stride, stride, stride)
+        if isinstance(padding, int):
+            padding = (padding, padding, padding)
+        if isinstance(dilation, int):
+            dilation = (dilation, dilation, dilation)
+
+        # Set parameters for convolutions
+        self.groups = groups
+        self.bias = bias
+
+        # Define the size of the channels after the first convolution
+        intermediate_channels = (
+            out_channels if in_channels < out_channels else in_channels
+        )
+
+        # Define parameters for the first convolution
+        self.weight1 = nn.Parameter(
+            torch.Tensor(
+                intermediate_channels,
+                in_channels // groups,
+                1,
+                kernel_size[1],
+                kernel_size[2],
+            )
+        )
+        self.stride1 = (1, stride[1], stride[2])
+        self.padding1 = (0, padding[1], padding[2])
+        self.dilation1 = (1, dilation[1], dilation[2])
+        if bias:
+            self.bias1 = nn.Parameter(torch.Tensor(intermediate_channels))
+        else:
+            self.register_parameter("bias1", None)
+
+        # Define parameters for the second convolution
+        self.weight2 = nn.Parameter(
+            torch.Tensor(
+                out_channels, intermediate_channels // groups, kernel_size[0], 1, 1
+            )
+        )
+        self.stride2 = (stride[0], 1, 1)
+        self.padding2 = (padding[0], 0, 0)
+        self.dilation2 = (dilation[0], 1, 1)
+        if bias:
+            self.bias2 = nn.Parameter(torch.Tensor(out_channels))
+        else:
+            self.register_parameter("bias2", None)
+
+        # Initialize weights and biases
+        self.reset_parameters()
+
+    def reset_parameters(self):
+        nn.init.kaiming_uniform_(self.weight1, a=math.sqrt(5))
+        nn.init.kaiming_uniform_(self.weight2, a=math.sqrt(5))
+        if self.bias:
+            fan_in1, _ = nn.init._calculate_fan_in_and_fan_out(self.weight1)
+            bound1 = 1 / math.sqrt(fan_in1)
+            nn.init.uniform_(self.bias1, -bound1, bound1)
+            fan_in2, _ = nn.init._calculate_fan_in_and_fan_out(self.weight2)
+            bound2 = 1 / math.sqrt(fan_in2)
+            nn.init.uniform_(self.bias2, -bound2, bound2)
+
+    def forward(self, x, use_conv3d=False, skip_time_conv=False):
+        if use_conv3d:
+            return self.forward_with_3d(x=x, skip_time_conv=skip_time_conv)
+        else:
+            return self.forward_with_2d(x=x, skip_time_conv=skip_time_conv)
+
+    def forward_with_3d(self, x, skip_time_conv):
+        # First convolution
+        x = F.conv3d(
+            x,
+            self.weight1,
+            self.bias1,
+            self.stride1,
+            self.padding1,
+            self.dilation1,
+            self.groups,
+            padding_mode=self.padding_mode,
+        )
+
+        if skip_time_conv:
+            return x
+
+        # Second convolution
+        x = F.conv3d(
+            x,
+            self.weight2,
+            self.bias2,
+            self.stride2,
+            self.padding2,
+            self.dilation2,
+            self.groups,
+            padding_mode=self.padding_mode,
+        )
+
+        return x
+
+    def forward_with_2d(self, x, skip_time_conv):
+        b, c, d, h, w = x.shape
+
+        # First 2D convolution
+        x = rearrange(x, "b c d h w -> (b d) c h w")
+        # Squeeze the depth dimension out of weight1 since it's 1
+        weight1 = self.weight1.squeeze(2)
+        # Select stride, padding, and dilation for the 2D convolution
+        stride1 = (self.stride1[1], self.stride1[2])
+        padding1 = (self.padding1[1], self.padding1[2])
+        dilation1 = (self.dilation1[1], self.dilation1[2])
+        x = F.conv2d(
+            x,
+            weight1,
+            self.bias1,
+            stride1,
+            padding1,
+            dilation1,
+            self.groups,
+            padding_mode=self.padding_mode,
+        )
+
+        _, _, h, w = x.shape
+
+        if skip_time_conv:
+            x = rearrange(x, "(b d) c h w -> b c d h w", b=b)
+            return x
+
+        # Second convolution which is essentially treated as a 1D convolution across the 'd' dimension
+        x = rearrange(x, "(b d) c h w -> (b h w) c d", b=b)
+
+        # Reshape weight2 to match the expected dimensions for conv1d
+        weight2 = self.weight2.squeeze(-1).squeeze(-1)
+        # Use only the relevant dimension for stride, padding, and dilation for the 1D convolution
+        stride2 = self.stride2[0]
+        padding2 = self.padding2[0]
+        dilation2 = self.dilation2[0]
+        x = F.conv1d(
+            x,
+            weight2,
+            self.bias2,
+            stride2,
+            padding2,
+            dilation2,
+            self.groups,
+            padding_mode=self.padding_mode,
+        )
+        x = rearrange(x, "(b h w) c d -> b c d h w", b=b, h=h, w=w)
+
+        return x
+
+    @property
+    def weight(self):
+        return self.weight2
+
+
+def test_dual_conv3d_consistency():
+    # Initialize parameters
+    in_channels = 3
+    out_channels = 5
+    kernel_size = (3, 3, 3)
+    stride = (2, 2, 2)
+    padding = (1, 1, 1)
+
+    # Create an instance of the DualConv3d class
+    dual_conv3d = DualConv3d(
+        in_channels=in_channels,
+        out_channels=out_channels,
+        kernel_size=kernel_size,
+        stride=stride,
+        padding=padding,
+        bias=True,
+    )
+
+    # Example input tensor
+    test_input = torch.randn(1, 3, 10, 10, 10)
+
+    # Perform forward passes with both 3D and 2D settings
+    output_conv3d = dual_conv3d(test_input, use_conv3d=True)
+    output_2d = dual_conv3d(test_input, use_conv3d=False)
+
+    # Assert that the outputs from both methods are sufficiently close
+    assert torch.allclose(
+        output_conv3d, output_2d, atol=1e-6
+    ), "Outputs are not consistent between 3D and 2D convolutions."

ltx_video/models/autoencoders/latent_upsampler.py

@@ -0,0 +1,203 @@
+from typing import Optional, Union
+from pathlib import Path
+import os
+import json
+
+import torch
+import torch.nn as nn
+from einops import rearrange
+from diffusers import ConfigMixin, ModelMixin
+from safetensors.torch import safe_open
+
+from ltx_video.models.autoencoders.pixel_shuffle import PixelShuffleND
+
+
+class ResBlock(nn.Module):
+    def __init__(
+        self, channels: int, mid_channels: Optional[int] = None, dims: int = 3
+    ):
+        super().__init__()
+        if mid_channels is None:
+            mid_channels = channels
+
+        Conv = nn.Conv2d if dims == 2 else nn.Conv3d
+
+        self.conv1 = Conv(channels, mid_channels, kernel_size=3, padding=1)
+        self.norm1 = nn.GroupNorm(32, mid_channels)
+        self.conv2 = Conv(mid_channels, channels, kernel_size=3, padding=1)
+        self.norm2 = nn.GroupNorm(32, channels)
+        self.activation = nn.SiLU()
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        residual = x
+        x = self.conv1(x)
+        x = self.norm1(x)
+        x = self.activation(x)
+        x = self.conv2(x)
+        x = self.norm2(x)
+        x = self.activation(x + residual)
+        return x
+
+
+class LatentUpsampler(ModelMixin, ConfigMixin):
+    """
+    Model to spatially upsample VAE latents.
+
+    Args:
+        in_channels (`int`): Number of channels in the input latent
+        mid_channels (`int`): Number of channels in the middle layers
+        num_blocks_per_stage (`int`): Number of ResBlocks to use in each stage (pre/post upsampling)
+        dims (`int`): Number of dimensions for convolutions (2 or 3)
+        spatial_upsample (`bool`): Whether to spatially upsample the latent
+        temporal_upsample (`bool`): Whether to temporally upsample the latent
+    """
+
+    def __init__(
+        self,
+        in_channels: int = 128,
+        mid_channels: int = 512,
+        num_blocks_per_stage: int = 4,
+        dims: int = 3,
+        spatial_upsample: bool = True,
+        temporal_upsample: bool = False,
+    ):
+        super().__init__()
+
+        self.in_channels = in_channels
+        self.mid_channels = mid_channels
+        self.num_blocks_per_stage = num_blocks_per_stage
+        self.dims = dims
+        self.spatial_upsample = spatial_upsample
+        self.temporal_upsample = temporal_upsample
+
+        Conv = nn.Conv2d if dims == 2 else nn.Conv3d
+
+        self.initial_conv = Conv(in_channels, mid_channels, kernel_size=3, padding=1)
+        self.initial_norm = nn.GroupNorm(32, mid_channels)
+        self.initial_activation = nn.SiLU()
+
+        self.res_blocks = nn.ModuleList(
+            [ResBlock(mid_channels, dims=dims) for _ in range(num_blocks_per_stage)]
+        )
+
+        if spatial_upsample and temporal_upsample:
+            self.upsampler = nn.Sequential(
+                nn.Conv3d(mid_channels, 8 * mid_channels, kernel_size=3, padding=1),
+                PixelShuffleND(3),
+            )
+        elif spatial_upsample:
+            self.upsampler = nn.Sequential(
+                nn.Conv2d(mid_channels, 4 * mid_channels, kernel_size=3, padding=1),
+                PixelShuffleND(2),
+            )
+        elif temporal_upsample:
+            self.upsampler = nn.Sequential(
+                nn.Conv3d(mid_channels, 2 * mid_channels, kernel_size=3, padding=1),
+                PixelShuffleND(1),
+            )
+        else:
+            raise ValueError(
+                "Either spatial_upsample or temporal_upsample must be True"
+            )
+
+        self.post_upsample_res_blocks = nn.ModuleList(
+            [ResBlock(mid_channels, dims=dims) for _ in range(num_blocks_per_stage)]
+        )
+
+        self.final_conv = Conv(mid_channels, in_channels, kernel_size=3, padding=1)
+
+    def forward(self, latent: torch.Tensor) -> torch.Tensor:
+        b, c, f, h, w = latent.shape
+
+        if self.dims == 2:
+            x = rearrange(latent, "b c f h w -> (b f) c h w")
+            x = self.initial_conv(x)
+            x = self.initial_norm(x)
+            x = self.initial_activation(x)
+
+            for block in self.res_blocks:
+                x = block(x)
+
+            x = self.upsampler(x)
+
+            for block in self.post_upsample_res_blocks:
+                x = block(x)
+
+            x = self.final_conv(x)
+            x = rearrange(x, "(b f) c h w -> b c f h w", b=b, f=f)
+        else:
+            x = self.initial_conv(latent)
+            x = self.initial_norm(x)
+            x = self.initial_activation(x)
+
+            for block in self.res_blocks:
+                x = block(x)
+
+            if self.temporal_upsample:
+                x = self.upsampler(x)
+                x = x[:, :, 1:, :, :]
+            else:
+                x = rearrange(x, "b c f h w -> (b f) c h w")
+                x = self.upsampler(x)
+                x = rearrange(x, "(b f) c h w -> b c f h w", b=b, f=f)
+
+            for block in self.post_upsample_res_blocks:
+                x = block(x)
+
+            x = self.final_conv(x)
+
+        return x
+
+    @classmethod
+    def from_config(cls, config):
+        return cls(
+            in_channels=config.get("in_channels", 4),
+            mid_channels=config.get("mid_channels", 128),
+            num_blocks_per_stage=config.get("num_blocks_per_stage", 4),
+            dims=config.get("dims", 2),
+            spatial_upsample=config.get("spatial_upsample", True),
+            temporal_upsample=config.get("temporal_upsample", False),
+        )
+
+    def config(self):
+        return {
+            "_class_name": "LatentUpsampler",
+            "in_channels": self.in_channels,
+            "mid_channels": self.mid_channels,
+            "num_blocks_per_stage": self.num_blocks_per_stage,
+            "dims": self.dims,
+            "spatial_upsample": self.spatial_upsample,
+            "temporal_upsample": self.temporal_upsample,
+        }
+
+    @classmethod
+    def from_pretrained(
+        cls,
+        pretrained_model_path: Optional[Union[str, os.PathLike]],
+        *args,
+        **kwargs,
+    ):
+        pretrained_model_path = Path(pretrained_model_path)
+        if pretrained_model_path.is_file() and str(pretrained_model_path).endswith(
+            ".safetensors"
+        ):
+            state_dict = {}
+            with safe_open(pretrained_model_path, framework="pt", device="cpu") as f:
+                metadata = f.metadata()
+                for k in f.keys():
+                    state_dict[k] = f.get_tensor(k)
+            config = json.loads(metadata["config"])
+            with torch.device("meta"):
+                latent_upsampler = LatentUpsampler.from_config(config)
+            latent_upsampler.load_state_dict(state_dict, assign=True)
+        return latent_upsampler
+
+
+if __name__ == "__main__":
+    latent_upsampler = LatentUpsampler(num_blocks_per_stage=4, dims=3)
+    print(latent_upsampler)
+    total_params = sum(p.numel() for p in latent_upsampler.parameters())
+    print(f"Total number of parameters: {total_params:,}")
+    latent = torch.randn(1, 128, 9, 16, 16)
+    upsampled_latent = latent_upsampler(latent)
+    print(f"Upsampled latent shape: {upsampled_latent.shape}")

ltx_video/models/autoencoders/pixel_norm.py

@@ -0,0 +1,12 @@
+import torch
+from torch import nn
+
+
+class PixelNorm(nn.Module):
+    def __init__(self, dim=1, eps=1e-8):
+        super(PixelNorm, self).__init__()
+        self.dim = dim
+        self.eps = eps
+
+    def forward(self, x):
+        return x / torch.sqrt(torch.mean(x**2, dim=self.dim, keepdim=True) + self.eps)

ltx_video/models/autoencoders/pixel_shuffle.py

@@ -0,0 +1,33 @@
+import torch.nn as nn
+from einops import rearrange
+
+
+class PixelShuffleND(nn.Module):
+    def __init__(self, dims, upscale_factors=(2, 2, 2)):
+        super().__init__()
+        assert dims in [1, 2, 3], "dims must be 1, 2, or 3"
+        self.dims = dims
+        self.upscale_factors = upscale_factors
+
+    def forward(self, x):
+        if self.dims == 3:
+            return rearrange(
+                x,
+                "b (c p1 p2 p3) d h w -> b c (d p1) (h p2) (w p3)",
+                p1=self.upscale_factors[0],
+                p2=self.upscale_factors[1],
+                p3=self.upscale_factors[2],
+            )
+        elif self.dims == 2:
+            return rearrange(
+                x,
+                "b (c p1 p2) h w -> b c (h p1) (w p2)",
+                p1=self.upscale_factors[0],
+                p2=self.upscale_factors[1],
+            )
+        elif self.dims == 1:
+            return rearrange(
+                x,
+                "b (c p1) f h w -> b c (f p1) h w",
+                p1=self.upscale_factors[0],
+            )

ltx_video/models/autoencoders/vae.py

@@ -0,0 +1,380 @@
+from typing import Optional, Union
+
+import torch
+import inspect
+import math
+import torch.nn as nn
+from diffusers import ConfigMixin, ModelMixin
+from diffusers.models.autoencoders.vae import (
+    DecoderOutput,
+    DiagonalGaussianDistribution,
+)
+from diffusers.models.modeling_outputs import AutoencoderKLOutput
+from ltx_video.models.autoencoders.conv_nd_factory import make_conv_nd
+
+
+class AutoencoderKLWrapper(ModelMixin, ConfigMixin):
+    """Variational Autoencoder (VAE) model with KL loss.
+
+    VAE from the paper Auto-Encoding Variational Bayes by Diederik P. Kingma and Max Welling.
+    This model is a wrapper around an encoder and a decoder, and it adds a KL loss term to the reconstruction loss.
+
+    Args:
+        encoder (`nn.Module`):
+            Encoder module.
+        decoder (`nn.Module`):
+            Decoder module.
+        latent_channels (`int`, *optional*, defaults to 4):
+            Number of latent channels.
+    """
+
+    def __init__(
+        self,
+        encoder: nn.Module,
+        decoder: nn.Module,
+        latent_channels: int = 4,
+        dims: int = 2,
+        sample_size=512,
+        use_quant_conv: bool = True,
+        normalize_latent_channels: bool = False,
+    ):
+        super().__init__()
+
+        # pass init params to Encoder
+        self.encoder = encoder
+        self.use_quant_conv = use_quant_conv
+        self.normalize_latent_channels = normalize_latent_channels
+
+        # pass init params to Decoder
+        quant_dims = 2 if dims == 2 else 3
+        self.decoder = decoder
+        if use_quant_conv:
+            self.quant_conv = make_conv_nd(
+                quant_dims, 2 * latent_channels, 2 * latent_channels, 1
+            )
+            self.post_quant_conv = make_conv_nd(
+                quant_dims, latent_channels, latent_channels, 1
+            )
+        else:
+            self.quant_conv = nn.Identity()
+            self.post_quant_conv = nn.Identity()
+
+        if normalize_latent_channels:
+            if dims == 2:
+                self.latent_norm_out = nn.BatchNorm2d(latent_channels, affine=False)
+            else:
+                self.latent_norm_out = nn.BatchNorm3d(latent_channels, affine=False)
+        else:
+            self.latent_norm_out = nn.Identity()
+        self.use_z_tiling = False
+        self.use_hw_tiling = False
+        self.dims = dims
+        self.z_sample_size = 1
+
+        self.decoder_params = inspect.signature(self.decoder.forward).parameters
+
+        # only relevant if vae tiling is enabled
+        self.set_tiling_params(sample_size=sample_size, overlap_factor=0.25)
+
+    def set_tiling_params(self, sample_size: int = 512, overlap_factor: float = 0.25):
+        self.tile_sample_min_size = sample_size
+        num_blocks = len(self.encoder.down_blocks)
+        self.tile_latent_min_size = int(sample_size / (2 ** (num_blocks - 1)))
+        self.tile_overlap_factor = overlap_factor
+
+    def enable_z_tiling(self, z_sample_size: int = 8):
+        r"""
+        Enable tiling during VAE decoding.
+
+        When this option is enabled, the VAE will split the input tensor in tiles to compute decoding in several
+        steps. This is useful to save some memory and allow larger batch sizes.
+        """
+        self.use_z_tiling = z_sample_size > 1
+        self.z_sample_size = z_sample_size
+        assert (
+            z_sample_size % 8 == 0 or z_sample_size == 1
+        ), f"z_sample_size must be a multiple of 8 or 1. Got {z_sample_size}."
+
+    def disable_z_tiling(self):
+        r"""
+        Disable tiling during VAE decoding. If `use_tiling` was previously invoked, this method will go back to computing
+        decoding in one step.
+        """
+        self.use_z_tiling = False
+
+    def enable_hw_tiling(self):
+        r"""
+        Enable tiling during VAE decoding along the height and width dimension.
+        """
+        self.use_hw_tiling = True
+
+    def disable_hw_tiling(self):
+        r"""
+        Disable tiling during VAE decoding along the height and width dimension.
+        """
+        self.use_hw_tiling = False
+
+    def _hw_tiled_encode(self, x: torch.FloatTensor, return_dict: bool = True):
+        overlap_size = int(self.tile_sample_min_size * (1 - self.tile_overlap_factor))
+        blend_extent = int(self.tile_latent_min_size * self.tile_overlap_factor)
+        row_limit = self.tile_latent_min_size - blend_extent
+
+        # Split the image into 512x512 tiles and encode them separately.
+        rows = []
+        for i in range(0, x.shape[3], overlap_size):
+            row = []
+            for j in range(0, x.shape[4], overlap_size):
+                tile = x[
+                    :,
+                    :,
+                    :,
+                    i : i + self.tile_sample_min_size,
+                    j : j + self.tile_sample_min_size,
+                ]
+                tile = self.encoder(tile)
+                tile = self.quant_conv(tile)
+                row.append(tile)
+            rows.append(row)
+        result_rows = []
+        for i, row in enumerate(rows):
+            result_row = []
+            for j, tile in enumerate(row):
+                # blend the above tile and the left tile
+                # to the current tile and add the current tile to the result row
+                if i > 0:
+                    tile = self.blend_v(rows[i - 1][j], tile, blend_extent)
+                if j > 0:
+                    tile = self.blend_h(row[j - 1], tile, blend_extent)
+                result_row.append(tile[:, :, :, :row_limit, :row_limit])
+            result_rows.append(torch.cat(result_row, dim=4))
+
+        moments = torch.cat(result_rows, dim=3)
+        return moments
+
+    def blend_z(
+        self, a: torch.Tensor, b: torch.Tensor, blend_extent: int
+    ) -> torch.Tensor:
+        blend_extent = min(a.shape[2], b.shape[2], blend_extent)
+        for z in range(blend_extent):
+            b[:, :, z, :, :] = a[:, :, -blend_extent + z, :, :] * (
+                1 - z / blend_extent
+            ) + b[:, :, z, :, :] * (z / blend_extent)
+        return b
+
+    def blend_v(
+        self, a: torch.Tensor, b: torch.Tensor, blend_extent: int
+    ) -> torch.Tensor:
+        blend_extent = min(a.shape[3], b.shape[3], blend_extent)
+        for y in range(blend_extent):
+            b[:, :, :, y, :] = a[:, :, :, -blend_extent + y, :] * (
+                1 - y / blend_extent
+            ) + b[:, :, :, y, :] * (y / blend_extent)
+        return b
+
+    def blend_h(
+        self, a: torch.Tensor, b: torch.Tensor, blend_extent: int
+    ) -> torch.Tensor:
+        blend_extent = min(a.shape[4], b.shape[4], blend_extent)
+        for x in range(blend_extent):
+            b[:, :, :, :, x] = a[:, :, :, :, -blend_extent + x] * (
+                1 - x / blend_extent
+            ) + b[:, :, :, :, x] * (x / blend_extent)
+        return b
+
+    def _hw_tiled_decode(self, z: torch.FloatTensor, target_shape):
+        overlap_size = int(self.tile_latent_min_size * (1 - self.tile_overlap_factor))
+        blend_extent = int(self.tile_sample_min_size * self.tile_overlap_factor)
+        row_limit = self.tile_sample_min_size - blend_extent
+        tile_target_shape = (
+            *target_shape[:3],
+            self.tile_sample_min_size,
+            self.tile_sample_min_size,
+        )
+        # Split z into overlapping 64x64 tiles and decode them separately.
+        # The tiles have an overlap to avoid seams between tiles.
+        rows = []
+        for i in range(0, z.shape[3], overlap_size):
+            row = []
+            for j in range(0, z.shape[4], overlap_size):
+                tile = z[
+                    :,
+                    :,
+                    :,
+                    i : i + self.tile_latent_min_size,
+                    j : j + self.tile_latent_min_size,
+                ]
+                tile = self.post_quant_conv(tile)
+                decoded = self.decoder(tile, target_shape=tile_target_shape)
+                row.append(decoded)
+            rows.append(row)
+        result_rows = []
+        for i, row in enumerate(rows):
+            result_row = []
+            for j, tile in enumerate(row):
+                # blend the above tile and the left tile
+                # to the current tile and add the current tile to the result row
+                if i > 0:
+                    tile = self.blend_v(rows[i - 1][j], tile, blend_extent)
+                if j > 0:
+                    tile = self.blend_h(row[j - 1], tile, blend_extent)
+                result_row.append(tile[:, :, :, :row_limit, :row_limit])
+            result_rows.append(torch.cat(result_row, dim=4))
+
+        dec = torch.cat(result_rows, dim=3)
+        return dec
+
+    def encode(
+        self, z: torch.FloatTensor, return_dict: bool = True
+    ) -> Union[DecoderOutput, torch.FloatTensor]:
+        if self.use_z_tiling and z.shape[2] > self.z_sample_size > 1:
+            num_splits = z.shape[2] // self.z_sample_size
+            sizes = [self.z_sample_size] * num_splits
+            sizes = (
+                sizes + [z.shape[2] - sum(sizes)]
+                if z.shape[2] - sum(sizes) > 0
+                else sizes
+            )
+            tiles = z.split(sizes, dim=2)
+            moments_tiles = [
+                (
+                    self._hw_tiled_encode(z_tile, return_dict)
+                    if self.use_hw_tiling
+                    else self._encode(z_tile)
+                )
+                for z_tile in tiles
+            ]
+            moments = torch.cat(moments_tiles, dim=2)
+
+        else:
+            moments = (
+                self._hw_tiled_encode(z, return_dict)
+                if self.use_hw_tiling
+                else self._encode(z)
+            )
+
+        posterior = DiagonalGaussianDistribution(moments)
+        if not return_dict:
+            return (posterior,)
+
+        return AutoencoderKLOutput(latent_dist=posterior)
+
+    def _normalize_latent_channels(self, z: torch.FloatTensor) -> torch.FloatTensor:
+        if isinstance(self.latent_norm_out, nn.BatchNorm3d):
+            _, c, _, _, _ = z.shape
+            z = torch.cat(
+                [
+                    self.latent_norm_out(z[:, : c // 2, :, :, :]),
+                    z[:, c // 2 :, :, :, :],
+                ],
+                dim=1,
+            )
+        elif isinstance(self.latent_norm_out, nn.BatchNorm2d):
+            raise NotImplementedError("BatchNorm2d not supported")
+        return z
+
+    def _unnormalize_latent_channels(self, z: torch.FloatTensor) -> torch.FloatTensor:
+        if isinstance(self.latent_norm_out, nn.BatchNorm3d):
+            running_mean = self.latent_norm_out.running_mean.view(1, -1, 1, 1, 1)
+            running_var = self.latent_norm_out.running_var.view(1, -1, 1, 1, 1)
+            eps = self.latent_norm_out.eps
+
+            z = z * torch.sqrt(running_var + eps) + running_mean
+        elif isinstance(self.latent_norm_out, nn.BatchNorm3d):
+            raise NotImplementedError("BatchNorm2d not supported")
+        return z
+
+    def _encode(self, x: torch.FloatTensor) -> AutoencoderKLOutput:
+        h = self.encoder(x)
+        moments = self.quant_conv(h)
+        moments = self._normalize_latent_channels(moments)
+        return moments
+
+    def _decode(
+        self,
+        z: torch.FloatTensor,
+        target_shape=None,
+        timestep: Optional[torch.Tensor] = None,
+    ) -> Union[DecoderOutput, torch.FloatTensor]:
+        z = self._unnormalize_latent_channels(z)
+        z = self.post_quant_conv(z)
+        if "timestep" in self.decoder_params:
+            dec = self.decoder(z, target_shape=target_shape, timestep=timestep)
+        else:
+            dec = self.decoder(z, target_shape=target_shape)
+        return dec
+
+    def decode(
+        self,
+        z: torch.FloatTensor,
+        return_dict: bool = True,
+        target_shape=None,
+        timestep: Optional[torch.Tensor] = None,
+    ) -> Union[DecoderOutput, torch.FloatTensor]:
+        assert target_shape is not None, "target_shape must be provided for decoding"
+        if self.use_z_tiling and z.shape[2] > self.z_sample_size > 1:
+            reduction_factor = int(
+                self.encoder.patch_size_t
+                * 2
+                ** (
+                    len(self.encoder.down_blocks)
+                    - 1
+                    - math.sqrt(self.encoder.patch_size)
+                )
+            )
+            split_size = self.z_sample_size // reduction_factor
+            num_splits = z.shape[2] // split_size
+
+            # copy target shape, and divide frame dimension (=2) by the context size
+            target_shape_split = list(target_shape)
+            target_shape_split[2] = target_shape[2] // num_splits
+
+            decoded_tiles = [
+                (
+                    self._hw_tiled_decode(z_tile, target_shape_split)
+                    if self.use_hw_tiling
+                    else self._decode(z_tile, target_shape=target_shape_split)
+                )
+                for z_tile in torch.tensor_split(z, num_splits, dim=2)
+            ]
+            decoded = torch.cat(decoded_tiles, dim=2)
+        else:
+            decoded = (
+                self._hw_tiled_decode(z, target_shape)
+                if self.use_hw_tiling
+                else self._decode(z, target_shape=target_shape, timestep=timestep)
+            )
+
+        if not return_dict:
+            return (decoded,)
+
+        return DecoderOutput(sample=decoded)
+
+    def forward(
+        self,
+        sample: torch.FloatTensor,
+        sample_posterior: bool = False,
+        return_dict: bool = True,
+        generator: Optional[torch.Generator] = None,
+    ) -> Union[DecoderOutput, torch.FloatTensor]:
+        r"""
+        Args:
+            sample (`torch.FloatTensor`): Input sample.
+            sample_posterior (`bool`, *optional*, defaults to `False`):
+                Whether to sample from the posterior.
+            return_dict (`bool`, *optional*, defaults to `True`):
+                Whether to return a [`DecoderOutput`] instead of a plain tuple.
+            generator (`torch.Generator`, *optional*):
+                Generator used to sample from the posterior.
+        """
+        x = sample
+        posterior = self.encode(x).latent_dist
+        if sample_posterior:
+            z = posterior.sample(generator=generator)
+        else:
+            z = posterior.mode()
+        dec = self.decode(z, target_shape=sample.shape).sample
+
+        if not return_dict:
+            return (dec,)
+
+        return DecoderOutput(sample=dec)

ltx_video/models/autoencoders/vae_encode.py

@@ -0,0 +1,247 @@
+from typing import Tuple
+import torch
+from diffusers import AutoencoderKL
+from einops import rearrange
+from torch import Tensor
+
+
+from ltx_video.models.autoencoders.causal_video_autoencoder import (
+    CausalVideoAutoencoder,
+)
+from ltx_video.models.autoencoders.video_autoencoder import (
+    Downsample3D,
+    VideoAutoencoder,
+)
+
+try:
+    import torch_xla.core.xla_model as xm
+except ImportError:
+    xm = None
+
+
+def vae_encode(
+    media_items: Tensor,
+    vae: AutoencoderKL,
+    split_size: int = 1,
+    vae_per_channel_normalize=False,
+) -> Tensor:
+    """
+    Encodes media items (images or videos) into latent representations using a specified VAE model.
+    The function supports processing batches of images or video frames and can handle the processing
+    in smaller sub-batches if needed.
+
+    Args:
+        media_items (Tensor): A torch Tensor containing the media items to encode. The expected
+            shape is (batch_size, channels, height, width) for images or (batch_size, channels,
+            frames, height, width) for videos.
+        vae (AutoencoderKL): An instance of the `AutoencoderKL` class from the `diffusers` library,
+            pre-configured and loaded with the appropriate model weights.
+        split_size (int, optional): The number of sub-batches to split the input batch into for encoding.
+            If set to more than 1, the input media items are processed in smaller batches according to
+            this value. Defaults to 1, which processes all items in a single batch.
+
+    Returns:
+        Tensor: A torch Tensor of the encoded latent representations. The shape of the tensor is adjusted
+            to match the input shape, scaled by the model's configuration.
+
+    Examples:
+        >>> import torch
+        >>> from diffusers import AutoencoderKL
+        >>> vae = AutoencoderKL.from_pretrained('your-model-name')
+        >>> images = torch.rand(10, 3, 8 256, 256)  # Example tensor with 10 videos of 8 frames.
+        >>> latents = vae_encode(images, vae)
+        >>> print(latents.shape)  # Output shape will depend on the model's latent configuration.
+
+    Note:
+        In case of a video, the function encodes the media item frame-by frame.
+    """
+    is_video_shaped = media_items.dim() == 5
+    batch_size, channels = media_items.shape[0:2]
+
+    if channels != 3:
+        raise ValueError(f"Expects tensors with 3 channels, got {channels}.")
+
+    if is_video_shaped and not isinstance(
+        vae, (VideoAutoencoder, CausalVideoAutoencoder)
+    ):
+        media_items = rearrange(media_items, "b c n h w -> (b n) c h w")
+    if split_size > 1:
+        if len(media_items) % split_size != 0:
+            raise ValueError(
+                "Error: The batch size must be divisible by 'train.vae_bs_split"
+            )
+        encode_bs = len(media_items) // split_size
+        # latents = [vae.encode(image_batch).latent_dist.sample() for image_batch in media_items.split(encode_bs)]
+        latents = []
+        if media_items.device.type == "xla":
+            xm.mark_step()
+        for image_batch in media_items.split(encode_bs):
+            latents.append(vae.encode(image_batch).latent_dist.sample())
+            if media_items.device.type == "xla":
+                xm.mark_step()
+        latents = torch.cat(latents, dim=0)
+    else:
+        latents = vae.encode(media_items).latent_dist.sample()
+
+    latents = normalize_latents(latents, vae, vae_per_channel_normalize)
+    if is_video_shaped and not isinstance(
+        vae, (VideoAutoencoder, CausalVideoAutoencoder)
+    ):
+        latents = rearrange(latents, "(b n) c h w -> b c n h w", b=batch_size)
+    return latents
+
+
+def vae_decode(
+    latents: Tensor,
+    vae: AutoencoderKL,
+    is_video: bool = True,
+    split_size: int = 1,
+    vae_per_channel_normalize=False,
+    timestep=None,
+) -> Tensor:
+    is_video_shaped = latents.dim() == 5
+    batch_size = latents.shape[0]
+
+    if is_video_shaped and not isinstance(
+        vae, (VideoAutoencoder, CausalVideoAutoencoder)
+    ):
+        latents = rearrange(latents, "b c n h w -> (b n) c h w")
+    if split_size > 1:
+        if len(latents) % split_size != 0:
+            raise ValueError(
+                "Error: The batch size must be divisible by 'train.vae_bs_split"
+            )
+        encode_bs = len(latents) // split_size
+        image_batch = [
+            _run_decoder(
+                latent_batch, vae, is_video, vae_per_channel_normalize, timestep
+            )
+            for latent_batch in latents.split(encode_bs)
+        ]
+        images = torch.cat(image_batch, dim=0)
+    else:
+        images = _run_decoder(
+            latents, vae, is_video, vae_per_channel_normalize, timestep
+        )
+
+    if is_video_shaped and not isinstance(
+        vae, (VideoAutoencoder, CausalVideoAutoencoder)
+    ):
+        images = rearrange(images, "(b n) c h w -> b c n h w", b=batch_size)
+    return images
+
+
+def _run_decoder(
+    latents: Tensor,
+    vae: AutoencoderKL,
+    is_video: bool,
+    vae_per_channel_normalize=False,
+    timestep=None,
+) -> Tensor:
+    if isinstance(vae, (VideoAutoencoder, CausalVideoAutoencoder)):
+        *_, fl, hl, wl = latents.shape
+        temporal_scale, spatial_scale, _ = get_vae_size_scale_factor(vae)
+        latents = latents.to(vae.dtype)
+        vae_decode_kwargs = {}
+        if timestep is not None:
+            vae_decode_kwargs["timestep"] = timestep
+        image = vae.decode(
+            un_normalize_latents(latents, vae, vae_per_channel_normalize),
+            return_dict=False,
+            target_shape=(
+                1,
+                3,
+                fl * temporal_scale if is_video else 1,
+                hl * spatial_scale,
+                wl * spatial_scale,
+            ),
+            **vae_decode_kwargs,
+        )[0]
+    else:
+        image = vae.decode(
+            un_normalize_latents(latents, vae, vae_per_channel_normalize),
+            return_dict=False,
+        )[0]
+    return image
+
+
+def get_vae_size_scale_factor(vae: AutoencoderKL) -> float:
+    if isinstance(vae, CausalVideoAutoencoder):
+        spatial = vae.spatial_downscale_factor
+        temporal = vae.temporal_downscale_factor
+    else:
+        down_blocks = len(
+            [
+                block
+                for block in vae.encoder.down_blocks
+                if isinstance(block.downsample, Downsample3D)
+            ]
+        )
+        spatial = vae.config.patch_size * 2**down_blocks
+        temporal = (
+            vae.config.patch_size_t * 2**down_blocks
+            if isinstance(vae, VideoAutoencoder)
+            else 1
+        )
+
+    return (temporal, spatial, spatial)
+
+
+def latent_to_pixel_coords(
+    latent_coords: Tensor, vae: AutoencoderKL, causal_fix: bool = False
+) -> Tensor:
+    """
+    Converts latent coordinates to pixel coordinates by scaling them according to the VAE's
+    configuration.
+
+    Args:
+        latent_coords (Tensor): A tensor of shape [batch_size, 3, num_latents]
+        containing the latent corner coordinates of each token.
+        vae (AutoencoderKL): The VAE model
+        causal_fix (bool): Whether to take into account the different temporal scale
+            of the first frame. Default = False for backwards compatibility.
+    Returns:
+        Tensor: A tensor of pixel coordinates corresponding to the input latent coordinates.
+    """
+
+    scale_factors = get_vae_size_scale_factor(vae)
+    causal_fix = isinstance(vae, CausalVideoAutoencoder) and causal_fix
+    pixel_coords = latent_to_pixel_coords_from_factors(
+        latent_coords, scale_factors, causal_fix
+    )
+    return pixel_coords
+
+
+def latent_to_pixel_coords_from_factors(
+    latent_coords: Tensor, scale_factors: Tuple, causal_fix: bool = False
+) -> Tensor:
+    pixel_coords = (
+        latent_coords
+        * torch.tensor(scale_factors, device=latent_coords.device)[None, :, None]
+    )
+    if causal_fix:
+        # Fix temporal scale for first frame to 1 due to causality
+        pixel_coords[:, 0] = (pixel_coords[:, 0] + 1 - scale_factors[0]).clamp(min=0)
+    return pixel_coords
+
+
+def normalize_latents(
+    latents: Tensor, vae: AutoencoderKL, vae_per_channel_normalize: bool = False
+) -> Tensor:
+    return (
+        (latents - vae.mean_of_means.to(latents.dtype).view(1, -1, 1, 1, 1))
+        / vae.std_of_means.to(latents.dtype).view(1, -1, 1, 1, 1)
+        if vae_per_channel_normalize
+        else latents * vae.config.scaling_factor
+    )
+
+
+def un_normalize_latents(
+    latents: Tensor, vae: AutoencoderKL, vae_per_channel_normalize: bool = False
+) -> Tensor:
+    return (
+        latents * vae.std_of_means.to(latents.dtype).view(1, -1, 1, 1, 1)
+        + vae.mean_of_means.to(latents.dtype).view(1, -1, 1, 1, 1)
+        if vae_per_channel_normalize
+        else latents / vae.config.scaling_factor
+    )

ltx_video/models/autoencoders/video_autoencoder.py

@@ -0,0 +1,1045 @@
+import json
+import os
+from functools import partial
+from types import SimpleNamespace
+from typing import Any, Mapping, Optional, Tuple, Union
+
+import torch
+from einops import rearrange
+from torch import nn
+from torch.nn import functional
+
+from diffusers.utils import logging
+
+from ltx_video.utils.torch_utils import Identity
+from ltx_video.models.autoencoders.conv_nd_factory import make_conv_nd, make_linear_nd
+from ltx_video.models.autoencoders.pixel_norm import PixelNorm
+from ltx_video.models.autoencoders.vae import AutoencoderKLWrapper
+
+logger = logging.get_logger(__name__)
+
+
+class VideoAutoencoder(AutoencoderKLWrapper):
+    @classmethod
+    def from_pretrained(
+        cls,
+        pretrained_model_name_or_path: Optional[Union[str, os.PathLike]],
+        *args,
+        **kwargs,
+    ):
+        config_local_path = pretrained_model_name_or_path / "config.json"
+        config = cls.load_config(config_local_path, **kwargs)
+        video_vae = cls.from_config(config)
+        video_vae.to(kwargs["torch_dtype"])
+
+        model_local_path = pretrained_model_name_or_path / "autoencoder.pth"
+        ckpt_state_dict = torch.load(model_local_path)
+        video_vae.load_state_dict(ckpt_state_dict)
+
+        statistics_local_path = (
+            pretrained_model_name_or_path / "per_channel_statistics.json"
+        )
+        if statistics_local_path.exists():
+            with open(statistics_local_path, "r") as file:
+                data = json.load(file)
+            transposed_data = list(zip(*data["data"]))
+            data_dict = {
+                col: torch.tensor(vals)
+                for col, vals in zip(data["columns"], transposed_data)
+            }
+            video_vae.register_buffer("std_of_means", data_dict["std-of-means"])
+            video_vae.register_buffer(
+                "mean_of_means",
+                data_dict.get(
+                    "mean-of-means", torch.zeros_like(data_dict["std-of-means"])
+                ),
+            )
+
+        return video_vae
+
+    @staticmethod
+    def from_config(config):
+        assert (
+            config["_class_name"] == "VideoAutoencoder"
+        ), "config must have _class_name=VideoAutoencoder"
+        if isinstance(config["dims"], list):
+            config["dims"] = tuple(config["dims"])
+
+        assert config["dims"] in [2, 3, (2, 1)], "dims must be 2, 3 or (2, 1)"
+
+        double_z = config.get("double_z", True)
+        latent_log_var = config.get(
+            "latent_log_var", "per_channel" if double_z else "none"
+        )
+        use_quant_conv = config.get("use_quant_conv", True)
+
+        if use_quant_conv and latent_log_var == "uniform":
+            raise ValueError("uniform latent_log_var requires use_quant_conv=False")
+
+        encoder = Encoder(
+            dims=config["dims"],
+            in_channels=config.get("in_channels", 3),
+            out_channels=config["latent_channels"],
+            block_out_channels=config["block_out_channels"],
+            patch_size=config.get("patch_size", 1),
+            latent_log_var=latent_log_var,
+            norm_layer=config.get("norm_layer", "group_norm"),
+            patch_size_t=config.get("patch_size_t", config.get("patch_size", 1)),
+            add_channel_padding=config.get("add_channel_padding", False),
+        )
+
+        decoder = Decoder(
+            dims=config["dims"],
+            in_channels=config["latent_channels"],
+            out_channels=config.get("out_channels", 3),
+            block_out_channels=config["block_out_channels"],
+            patch_size=config.get("patch_size", 1),
+            norm_layer=config.get("norm_layer", "group_norm"),
+            patch_size_t=config.get("patch_size_t", config.get("patch_size", 1)),
+            add_channel_padding=config.get("add_channel_padding", False),
+        )
+
+        dims = config["dims"]
+        return VideoAutoencoder(
+            encoder=encoder,
+            decoder=decoder,
+            latent_channels=config["latent_channels"],
+            dims=dims,
+            use_quant_conv=use_quant_conv,
+        )
+
+    @property
+    def config(self):
+        return SimpleNamespace(
+            _class_name="VideoAutoencoder",
+            dims=self.dims,
+            in_channels=self.encoder.conv_in.in_channels
+            // (self.encoder.patch_size_t * self.encoder.patch_size**2),
+            out_channels=self.decoder.conv_out.out_channels
+            // (self.decoder.patch_size_t * self.decoder.patch_size**2),
+            latent_channels=self.decoder.conv_in.in_channels,
+            block_out_channels=[
+                self.encoder.down_blocks[i].res_blocks[-1].conv1.out_channels
+                for i in range(len(self.encoder.down_blocks))
+            ],
+            scaling_factor=1.0,
+            norm_layer=self.encoder.norm_layer,
+            patch_size=self.encoder.patch_size,
+            latent_log_var=self.encoder.latent_log_var,
+            use_quant_conv=self.use_quant_conv,
+            patch_size_t=self.encoder.patch_size_t,
+            add_channel_padding=self.encoder.add_channel_padding,
+        )
+
+    @property
+    def is_video_supported(self):
+        """
+        Check if the model supports video inputs of shape (B, C, F, H, W). Otherwise, the model only supports 2D images.
+        """
+        return self.dims != 2
+
+    @property
+    def downscale_factor(self):
+        return self.encoder.downsample_factor
+
+    def to_json_string(self) -> str:
+        import json
+
+        return json.dumps(self.config.__dict__)
+
+    def load_state_dict(self, state_dict: Mapping[str, Any], strict: bool = True):
+        model_keys = set(name for name, _ in self.named_parameters())
+
+        key_mapping = {
+            ".resnets.": ".res_blocks.",
+            "downsamplers.0": "downsample",
+            "upsamplers.0": "upsample",
+        }
+
+        converted_state_dict = {}
+        for key, value in state_dict.items():
+            for k, v in key_mapping.items():
+                key = key.replace(k, v)
+
+            if "norm" in key and key not in model_keys:
+                logger.info(
+                    f"Removing key {key} from state_dict as it is not present in the model"
+                )
+                continue
+
+            converted_state_dict[key] = value
+
+        super().load_state_dict(converted_state_dict, strict=strict)
+
+    def last_layer(self):
+        if hasattr(self.decoder, "conv_out"):
+            if isinstance(self.decoder.conv_out, nn.Sequential):
+                last_layer = self.decoder.conv_out[-1]
+            else:
+                last_layer = self.decoder.conv_out
+        else:
+            last_layer = self.decoder.layers[-1]
+        return last_layer
+
+
+class Encoder(nn.Module):
+    r"""
+    The `Encoder` layer of a variational autoencoder that encodes its input into a latent representation.
+
+    Args:
+        in_channels (`int`, *optional*, defaults to 3):
+            The number of input channels.
+        out_channels (`int`, *optional*, defaults to 3):
+            The number of output channels.
+        block_out_channels (`Tuple[int, ...]`, *optional*, defaults to `(64,)`):
+            The number of output channels for each block.
+        layers_per_block (`int`, *optional*, defaults to 2):
+            The number of layers per block.
+        norm_num_groups (`int`, *optional*, defaults to 32):
+            The number of groups for normalization.
+        patch_size (`int`, *optional*, defaults to 1):
+            The patch size to use. Should be a power of 2.
+        norm_layer (`str`, *optional*, defaults to `group_norm`):
+            The normalization layer to use. Can be either `group_norm` or `pixel_norm`.
+        latent_log_var (`str`, *optional*, defaults to `per_channel`):
+            The number of channels for the log variance. Can be either `per_channel`, `uniform`, or `none`.
+    """
+
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]] = 3,
+        in_channels: int = 3,
+        out_channels: int = 3,
+        block_out_channels: Tuple[int, ...] = (64,),
+        layers_per_block: int = 2,
+        norm_num_groups: int = 32,
+        patch_size: Union[int, Tuple[int]] = 1,
+        norm_layer: str = "group_norm",  # group_norm, pixel_norm
+        latent_log_var: str = "per_channel",
+        patch_size_t: Optional[int] = None,
+        add_channel_padding: Optional[bool] = False,
+    ):
+        super().__init__()
+        self.patch_size = patch_size
+        self.patch_size_t = patch_size_t if patch_size_t is not None else patch_size
+        self.add_channel_padding = add_channel_padding
+        self.layers_per_block = layers_per_block
+        self.norm_layer = norm_layer
+        self.latent_channels = out_channels
+        self.latent_log_var = latent_log_var
+        if add_channel_padding:
+            in_channels = in_channels * self.patch_size**3
+        else:
+            in_channels = in_channels * self.patch_size_t * self.patch_size**2
+        self.in_channels = in_channels
+        output_channel = block_out_channels[0]
+
+        self.conv_in = make_conv_nd(
+            dims=dims,
+            in_channels=in_channels,
+            out_channels=output_channel,
+            kernel_size=3,
+            stride=1,
+            padding=1,
+        )
+
+        self.down_blocks = nn.ModuleList([])
+
+        for i in range(len(block_out_channels)):
+            input_channel = output_channel
+            output_channel = block_out_channels[i]
+            is_final_block = i == len(block_out_channels) - 1
+
+            down_block = DownEncoderBlock3D(
+                dims=dims,
+                in_channels=input_channel,
+                out_channels=output_channel,
+                num_layers=self.layers_per_block,
+                add_downsample=not is_final_block and 2**i >= patch_size,
+                resnet_eps=1e-6,
+                downsample_padding=0,
+                resnet_groups=norm_num_groups,
+                norm_layer=norm_layer,
+            )
+            self.down_blocks.append(down_block)
+
+        self.mid_block = UNetMidBlock3D(
+            dims=dims,
+            in_channels=block_out_channels[-1],
+            num_layers=self.layers_per_block,
+            resnet_eps=1e-6,
+            resnet_groups=norm_num_groups,
+            norm_layer=norm_layer,
+        )
+
+        # out
+        if norm_layer == "group_norm":
+            self.conv_norm_out = nn.GroupNorm(
+                num_channels=block_out_channels[-1],
+                num_groups=norm_num_groups,
+                eps=1e-6,
+            )
+        elif norm_layer == "pixel_norm":
+            self.conv_norm_out = PixelNorm()
+        self.conv_act = nn.SiLU()
+
+        conv_out_channels = out_channels
+        if latent_log_var == "per_channel":
+            conv_out_channels *= 2
+        elif latent_log_var == "uniform":
+            conv_out_channels += 1
+        elif latent_log_var != "none":
+            raise ValueError(f"Invalid latent_log_var: {latent_log_var}")
+        self.conv_out = make_conv_nd(
+            dims, block_out_channels[-1], conv_out_channels, 3, padding=1
+        )
+
+        self.gradient_checkpointing = False
+
+    @property
+    def downscale_factor(self):
+        return (
+            2
+            ** len(
+                [
+                    block
+                    for block in self.down_blocks
+                    if isinstance(block.downsample, Downsample3D)
+                ]
+            )
+            * self.patch_size
+        )
+
+    def forward(
+        self, sample: torch.FloatTensor, return_features=False
+    ) -> torch.FloatTensor:
+        r"""The forward method of the `Encoder` class."""
+
+        downsample_in_time = sample.shape[2] != 1
+
+        # patchify
+        patch_size_t = self.patch_size_t if downsample_in_time else 1
+        sample = patchify(
+            sample,
+            patch_size_hw=self.patch_size,
+            patch_size_t=patch_size_t,
+            add_channel_padding=self.add_channel_padding,
+        )
+
+        sample = self.conv_in(sample)
+
+        checkpoint_fn = (
+            partial(torch.utils.checkpoint.checkpoint, use_reentrant=False)
+            if self.gradient_checkpointing and self.training
+            else lambda x: x
+        )
+
+        if return_features:
+            features = []
+        for down_block in self.down_blocks:
+            sample = checkpoint_fn(down_block)(
+                sample, downsample_in_time=downsample_in_time
+            )
+            if return_features:
+                features.append(sample)
+
+        sample = checkpoint_fn(self.mid_block)(sample)
+
+        # post-process
+        sample = self.conv_norm_out(sample)
+        sample = self.conv_act(sample)
+        sample = self.conv_out(sample)
+
+        if self.latent_log_var == "uniform":
+            last_channel = sample[:, -1:, ...]
+            num_dims = sample.dim()
+
+            if num_dims == 4:
+                # For shape (B, C, H, W)
+                repeated_last_channel = last_channel.repeat(
+                    1, sample.shape[1] - 2, 1, 1
+                )
+                sample = torch.cat([sample, repeated_last_channel], dim=1)
+            elif num_dims == 5:
+                # For shape (B, C, F, H, W)
+                repeated_last_channel = last_channel.repeat(
+                    1, sample.shape[1] - 2, 1, 1, 1
+                )
+                sample = torch.cat([sample, repeated_last_channel], dim=1)
+            else:
+                raise ValueError(f"Invalid input shape: {sample.shape}")
+
+        if return_features:
+            features.append(sample[:, : self.latent_channels, ...])
+            return sample, features
+        return sample
+
+
+class Decoder(nn.Module):
+    r"""
+    The `Decoder` layer of a variational autoencoder that decodes its latent representation into an output sample.
+
+    Args:
+        in_channels (`int`, *optional*, defaults to 3):
+            The number of input channels.
+        out_channels (`int`, *optional*, defaults to 3):
+            The number of output channels.
+        block_out_channels (`Tuple[int, ...]`, *optional*, defaults to `(64,)`):
+            The number of output channels for each block.
+        layers_per_block (`int`, *optional*, defaults to 2):
+            The number of layers per block.
+        norm_num_groups (`int`, *optional*, defaults to 32):
+            The number of groups for normalization.
+        patch_size (`int`, *optional*, defaults to 1):
+            The patch size to use. Should be a power of 2.
+        norm_layer (`str`, *optional*, defaults to `group_norm`):
+            The normalization layer to use. Can be either `group_norm` or `pixel_norm`.
+    """
+
+    def __init__(
+        self,
+        dims,
+        in_channels: int = 3,
+        out_channels: int = 3,
+        block_out_channels: Tuple[int, ...] = (64,),
+        layers_per_block: int = 2,
+        norm_num_groups: int = 32,
+        patch_size: int = 1,
+        norm_layer: str = "group_norm",
+        patch_size_t: Optional[int] = None,
+        add_channel_padding: Optional[bool] = False,
+    ):
+        super().__init__()
+        self.patch_size = patch_size
+        self.patch_size_t = patch_size_t if patch_size_t is not None else patch_size
+        self.add_channel_padding = add_channel_padding
+        self.layers_per_block = layers_per_block
+        if add_channel_padding:
+            out_channels = out_channels * self.patch_size**3
+        else:
+            out_channels = out_channels * self.patch_size_t * self.patch_size**2
+        self.out_channels = out_channels
+
+        self.conv_in = make_conv_nd(
+            dims,
+            in_channels,
+            block_out_channels[-1],
+            kernel_size=3,
+            stride=1,
+            padding=1,
+        )
+
+        self.mid_block = None
+        self.up_blocks = nn.ModuleList([])
+
+        self.mid_block = UNetMidBlock3D(
+            dims=dims,
+            in_channels=block_out_channels[-1],
+            num_layers=self.layers_per_block,
+            resnet_eps=1e-6,
+            resnet_groups=norm_num_groups,
+            norm_layer=norm_layer,
+        )
+
+        reversed_block_out_channels = list(reversed(block_out_channels))
+        output_channel = reversed_block_out_channels[0]
+        for i in range(len(reversed_block_out_channels)):
+            prev_output_channel = output_channel
+            output_channel = reversed_block_out_channels[i]
+
+            is_final_block = i == len(block_out_channels) - 1
+
+            up_block = UpDecoderBlock3D(
+                dims=dims,
+                num_layers=self.layers_per_block + 1,
+                in_channels=prev_output_channel,
+                out_channels=output_channel,
+                add_upsample=not is_final_block
+                and 2 ** (len(block_out_channels) - i - 1) > patch_size,
+                resnet_eps=1e-6,
+                resnet_groups=norm_num_groups,
+                norm_layer=norm_layer,
+            )
+            self.up_blocks.append(up_block)
+
+        if norm_layer == "group_norm":
+            self.conv_norm_out = nn.GroupNorm(
+                num_channels=block_out_channels[0], num_groups=norm_num_groups, eps=1e-6
+            )
+        elif norm_layer == "pixel_norm":
+            self.conv_norm_out = PixelNorm()
+
+        self.conv_act = nn.SiLU()
+        self.conv_out = make_conv_nd(
+            dims, block_out_channels[0], out_channels, 3, padding=1
+        )
+
+        self.gradient_checkpointing = False
+
+    def forward(self, sample: torch.FloatTensor, target_shape) -> torch.FloatTensor:
+        r"""The forward method of the `Decoder` class."""
+        assert target_shape is not None, "target_shape must be provided"
+        upsample_in_time = sample.shape[2] < target_shape[2]
+
+        sample = self.conv_in(sample)
+
+        upscale_dtype = next(iter(self.up_blocks.parameters())).dtype
+
+        checkpoint_fn = (
+            partial(torch.utils.checkpoint.checkpoint, use_reentrant=False)
+            if self.gradient_checkpointing and self.training
+            else lambda x: x
+        )
+
+        sample = checkpoint_fn(self.mid_block)(sample)
+        sample = sample.to(upscale_dtype)
+
+        for up_block in self.up_blocks:
+            sample = checkpoint_fn(up_block)(sample, upsample_in_time=upsample_in_time)
+
+        # post-process
+        sample = self.conv_norm_out(sample)
+        sample = self.conv_act(sample)
+        sample = self.conv_out(sample)
+
+        # un-patchify
+        patch_size_t = self.patch_size_t if upsample_in_time else 1
+        sample = unpatchify(
+            sample,
+            patch_size_hw=self.patch_size,
+            patch_size_t=patch_size_t,
+            add_channel_padding=self.add_channel_padding,
+        )
+
+        return sample
+
+
+class DownEncoderBlock3D(nn.Module):
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]],
+        in_channels: int,
+        out_channels: int,
+        dropout: float = 0.0,
+        num_layers: int = 1,
+        resnet_eps: float = 1e-6,
+        resnet_groups: int = 32,
+        add_downsample: bool = True,
+        downsample_padding: int = 1,
+        norm_layer: str = "group_norm",
+    ):
+        super().__init__()
+        res_blocks = []
+
+        for i in range(num_layers):
+            in_channels = in_channels if i == 0 else out_channels
+            res_blocks.append(
+                ResnetBlock3D(
+                    dims=dims,
+                    in_channels=in_channels,
+                    out_channels=out_channels,
+                    eps=resnet_eps,
+                    groups=resnet_groups,
+                    dropout=dropout,
+                    norm_layer=norm_layer,
+                )
+            )
+
+        self.res_blocks = nn.ModuleList(res_blocks)
+
+        if add_downsample:
+            self.downsample = Downsample3D(
+                dims,
+                out_channels,
+                out_channels=out_channels,
+                padding=downsample_padding,
+            )
+        else:
+            self.downsample = Identity()
+
+    def forward(
+        self, hidden_states: torch.FloatTensor, downsample_in_time
+    ) -> torch.FloatTensor:
+        for resnet in self.res_blocks:
+            hidden_states = resnet(hidden_states)
+
+        hidden_states = self.downsample(
+            hidden_states, downsample_in_time=downsample_in_time
+        )
+
+        return hidden_states
+
+
+class UNetMidBlock3D(nn.Module):
+    """
+    A 3D UNet mid-block [`UNetMidBlock3D`] with multiple residual blocks.
+
+    Args:
+        in_channels (`int`): The number of input channels.
+        dropout (`float`, *optional*, defaults to 0.0): The dropout rate.
+        num_layers (`int`, *optional*, defaults to 1): The number of residual blocks.
+        resnet_eps (`float`, *optional*, 1e-6 ): The epsilon value for the resnet blocks.
+        resnet_groups (`int`, *optional*, defaults to 32):
+            The number of groups to use in the group normalization layers of the resnet blocks.
+
+    Returns:
+        `torch.FloatTensor`: The output of the last residual block, which is a tensor of shape `(batch_size,
+        in_channels, height, width)`.
+
+    """
+
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]],
+        in_channels: int,
+        dropout: float = 0.0,
+        num_layers: int = 1,
+        resnet_eps: float = 1e-6,
+        resnet_groups: int = 32,
+        norm_layer: str = "group_norm",
+    ):
+        super().__init__()
+        resnet_groups = (
+            resnet_groups if resnet_groups is not None else min(in_channels // 4, 32)
+        )
+
+        self.res_blocks = nn.ModuleList(
+            [
+                ResnetBlock3D(
+                    dims=dims,
+                    in_channels=in_channels,
+                    out_channels=in_channels,
+                    eps=resnet_eps,
+                    groups=resnet_groups,
+                    dropout=dropout,
+                    norm_layer=norm_layer,
+                )
+                for _ in range(num_layers)
+            ]
+        )
+
+    def forward(self, hidden_states: torch.FloatTensor) -> torch.FloatTensor:
+        for resnet in self.res_blocks:
+            hidden_states = resnet(hidden_states)
+
+        return hidden_states
+
+
+class UpDecoderBlock3D(nn.Module):
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]],
+        in_channels: int,
+        out_channels: int,
+        resolution_idx: Optional[int] = None,
+        dropout: float = 0.0,
+        num_layers: int = 1,
+        resnet_eps: float = 1e-6,
+        resnet_groups: int = 32,
+        add_upsample: bool = True,
+        norm_layer: str = "group_norm",
+    ):
+        super().__init__()
+        res_blocks = []
+
+        for i in range(num_layers):
+            input_channels = in_channels if i == 0 else out_channels
+
+            res_blocks.append(
+                ResnetBlock3D(
+                    dims=dims,
+                    in_channels=input_channels,
+                    out_channels=out_channels,
+                    eps=resnet_eps,
+                    groups=resnet_groups,
+                    dropout=dropout,
+                    norm_layer=norm_layer,
+                )
+            )
+
+        self.res_blocks = nn.ModuleList(res_blocks)
+
+        if add_upsample:
+            self.upsample = Upsample3D(
+                dims=dims, channels=out_channels, out_channels=out_channels
+            )
+        else:
+            self.upsample = Identity()
+
+        self.resolution_idx = resolution_idx
+
+    def forward(
+        self, hidden_states: torch.FloatTensor, upsample_in_time=True
+    ) -> torch.FloatTensor:
+        for resnet in self.res_blocks:
+            hidden_states = resnet(hidden_states)
+
+        hidden_states = self.upsample(hidden_states, upsample_in_time=upsample_in_time)
+
+        return hidden_states
+
+
+class ResnetBlock3D(nn.Module):
+    r"""
+    A Resnet block.
+
+    Parameters:
+        in_channels (`int`): The number of channels in the input.
+        out_channels (`int`, *optional*, default to be `None`):
+            The number of output channels for the first conv layer. If None, same as `in_channels`.
+        dropout (`float`, *optional*, defaults to `0.0`): The dropout probability to use.
+        groups (`int`, *optional*, default to `32`): The number of groups to use for the first normalization layer.
+        eps (`float`, *optional*, defaults to `1e-6`): The epsilon to use for the normalization.
+    """
+
+    def __init__(
+        self,
+        dims: Union[int, Tuple[int, int]],
+        in_channels: int,
+        out_channels: Optional[int] = None,
+        conv_shortcut: bool = False,
+        dropout: float = 0.0,
+        groups: int = 32,
+        eps: float = 1e-6,
+        norm_layer: str = "group_norm",
+    ):
+        super().__init__()
+        self.in_channels = in_channels
+        out_channels = in_channels if out_channels is None else out_channels
+        self.out_channels = out_channels
+        self.use_conv_shortcut = conv_shortcut
+
+        if norm_layer == "group_norm":
+            self.norm1 = torch.nn.GroupNorm(
+                num_groups=groups, num_channels=in_channels, eps=eps, affine=True
+            )
+        elif norm_layer == "pixel_norm":
+            self.norm1 = PixelNorm()
+
+        self.non_linearity = nn.SiLU()
+
+        self.conv1 = make_conv_nd(
+            dims, in_channels, out_channels, kernel_size=3, stride=1, padding=1
+        )
+
+        if norm_layer == "group_norm":
+            self.norm2 = torch.nn.GroupNorm(
+                num_groups=groups, num_channels=out_channels, eps=eps, affine=True
+            )
+        elif norm_layer == "pixel_norm":
+            self.norm2 = PixelNorm()
+
+        self.dropout = torch.nn.Dropout(dropout)
+
+        self.conv2 = make_conv_nd(
+            dims, out_channels, out_channels, kernel_size=3, stride=1, padding=1
+        )
+
+        self.conv_shortcut = (
+            make_linear_nd(
+                dims=dims, in_channels=in_channels, out_channels=out_channels
+            )
+            if in_channels != out_channels
+            else nn.Identity()
+        )
+
+    def forward(
+        self,
+        input_tensor: torch.FloatTensor,
+    ) -> torch.FloatTensor:
+        hidden_states = input_tensor
+
+        hidden_states = self.norm1(hidden_states)
+
+        hidden_states = self.non_linearity(hidden_states)
+
+        hidden_states = self.conv1(hidden_states)
+
+        hidden_states = self.norm2(hidden_states)
+
+        hidden_states = self.non_linearity(hidden_states)
+
+        hidden_states = self.dropout(hidden_states)
+
+        hidden_states = self.conv2(hidden_states)
+
+        input_tensor = self.conv_shortcut(input_tensor)
+
+        output_tensor = input_tensor + hidden_states
+
+        return output_tensor
+
+
+class Downsample3D(nn.Module):
+    def __init__(
+        self,
+        dims,
+        in_channels: int,
+        out_channels: int,
+        kernel_size: int = 3,
+        padding: int = 1,
+    ):
+        super().__init__()
+        stride: int = 2
+        self.padding = padding
+        self.in_channels = in_channels
+        self.dims = dims
+        self.conv = make_conv_nd(
+            dims=dims,
+            in_channels=in_channels,
+            out_channels=out_channels,
+            kernel_size=kernel_size,
+            stride=stride,
+            padding=padding,
+        )
+
+    def forward(self, x, downsample_in_time=True):
+        conv = self.conv
+        if self.padding == 0:
+            if self.dims == 2:
+                padding = (0, 1, 0, 1)
+            else:
+                padding = (0, 1, 0, 1, 0, 1 if downsample_in_time else 0)
+
+            x = functional.pad(x, padding, mode="constant", value=0)
+
+            if self.dims == (2, 1) and not downsample_in_time:
+                return conv(x, skip_time_conv=True)
+
+        return conv(x)
+
+
+class Upsample3D(nn.Module):
+    """
+    An upsampling layer for 3D tensors of shape (B, C, D, H, W).
+
+    :param channels: channels in the inputs and outputs.
+    """
+
+    def __init__(self, dims, channels, out_channels=None):
+        super().__init__()
+        self.dims = dims
+        self.channels = channels
+        self.out_channels = out_channels or channels
+        self.conv = make_conv_nd(
+            dims, channels, out_channels, kernel_size=3, padding=1, bias=True
+        )
+
+    def forward(self, x, upsample_in_time):
+        if self.dims == 2:
+            x = functional.interpolate(
+                x, (x.shape[2] * 2, x.shape[3] * 2), mode="nearest"
+            )
+        else:
+            time_scale_factor = 2 if upsample_in_time else 1
+            # print("before:", x.shape)
+            b, c, d, h, w = x.shape
+            x = rearrange(x, "b c d h w -> (b d) c h w")
+            # height and width interpolate
+            x = functional.interpolate(
+                x, (x.shape[2] * 2, x.shape[3] * 2), mode="nearest"
+            )
+            _, _, h, w = x.shape
+
+            if not upsample_in_time and self.dims == (2, 1):
+                x = rearrange(x, "(b d) c h w -> b c d h w ", b=b, h=h, w=w)
+                return self.conv(x, skip_time_conv=True)
+
+            # Second ** upsampling ** which is essentially treated as a 1D convolution across the 'd' dimension
+            x = rearrange(x, "(b d) c h w -> (b h w) c 1 d", b=b)
+
+            # (b h w) c 1 d
+            new_d = x.shape[-1] * time_scale_factor
+            x = functional.interpolate(x, (1, new_d), mode="nearest")
+            # (b h w) c 1 new_d
+            x = rearrange(
+                x, "(b h w) c 1 new_d  -> b c new_d h w", b=b, h=h, w=w, new_d=new_d
+            )
+            # b c d h w
+
+            # x = functional.interpolate(
+            #     x, (x.shape[2] * time_scale_factor, x.shape[3] * 2, x.shape[4] * 2), mode="nearest"
+            # )
+            # print("after:", x.shape)
+
+        return self.conv(x)
+
+
+def patchify(x, patch_size_hw, patch_size_t=1, add_channel_padding=False):
+    if patch_size_hw == 1 and patch_size_t == 1:
+        return x
+    if x.dim() == 4:
+        x = rearrange(
+            x, "b c (h q) (w r) -> b (c r q) h w", q=patch_size_hw, r=patch_size_hw
+        )
+    elif x.dim() == 5:
+        x = rearrange(
+            x,
+            "b c (f p) (h q) (w r) -> b (c p r q) f h w",
+            p=patch_size_t,
+            q=patch_size_hw,
+            r=patch_size_hw,
+        )
+    else:
+        raise ValueError(f"Invalid input shape: {x.shape}")
+
+    if (
+        (x.dim() == 5)
+        and (patch_size_hw > patch_size_t)
+        and (patch_size_t > 1 or add_channel_padding)
+    ):
+        channels_to_pad = x.shape[1] * (patch_size_hw // patch_size_t) - x.shape[1]
+        padding_zeros = torch.zeros(
+            x.shape[0],
+            channels_to_pad,
+            x.shape[2],
+            x.shape[3],
+            x.shape[4],
+            device=x.device,
+            dtype=x.dtype,
+        )
+        x = torch.cat([padding_zeros, x], dim=1)
+
+    return x
+
+
+def unpatchify(x, patch_size_hw, patch_size_t=1, add_channel_padding=False):
+    if patch_size_hw == 1 and patch_size_t == 1:
+        return x
+
+    if (
+        (x.dim() == 5)
+        and (patch_size_hw > patch_size_t)
+        and (patch_size_t > 1 or add_channel_padding)
+    ):
+        channels_to_keep = int(x.shape[1] * (patch_size_t / patch_size_hw))
+        x = x[:, :channels_to_keep, :, :, :]
+
+    if x.dim() == 4:
+        x = rearrange(
+            x, "b (c r q) h w -> b c (h q) (w r)", q=patch_size_hw, r=patch_size_hw
+        )
+    elif x.dim() == 5:
+        x = rearrange(
+            x,
+            "b (c p r q) f h w -> b c (f p) (h q) (w r)",
+            p=patch_size_t,
+            q=patch_size_hw,
+            r=patch_size_hw,
+        )
+
+    return x
+
+
+def create_video_autoencoder_config(
+    latent_channels: int = 4,
+):
+    config = {
+        "_class_name": "VideoAutoencoder",
+        "dims": (
+            2,
+            1,
+        ),  # 2 for Conv2, 3 for Conv3d, (2, 1) for Conv2d followed by Conv1d
+        "in_channels": 3,  # Number of input color channels (e.g., RGB)
+        "out_channels": 3,  # Number of output color channels
+        "latent_channels": latent_channels,  # Number of channels in the latent space representation
+        "block_out_channels": [
+            128,
+            256,
+            512,
+            512,
+        ],  # Number of output channels of each encoder / decoder inner block
+        "patch_size": 1,
+    }
+
+    return config
+
+
+def create_video_autoencoder_pathify4x4x4_config(
+    latent_channels: int = 4,
+):
+    config = {
+        "_class_name": "VideoAutoencoder",
+        "dims": (
+            2,
+            1,
+        ),  # 2 for Conv2, 3 for Conv3d, (2, 1) for Conv2d followed by Conv1d
+        "in_channels": 3,  # Number of input color channels (e.g., RGB)
+        "out_channels": 3,  # Number of output color channels
+        "latent_channels": latent_channels,  # Number of channels in the latent space representation
+        "block_out_channels": [512]
+        * 4,  # Number of output channels of each encoder / decoder inner block
+        "patch_size": 4,
+        "latent_log_var": "uniform",
+    }
+
+    return config
+
+
+def create_video_autoencoder_pathify4x4_config(
+    latent_channels: int = 4,
+):
+    config = {
+        "_class_name": "VideoAutoencoder",
+        "dims": 2,  # 2 for Conv2, 3 for Conv3d, (2, 1) for Conv2d followed by Conv1d
+        "in_channels": 3,  # Number of input color channels (e.g., RGB)
+        "out_channels": 3,  # Number of output color channels
+        "latent_channels": latent_channels,  # Number of channels in the latent space representation
+        "block_out_channels": [512]
+        * 4,  # Number of output channels of each encoder / decoder inner block
+        "patch_size": 4,
+        "norm_layer": "pixel_norm",
+    }
+
+    return config
+
+
+def test_vae_patchify_unpatchify():
+    import torch
+
+    x = torch.randn(2, 3, 8, 64, 64)
+    x_patched = patchify(x, patch_size_hw=4, patch_size_t=4)
+    x_unpatched = unpatchify(x_patched, patch_size_hw=4, patch_size_t=4)
+    assert torch.allclose(x, x_unpatched)
+
+
+def demo_video_autoencoder_forward_backward():
+    # Configuration for the VideoAutoencoder
+    config = create_video_autoencoder_pathify4x4x4_config()
+
+    # Instantiate the VideoAutoencoder with the specified configuration
+    video_autoencoder = VideoAutoencoder.from_config(config)
+
+    print(video_autoencoder)
+
+    # Print the total number of parameters in the video autoencoder
+    total_params = sum(p.numel() for p in video_autoencoder.parameters())
+    print(f"Total number of parameters in VideoAutoencoder: {total_params:,}")
+
+    # Create a mock input tensor simulating a batch of videos
+    # Shape: (batch_size, channels, depth, height, width)
+    # E.g., 4 videos, each with 3 color channels, 16 frames, and 64x64 pixels per frame
+    input_videos = torch.randn(2, 3, 8, 64, 64)
+
+    # Forward pass: encode and decode the input videos
+    latent = video_autoencoder.encode(input_videos).latent_dist.mode()
+    print(f"input shape={input_videos.shape}")
+    print(f"latent shape={latent.shape}")
+    reconstructed_videos = video_autoencoder.decode(
+        latent, target_shape=input_videos.shape
+    ).sample
+
+    print(f"reconstructed shape={reconstructed_videos.shape}")
+
+    # Calculate the loss (e.g., mean squared error)
+    loss = torch.nn.functional.mse_loss(input_videos, reconstructed_videos)
+
+    # Perform backward pass
+    loss.backward()
+
+    print(f"Demo completed with loss: {loss.item()}")
+
+
+# Ensure to call the demo function to execute the forward and backward pass
+if __name__ == "__main__":
+    demo_video_autoencoder_forward_backward()

ltx_video/models/transformers/attention.py

@@ -0,0 +1,1265 @@
+import inspect
+from importlib import import_module
+from typing import Any, Dict, Optional, Tuple
+
+import torch
+import torch.nn.functional as F
+from diffusers.models.activations import GEGLU, GELU, ApproximateGELU
+from diffusers.models.attention import _chunked_feed_forward
+from diffusers.models.attention_processor import (
+    LoRAAttnAddedKVProcessor,
+    LoRAAttnProcessor,
+    LoRAAttnProcessor2_0,
+    LoRAXFormersAttnProcessor,
+    SpatialNorm,
+)
+from diffusers.models.lora import LoRACompatibleLinear
+from diffusers.models.normalization import RMSNorm
+from diffusers.utils import deprecate, logging
+from diffusers.utils.torch_utils import maybe_allow_in_graph
+from einops import rearrange
+from torch import nn
+
+from ltx_video.utils.skip_layer_strategy import SkipLayerStrategy
+
+try:
+    from torch_xla.experimental.custom_kernel import flash_attention
+except ImportError:
+    # workaround for automatic tests. Currently this function is manually patched
+    # to the torch_xla lib on setup of container
+    pass
+
+# code adapted from  https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention.py
+
+logger = logging.get_logger(__name__)
+
+
+@maybe_allow_in_graph
+class BasicTransformerBlock(nn.Module):
+    r"""
+    A basic Transformer block.
+
+    Parameters:
+        dim (`int`): The number of channels in the input and output.
+        num_attention_heads (`int`): The number of heads to use for multi-head attention.
+        attention_head_dim (`int`): The number of channels in each head.
+        dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
+        cross_attention_dim (`int`, *optional*): The size of the encoder_hidden_states vector for cross attention.
+        activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward.
+        num_embeds_ada_norm (:
+            obj: `int`, *optional*): The number of diffusion steps used during training. See `Transformer2DModel`.
+        attention_bias (:
+            obj: `bool`, *optional*, defaults to `False`): Configure if the attentions should contain a bias parameter.
+        only_cross_attention (`bool`, *optional*):
+            Whether to use only cross-attention layers. In this case two cross attention layers are used.
+        double_self_attention (`bool`, *optional*):
+            Whether to use two self-attention layers. In this case no cross attention layers are used.
+        upcast_attention (`bool`, *optional*):
+            Whether to upcast the attention computation to float32. This is useful for mixed precision training.
+        norm_elementwise_affine (`bool`, *optional*, defaults to `True`):
+            Whether to use learnable elementwise affine parameters for normalization.
+        qk_norm (`str`, *optional*, defaults to None):
+            Set to 'layer_norm' or `rms_norm` to perform query and key normalization.
+        adaptive_norm (`str`, *optional*, defaults to `"single_scale_shift"`):
+            The type of adaptive norm to use. Can be `"single_scale_shift"`, `"single_scale"` or "none".
+        standardization_norm (`str`, *optional*, defaults to `"layer_norm"`):
+            The type of pre-normalization to use. Can be `"layer_norm"` or `"rms_norm"`.
+        final_dropout (`bool` *optional*, defaults to False):
+            Whether to apply a final dropout after the last feed-forward layer.
+        attention_type (`str`, *optional*, defaults to `"default"`):
+            The type of attention to use. Can be `"default"` or `"gated"` or `"gated-text-image"`.
+        positional_embeddings (`str`, *optional*, defaults to `None`):
+            The type of positional embeddings to apply to.
+        num_positional_embeddings (`int`, *optional*, defaults to `None`):
+            The maximum number of positional embeddings to apply.
+    """
+
+    def __init__(
+        self,
+        dim: int,
+        num_attention_heads: int,
+        attention_head_dim: int,
+        dropout=0.0,
+        cross_attention_dim: Optional[int] = None,
+        activation_fn: str = "geglu",
+        num_embeds_ada_norm: Optional[int] = None,  # pylint: disable=unused-argument
+        attention_bias: bool = False,
+        only_cross_attention: bool = False,
+        double_self_attention: bool = False,
+        upcast_attention: bool = False,
+        norm_elementwise_affine: bool = True,
+        adaptive_norm: str = "single_scale_shift",  # 'single_scale_shift', 'single_scale' or 'none'
+        standardization_norm: str = "layer_norm",  # 'layer_norm' or 'rms_norm'
+        norm_eps: float = 1e-5,
+        qk_norm: Optional[str] = None,
+        final_dropout: bool = False,
+        attention_type: str = "default",  # pylint: disable=unused-argument
+        ff_inner_dim: Optional[int] = None,
+        ff_bias: bool = True,
+        attention_out_bias: bool = True,
+        use_tpu_flash_attention: bool = False,
+        use_rope: bool = False,
+    ):
+        super().__init__()
+        self.only_cross_attention = only_cross_attention
+        self.use_tpu_flash_attention = use_tpu_flash_attention
+        self.adaptive_norm = adaptive_norm
+
+        assert standardization_norm in ["layer_norm", "rms_norm"]
+        assert adaptive_norm in ["single_scale_shift", "single_scale", "none"]
+
+        make_norm_layer = (
+            nn.LayerNorm if standardization_norm == "layer_norm" else RMSNorm
+        )
+
+        # Define 3 blocks. Each block has its own normalization layer.
+        # 1. Self-Attn
+        self.norm1 = make_norm_layer(
+            dim, elementwise_affine=norm_elementwise_affine, eps=norm_eps
+        )
+
+        self.attn1 = Attention(
+            query_dim=dim,
+            heads=num_attention_heads,
+            dim_head=attention_head_dim,
+            dropout=dropout,
+            bias=attention_bias,
+            cross_attention_dim=cross_attention_dim if only_cross_attention else None,
+            upcast_attention=upcast_attention,
+            out_bias=attention_out_bias,
+            use_tpu_flash_attention=use_tpu_flash_attention,
+            qk_norm=qk_norm,
+            use_rope=use_rope,
+        )
+
+        # 2. Cross-Attn
+        if cross_attention_dim is not None or double_self_attention:
+            self.attn2 = Attention(
+                query_dim=dim,
+                cross_attention_dim=(
+                    cross_attention_dim if not double_self_attention else None
+                ),
+                heads=num_attention_heads,
+                dim_head=attention_head_dim,
+                dropout=dropout,
+                bias=attention_bias,
+                upcast_attention=upcast_attention,
+                out_bias=attention_out_bias,
+                use_tpu_flash_attention=use_tpu_flash_attention,
+                qk_norm=qk_norm,
+                use_rope=use_rope,
+            )  # is self-attn if encoder_hidden_states is none
+
+            if adaptive_norm == "none":
+                self.attn2_norm = make_norm_layer(
+                    dim, norm_eps, norm_elementwise_affine
+                )
+        else:
+            self.attn2 = None
+            self.attn2_norm = None
+
+        self.norm2 = make_norm_layer(dim, norm_eps, norm_elementwise_affine)
+
+        # 3. Feed-forward
+        self.ff = FeedForward(
+            dim,
+            dropout=dropout,
+            activation_fn=activation_fn,
+            final_dropout=final_dropout,
+            inner_dim=ff_inner_dim,
+            bias=ff_bias,
+        )
+
+        # 5. Scale-shift for PixArt-Alpha.
+        if adaptive_norm != "none":
+            num_ada_params = 4 if adaptive_norm == "single_scale" else 6
+            self.scale_shift_table = nn.Parameter(
+                torch.randn(num_ada_params, dim) / dim**0.5
+            )
+
+        # let chunk size default to None
+        self._chunk_size = None
+        self._chunk_dim = 0
+
+    def set_use_tpu_flash_attention(self):
+        r"""
+        Function sets the flag in this object and propagates down the children. The flag will enforce the usage of TPU
+        attention kernel.
+        """
+        self.use_tpu_flash_attention = True
+        self.attn1.set_use_tpu_flash_attention()
+        self.attn2.set_use_tpu_flash_attention()
+
+    def set_chunk_feed_forward(self, chunk_size: Optional[int], dim: int = 0):
+        # Sets chunk feed-forward
+        self._chunk_size = chunk_size
+        self._chunk_dim = dim
+
+    def forward(
+        self,
+        hidden_states: torch.FloatTensor,
+        freqs_cis: Optional[Tuple[torch.FloatTensor, torch.FloatTensor]] = None,
+        attention_mask: Optional[torch.FloatTensor] = None,
+        encoder_hidden_states: Optional[torch.FloatTensor] = None,
+        encoder_attention_mask: Optional[torch.FloatTensor] = None,
+        timestep: Optional[torch.LongTensor] = None,
+        cross_attention_kwargs: Dict[str, Any] = None,
+        class_labels: Optional[torch.LongTensor] = None,
+        added_cond_kwargs: Optional[Dict[str, torch.Tensor]] = None,
+        skip_layer_mask: Optional[torch.Tensor] = None,
+        skip_layer_strategy: Optional[SkipLayerStrategy] = None,
+    ) -> torch.FloatTensor:
+        if cross_attention_kwargs is not None:
+            if cross_attention_kwargs.get("scale", None) is not None:
+                logger.warning(
+                    "Passing `scale` to `cross_attention_kwargs` is depcrecated. `scale` will be ignored."
+                )
+
+        # Notice that normalization is always applied before the real computation in the following blocks.
+        # 0. Self-Attention
+        batch_size = hidden_states.shape[0]
+
+        original_hidden_states = hidden_states
+
+        norm_hidden_states = self.norm1(hidden_states)
+
+        # Apply ada_norm_single
+        if self.adaptive_norm in ["single_scale_shift", "single_scale"]:
+            assert timestep.ndim == 3  # [batch, 1 or num_tokens, embedding_dim]
+            num_ada_params = self.scale_shift_table.shape[0]
+            ada_values = self.scale_shift_table[None, None] + timestep.reshape(
+                batch_size, timestep.shape[1], num_ada_params, -1
+            )
+            if self.adaptive_norm == "single_scale_shift":
+                shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = (
+                    ada_values.unbind(dim=2)
+                )
+                norm_hidden_states = norm_hidden_states * (1 + scale_msa) + shift_msa
+            else:
+                scale_msa, gate_msa, scale_mlp, gate_mlp = ada_values.unbind(dim=2)
+                norm_hidden_states = norm_hidden_states * (1 + scale_msa)
+        elif self.adaptive_norm == "none":
+            scale_msa, gate_msa, scale_mlp, gate_mlp = None, None, None, None
+        else:
+            raise ValueError(f"Unknown adaptive norm type: {self.adaptive_norm}")
+
+        norm_hidden_states = norm_hidden_states.squeeze(
+            1
+        )  # TODO: Check if this is needed
+
+        # 1. Prepare GLIGEN inputs
+        cross_attention_kwargs = (
+            cross_attention_kwargs.copy() if cross_attention_kwargs is not None else {}
+        )
+
+        attn_output = self.attn1(
+            norm_hidden_states,
+            freqs_cis=freqs_cis,
+            encoder_hidden_states=(
+                encoder_hidden_states if self.only_cross_attention else None
+            ),
+            attention_mask=attention_mask,
+            skip_layer_mask=skip_layer_mask,
+            skip_layer_strategy=skip_layer_strategy,
+            **cross_attention_kwargs,
+        )
+        if gate_msa is not None:
+            attn_output = gate_msa * attn_output
+
+        hidden_states = attn_output + hidden_states
+        if hidden_states.ndim == 4:
+            hidden_states = hidden_states.squeeze(1)
+
+        # 3. Cross-Attention
+        if self.attn2 is not None:
+            if self.adaptive_norm == "none":
+                attn_input = self.attn2_norm(hidden_states)
+            else:
+                attn_input = hidden_states
+            attn_output = self.attn2(
+                attn_input,
+                freqs_cis=freqs_cis,
+                encoder_hidden_states=encoder_hidden_states,
+                attention_mask=encoder_attention_mask,
+                **cross_attention_kwargs,
+            )
+            hidden_states = attn_output + hidden_states
+
+        # 4. Feed-forward
+        norm_hidden_states = self.norm2(hidden_states)
+        if self.adaptive_norm == "single_scale_shift":
+            norm_hidden_states = norm_hidden_states * (1 + scale_mlp) + shift_mlp
+        elif self.adaptive_norm == "single_scale":
+            norm_hidden_states = norm_hidden_states * (1 + scale_mlp)
+        elif self.adaptive_norm == "none":
+            pass
+        else:
+            raise ValueError(f"Unknown adaptive norm type: {self.adaptive_norm}")
+
+        if self._chunk_size is not None:
+            # "feed_forward_chunk_size" can be used to save memory
+            ff_output = _chunked_feed_forward(
+                self.ff, norm_hidden_states, self._chunk_dim, self._chunk_size
+            )
+        else:
+            ff_output = self.ff(norm_hidden_states)
+        if gate_mlp is not None:
+            ff_output = gate_mlp * ff_output
+
+        hidden_states = ff_output + hidden_states
+        if hidden_states.ndim == 4:
+            hidden_states = hidden_states.squeeze(1)
+
+        if (
+            skip_layer_mask is not None
+            and skip_layer_strategy == SkipLayerStrategy.TransformerBlock
+        ):
+            skip_layer_mask = skip_layer_mask.view(-1, 1, 1)
+            hidden_states = hidden_states * skip_layer_mask + original_hidden_states * (
+                1.0 - skip_layer_mask
+            )
+
+        return hidden_states
+
+
+@maybe_allow_in_graph
+class Attention(nn.Module):
+    r"""
+    A cross attention layer.
+
+    Parameters:
+        query_dim (`int`):
+            The number of channels in the query.
+        cross_attention_dim (`int`, *optional*):
+            The number of channels in the encoder_hidden_states. If not given, defaults to `query_dim`.
+        heads (`int`,  *optional*, defaults to 8):
+            The number of heads to use for multi-head attention.
+        dim_head (`int`,  *optional*, defaults to 64):
+            The number of channels in each head.
+        dropout (`float`, *optional*, defaults to 0.0):
+            The dropout probability to use.
+        bias (`bool`, *optional*, defaults to False):
+            Set to `True` for the query, key, and value linear layers to contain a bias parameter.
+        upcast_attention (`bool`, *optional*, defaults to False):
+            Set to `True` to upcast the attention computation to `float32`.
+        upcast_softmax (`bool`, *optional*, defaults to False):
+            Set to `True` to upcast the softmax computation to `float32`.
+        cross_attention_norm (`str`, *optional*, defaults to `None`):
+            The type of normalization to use for the cross attention. Can be `None`, `layer_norm`, or `group_norm`.
+        cross_attention_norm_num_groups (`int`, *optional*, defaults to 32):
+            The number of groups to use for the group norm in the cross attention.
+        added_kv_proj_dim (`int`, *optional*, defaults to `None`):
+            The number of channels to use for the added key and value projections. If `None`, no projection is used.
+        norm_num_groups (`int`, *optional*, defaults to `None`):
+            The number of groups to use for the group norm in the attention.
+        spatial_norm_dim (`int`, *optional*, defaults to `None`):
+            The number of channels to use for the spatial normalization.
+        out_bias (`bool`, *optional*, defaults to `True`):
+            Set to `True` to use a bias in the output linear layer.
+        scale_qk (`bool`, *optional*, defaults to `True`):
+            Set to `True` to scale the query and key by `1 / sqrt(dim_head)`.
+        qk_norm (`str`, *optional*, defaults to None):
+            Set to 'layer_norm' or `rms_norm` to perform query and key normalization.
+        only_cross_attention (`bool`, *optional*, defaults to `False`):
+            Set to `True` to only use cross attention and not added_kv_proj_dim. Can only be set to `True` if
+            `added_kv_proj_dim` is not `None`.
+        eps (`float`, *optional*, defaults to 1e-5):
+            An additional value added to the denominator in group normalization that is used for numerical stability.
+        rescale_output_factor (`float`, *optional*, defaults to 1.0):
+            A factor to rescale the output by dividing it with this value.
+        residual_connection (`bool`, *optional*, defaults to `False`):
+            Set to `True` to add the residual connection to the output.
+        _from_deprecated_attn_block (`bool`, *optional*, defaults to `False`):
+            Set to `True` if the attention block is loaded from a deprecated state dict.
+        processor (`AttnProcessor`, *optional*, defaults to `None`):
+            The attention processor to use. If `None`, defaults to `AttnProcessor2_0` if `torch 2.x` is used and
+            `AttnProcessor` otherwise.
+    """
+
+    def __init__(
+        self,
+        query_dim: int,
+        cross_attention_dim: Optional[int] = None,
+        heads: int = 8,
+        dim_head: int = 64,
+        dropout: float = 0.0,
+        bias: bool = False,
+        upcast_attention: bool = False,
+        upcast_softmax: bool = False,
+        cross_attention_norm: Optional[str] = None,
+        cross_attention_norm_num_groups: int = 32,
+        added_kv_proj_dim: Optional[int] = None,
+        norm_num_groups: Optional[int] = None,
+        spatial_norm_dim: Optional[int] = None,
+        out_bias: bool = True,
+        scale_qk: bool = True,
+        qk_norm: Optional[str] = None,
+        only_cross_attention: bool = False,
+        eps: float = 1e-5,
+        rescale_output_factor: float = 1.0,
+        residual_connection: bool = False,
+        _from_deprecated_attn_block: bool = False,
+        processor: Optional["AttnProcessor"] = None,
+        out_dim: int = None,
+        use_tpu_flash_attention: bool = False,
+        use_rope: bool = False,
+    ):
+        super().__init__()
+        self.inner_dim = out_dim if out_dim is not None else dim_head * heads
+        self.query_dim = query_dim
+        self.use_bias = bias
+        self.is_cross_attention = cross_attention_dim is not None
+        self.cross_attention_dim = (
+            cross_attention_dim if cross_attention_dim is not None else query_dim
+        )
+        self.upcast_attention = upcast_attention
+        self.upcast_softmax = upcast_softmax
+        self.rescale_output_factor = rescale_output_factor
+        self.residual_connection = residual_connection
+        self.dropout = dropout
+        self.fused_projections = False
+        self.out_dim = out_dim if out_dim is not None else query_dim
+        self.use_tpu_flash_attention = use_tpu_flash_attention
+        self.use_rope = use_rope
+
+        # we make use of this private variable to know whether this class is loaded
+        # with an deprecated state dict so that we can convert it on the fly
+        self._from_deprecated_attn_block = _from_deprecated_attn_block
+
+        self.scale_qk = scale_qk
+        self.scale = dim_head**-0.5 if self.scale_qk else 1.0
+
+        if qk_norm is None:
+            self.q_norm = nn.Identity()
+            self.k_norm = nn.Identity()
+        elif qk_norm == "rms_norm":
+            self.q_norm = RMSNorm(dim_head * heads, eps=1e-5)
+            self.k_norm = RMSNorm(dim_head * heads, eps=1e-5)
+        elif qk_norm == "layer_norm":
+            self.q_norm = nn.LayerNorm(dim_head * heads, eps=1e-5)
+            self.k_norm = nn.LayerNorm(dim_head * heads, eps=1e-5)
+        else:
+            raise ValueError(f"Unsupported qk_norm method: {qk_norm}")
+
+        self.heads = out_dim // dim_head if out_dim is not None else heads
+        # for slice_size > 0 the attention score computation
+        # is split across the batch axis to save memory
+        # You can set slice_size with `set_attention_slice`
+        self.sliceable_head_dim = heads
+
+        self.added_kv_proj_dim = added_kv_proj_dim
+        self.only_cross_attention = only_cross_attention
+
+        if self.added_kv_proj_dim is None and self.only_cross_attention:
+            raise ValueError(
+                "`only_cross_attention` can only be set to True if `added_kv_proj_dim` is not None. Make sure to set either `only_cross_attention=False` or define `added_kv_proj_dim`."
+            )
+
+        if norm_num_groups is not None:
+            self.group_norm = nn.GroupNorm(
+                num_channels=query_dim, num_groups=norm_num_groups, eps=eps, affine=True
+            )
+        else:
+            self.group_norm = None
+
+        if spatial_norm_dim is not None:
+            self.spatial_norm = SpatialNorm(
+                f_channels=query_dim, zq_channels=spatial_norm_dim
+            )
+        else:
+            self.spatial_norm = None
+
+        if cross_attention_norm is None:
+            self.norm_cross = None
+        elif cross_attention_norm == "layer_norm":
+            self.norm_cross = nn.LayerNorm(self.cross_attention_dim)
+        elif cross_attention_norm == "group_norm":
+            if self.added_kv_proj_dim is not None:
+                # The given `encoder_hidden_states` are initially of shape
+                # (batch_size, seq_len, added_kv_proj_dim) before being projected
+                # to (batch_size, seq_len, cross_attention_dim). The norm is applied
+                # before the projection, so we need to use `added_kv_proj_dim` as
+                # the number of channels for the group norm.
+                norm_cross_num_channels = added_kv_proj_dim
+            else:
+                norm_cross_num_channels = self.cross_attention_dim
+
+            self.norm_cross = nn.GroupNorm(
+                num_channels=norm_cross_num_channels,
+                num_groups=cross_attention_norm_num_groups,
+                eps=1e-5,
+                affine=True,
+            )
+        else:
+            raise ValueError(
+                f"unknown cross_attention_norm: {cross_attention_norm}. Should be None, 'layer_norm' or 'group_norm'"
+            )
+
+        linear_cls = nn.Linear
+
+        self.linear_cls = linear_cls
+        self.to_q = linear_cls(query_dim, self.inner_dim, bias=bias)
+
+        if not self.only_cross_attention:
+            # only relevant for the `AddedKVProcessor` classes
+            self.to_k = linear_cls(self.cross_attention_dim, self.inner_dim, bias=bias)
+            self.to_v = linear_cls(self.cross_attention_dim, self.inner_dim, bias=bias)
+        else:
+            self.to_k = None
+            self.to_v = None
+
+        if self.added_kv_proj_dim is not None:
+            self.add_k_proj = linear_cls(added_kv_proj_dim, self.inner_dim)
+            self.add_v_proj = linear_cls(added_kv_proj_dim, self.inner_dim)
+
+        self.to_out = nn.ModuleList([])
+        self.to_out.append(linear_cls(self.inner_dim, self.out_dim, bias=out_bias))
+        self.to_out.append(nn.Dropout(dropout))
+
+        # set attention processor
+        # We use the AttnProcessor2_0 by default when torch 2.x is used which uses
+        # torch.nn.functional.scaled_dot_product_attention for native Flash/memory_efficient_attention
+        # but only if it has the default `scale` argument. TODO remove scale_qk check when we move to torch 2.1
+        if processor is None:
+            processor = AttnProcessor2_0()
+        self.set_processor(processor)
+
+    def set_use_tpu_flash_attention(self):
+        r"""
+        Function sets the flag in this object. The flag will enforce the usage of TPU attention kernel.
+        """
+        self.use_tpu_flash_attention = True
+
+    def set_processor(self, processor: "AttnProcessor") -> None:
+        r"""
+        Set the attention processor to use.
+
+        Args:
+            processor (`AttnProcessor`):
+                The attention processor to use.
+        """
+        # if current processor is in `self._modules` and if passed `processor` is not, we need to
+        # pop `processor` from `self._modules`
+        if (
+            hasattr(self, "processor")
+            and isinstance(self.processor, torch.nn.Module)
+            and not isinstance(processor, torch.nn.Module)
+        ):
+            logger.info(
+                f"You are removing possibly trained weights of {self.processor} with {processor}"
+            )
+            self._modules.pop("processor")
+
+        self.processor = processor
+
+    def get_processor(
+        self, return_deprecated_lora: bool = False
+    ) -> "AttentionProcessor":  # noqa: F821
+        r"""
+        Get the attention processor in use.
+
+        Args:
+            return_deprecated_lora (`bool`, *optional*, defaults to `False`):
+                Set to `True` to return the deprecated LoRA attention processor.
+
+        Returns:
+            "AttentionProcessor": The attention processor in use.
+        """
+        if not return_deprecated_lora:
+            return self.processor
+
+        # TODO(Sayak, Patrick). The rest of the function is needed to ensure backwards compatible
+        # serialization format for LoRA Attention Processors. It should be deleted once the integration
+        # with PEFT is completed.
+        is_lora_activated = {
+            name: module.lora_layer is not None
+            for name, module in self.named_modules()
+            if hasattr(module, "lora_layer")
+        }
+
+        # 1. if no layer has a LoRA activated we can return the processor as usual
+        if not any(is_lora_activated.values()):
+            return self.processor
+
+        # If doesn't apply LoRA do `add_k_proj` or `add_v_proj`
+        is_lora_activated.pop("add_k_proj", None)
+        is_lora_activated.pop("add_v_proj", None)
+        # 2. else it is not posssible that only some layers have LoRA activated
+        if not all(is_lora_activated.values()):
+            raise ValueError(
+                f"Make sure that either all layers or no layers have LoRA activated, but have {is_lora_activated}"
+            )
+
+        # 3. And we need to merge the current LoRA layers into the corresponding LoRA attention processor
+        non_lora_processor_cls_name = self.processor.__class__.__name__
+        lora_processor_cls = getattr(
+            import_module(__name__), "LoRA" + non_lora_processor_cls_name
+        )
+
+        hidden_size = self.inner_dim
+
+        # now create a LoRA attention processor from the LoRA layers
+        if lora_processor_cls in [
+            LoRAAttnProcessor,
+            LoRAAttnProcessor2_0,
+            LoRAXFormersAttnProcessor,
+        ]:
+            kwargs = {
+                "cross_attention_dim": self.cross_attention_dim,
+                "rank": self.to_q.lora_layer.rank,
+                "network_alpha": self.to_q.lora_layer.network_alpha,
+                "q_rank": self.to_q.lora_layer.rank,
+                "q_hidden_size": self.to_q.lora_layer.out_features,
+                "k_rank": self.to_k.lora_layer.rank,
+                "k_hidden_size": self.to_k.lora_layer.out_features,
+                "v_rank": self.to_v.lora_layer.rank,
+                "v_hidden_size": self.to_v.lora_layer.out_features,
+                "out_rank": self.to_out[0].lora_layer.rank,
+                "out_hidden_size": self.to_out[0].lora_layer.out_features,
+            }
+
+            if hasattr(self.processor, "attention_op"):
+                kwargs["attention_op"] = self.processor.attention_op
+
+            lora_processor = lora_processor_cls(hidden_size, **kwargs)
+            lora_processor.to_q_lora.load_state_dict(self.to_q.lora_layer.state_dict())
+            lora_processor.to_k_lora.load_state_dict(self.to_k.lora_layer.state_dict())
+            lora_processor.to_v_lora.load_state_dict(self.to_v.lora_layer.state_dict())
+            lora_processor.to_out_lora.load_state_dict(
+                self.to_out[0].lora_layer.state_dict()
+            )
+        elif lora_processor_cls == LoRAAttnAddedKVProcessor:
+            lora_processor = lora_processor_cls(
+                hidden_size,
+                cross_attention_dim=self.add_k_proj.weight.shape[0],
+                rank=self.to_q.lora_layer.rank,
+                network_alpha=self.to_q.lora_layer.network_alpha,
+            )
+            lora_processor.to_q_lora.load_state_dict(self.to_q.lora_layer.state_dict())
+            lora_processor.to_k_lora.load_state_dict(self.to_k.lora_layer.state_dict())
+            lora_processor.to_v_lora.load_state_dict(self.to_v.lora_layer.state_dict())
+            lora_processor.to_out_lora.load_state_dict(
+                self.to_out[0].lora_layer.state_dict()
+            )
+
+            # only save if used
+            if self.add_k_proj.lora_layer is not None:
+                lora_processor.add_k_proj_lora.load_state_dict(
+                    self.add_k_proj.lora_layer.state_dict()
+                )
+                lora_processor.add_v_proj_lora.load_state_dict(
+                    self.add_v_proj.lora_layer.state_dict()
+                )
+            else:
+                lora_processor.add_k_proj_lora = None
+                lora_processor.add_v_proj_lora = None
+        else:
+            raise ValueError(f"{lora_processor_cls} does not exist.")
+
+        return lora_processor
+
+    def forward(
+        self,
+        hidden_states: torch.FloatTensor,
+        freqs_cis: Optional[Tuple[torch.FloatTensor, torch.FloatTensor]] = None,
+        encoder_hidden_states: Optional[torch.FloatTensor] = None,
+        attention_mask: Optional[torch.FloatTensor] = None,
+        skip_layer_mask: Optional[torch.Tensor] = None,
+        skip_layer_strategy: Optional[SkipLayerStrategy] = None,
+        **cross_attention_kwargs,
+    ) -> torch.Tensor:
+        r"""
+        The forward method of the `Attention` class.
+
+        Args:
+            hidden_states (`torch.Tensor`):
+                The hidden states of the query.
+            encoder_hidden_states (`torch.Tensor`, *optional*):
+                The hidden states of the encoder.
+            attention_mask (`torch.Tensor`, *optional*):
+                The attention mask to use. If `None`, no mask is applied.
+            skip_layer_mask (`torch.Tensor`, *optional*):
+                The skip layer mask to use. If `None`, no mask is applied.
+            skip_layer_strategy (`SkipLayerStrategy`, *optional*, defaults to `None`):
+                Controls which layers to skip for spatiotemporal guidance.
+            **cross_attention_kwargs:
+                Additional keyword arguments to pass along to the cross attention.
+
+        Returns:
+            `torch.Tensor`: The output of the attention layer.
+        """
+        # The `Attention` class can call different attention processors / attention functions
+        # here we simply pass along all tensors to the selected processor class
+        # For standard processors that are defined here, `**cross_attention_kwargs` is empty
+
+        attn_parameters = set(
+            inspect.signature(self.processor.__call__).parameters.keys()
+        )
+        unused_kwargs = [
+            k for k, _ in cross_attention_kwargs.items() if k not in attn_parameters
+        ]
+        if len(unused_kwargs) > 0:
+            logger.warning(
+                f"cross_attention_kwargs {unused_kwargs} are not expected by"
+                f" {self.processor.__class__.__name__} and will be ignored."
+            )
+        cross_attention_kwargs = {
+            k: w for k, w in cross_attention_kwargs.items() if k in attn_parameters
+        }
+
+        return self.processor(
+            self,
+            hidden_states,
+            freqs_cis=freqs_cis,
+            encoder_hidden_states=encoder_hidden_states,
+            attention_mask=attention_mask,
+            skip_layer_mask=skip_layer_mask,
+            skip_layer_strategy=skip_layer_strategy,
+            **cross_attention_kwargs,
+        )
+
+    def batch_to_head_dim(self, tensor: torch.Tensor) -> torch.Tensor:
+        r"""
+        Reshape the tensor from `[batch_size, seq_len, dim]` to `[batch_size // heads, seq_len, dim * heads]`. `heads`
+        is the number of heads initialized while constructing the `Attention` class.
+
+        Args:
+            tensor (`torch.Tensor`): The tensor to reshape.
+
+        Returns:
+            `torch.Tensor`: The reshaped tensor.
+        """
+        head_size = self.heads
+        batch_size, seq_len, dim = tensor.shape
+        tensor = tensor.reshape(batch_size // head_size, head_size, seq_len, dim)
+        tensor = tensor.permute(0, 2, 1, 3).reshape(
+            batch_size // head_size, seq_len, dim * head_size
+        )
+        return tensor
+
+    def head_to_batch_dim(self, tensor: torch.Tensor, out_dim: int = 3) -> torch.Tensor:
+        r"""
+        Reshape the tensor from `[batch_size, seq_len, dim]` to `[batch_size, seq_len, heads, dim // heads]` `heads` is
+        the number of heads initialized while constructing the `Attention` class.
+
+        Args:
+            tensor (`torch.Tensor`): The tensor to reshape.
+            out_dim (`int`, *optional*, defaults to `3`): The output dimension of the tensor. If `3`, the tensor is
+                reshaped to `[batch_size * heads, seq_len, dim // heads]`.
+
+        Returns:
+            `torch.Tensor`: The reshaped tensor.
+        """
+
+        head_size = self.heads
+        if tensor.ndim == 3:
+            batch_size, seq_len, dim = tensor.shape
+            extra_dim = 1
+        else:
+            batch_size, extra_dim, seq_len, dim = tensor.shape
+        tensor = tensor.reshape(
+            batch_size, seq_len * extra_dim, head_size, dim // head_size
+        )
+        tensor = tensor.permute(0, 2, 1, 3)
+
+        if out_dim == 3:
+            tensor = tensor.reshape(
+                batch_size * head_size, seq_len * extra_dim, dim // head_size
+            )
+
+        return tensor
+
+    def get_attention_scores(
+        self,
+        query: torch.Tensor,
+        key: torch.Tensor,
+        attention_mask: torch.Tensor = None,
+    ) -> torch.Tensor:
+        r"""
+        Compute the attention scores.
+
+        Args:
+            query (`torch.Tensor`): The query tensor.
+            key (`torch.Tensor`): The key tensor.
+            attention_mask (`torch.Tensor`, *optional*): The attention mask to use. If `None`, no mask is applied.
+
+        Returns:
+            `torch.Tensor`: The attention probabilities/scores.
+        """
+        dtype = query.dtype
+        if self.upcast_attention:
+            query = query.float()
+            key = key.float()
+
+        if attention_mask is None:
+            baddbmm_input = torch.empty(
+                query.shape[0],
+                query.shape[1],
+                key.shape[1],
+                dtype=query.dtype,
+                device=query.device,
+            )
+            beta = 0
+        else:
+            baddbmm_input = attention_mask
+            beta = 1
+
+        attention_scores = torch.baddbmm(
+            baddbmm_input,
+            query,
+            key.transpose(-1, -2),
+            beta=beta,
+            alpha=self.scale,
+        )
+        del baddbmm_input
+
+        if self.upcast_softmax:
+            attention_scores = attention_scores.float()
+
+        attention_probs = attention_scores.softmax(dim=-1)
+        del attention_scores
+
+        attention_probs = attention_probs.to(dtype)
+
+        return attention_probs
+
+    def prepare_attention_mask(
+        self,
+        attention_mask: torch.Tensor,
+        target_length: int,
+        batch_size: int,
+        out_dim: int = 3,
+    ) -> torch.Tensor:
+        r"""
+        Prepare the attention mask for the attention computation.
+
+        Args:
+            attention_mask (`torch.Tensor`):
+                The attention mask to prepare.
+            target_length (`int`):
+                The target length of the attention mask. This is the length of the attention mask after padding.
+            batch_size (`int`):
+                The batch size, which is used to repeat the attention mask.
+            out_dim (`int`, *optional*, defaults to `3`):
+                The output dimension of the attention mask. Can be either `3` or `4`.
+
+        Returns:
+            `torch.Tensor`: The prepared attention mask.
+        """
+        head_size = self.heads
+        if attention_mask is None:
+            return attention_mask
+
+        current_length: int = attention_mask.shape[-1]
+        if current_length != target_length:
+            if attention_mask.device.type == "mps":
+                # HACK: MPS: Does not support padding by greater than dimension of input tensor.
+                # Instead, we can manually construct the padding tensor.
+                padding_shape = (
+                    attention_mask.shape[0],
+                    attention_mask.shape[1],
+                    target_length,
+                )
+                padding = torch.zeros(
+                    padding_shape,
+                    dtype=attention_mask.dtype,
+                    device=attention_mask.device,
+                )
+                attention_mask = torch.cat([attention_mask, padding], dim=2)
+            else:
+                # TODO: for pipelines such as stable-diffusion, padding cross-attn mask:
+                #       we want to instead pad by (0, remaining_length), where remaining_length is:
+                #       remaining_length: int = target_length - current_length
+                # TODO: re-enable tests/models/test_models_unet_2d_condition.py#test_model_xattn_padding
+                attention_mask = F.pad(attention_mask, (0, target_length), value=0.0)
+
+        if out_dim == 3:
+            if attention_mask.shape[0] < batch_size * head_size:
+                attention_mask = attention_mask.repeat_interleave(head_size, dim=0)
+        elif out_dim == 4:
+            attention_mask = attention_mask.unsqueeze(1)
+            attention_mask = attention_mask.repeat_interleave(head_size, dim=1)
+
+        return attention_mask
+
+    def norm_encoder_hidden_states(
+        self, encoder_hidden_states: torch.Tensor
+    ) -> torch.Tensor:
+        r"""
+        Normalize the encoder hidden states. Requires `self.norm_cross` to be specified when constructing the
+        `Attention` class.
+
+        Args:
+            encoder_hidden_states (`torch.Tensor`): Hidden states of the encoder.
+
+        Returns:
+            `torch.Tensor`: The normalized encoder hidden states.
+        """
+        assert (
+            self.norm_cross is not None
+        ), "self.norm_cross must be defined to call self.norm_encoder_hidden_states"
+
+        if isinstance(self.norm_cross, nn.LayerNorm):
+            encoder_hidden_states = self.norm_cross(encoder_hidden_states)
+        elif isinstance(self.norm_cross, nn.GroupNorm):
+            # Group norm norms along the channels dimension and expects
+            # input to be in the shape of (N, C, *). In this case, we want
+            # to norm along the hidden dimension, so we need to move
+            # (batch_size, sequence_length, hidden_size) ->
+            # (batch_size, hidden_size, sequence_length)
+            encoder_hidden_states = encoder_hidden_states.transpose(1, 2)
+            encoder_hidden_states = self.norm_cross(encoder_hidden_states)
+            encoder_hidden_states = encoder_hidden_states.transpose(1, 2)
+        else:
+            assert False
+
+        return encoder_hidden_states
+
+    @staticmethod
+    def apply_rotary_emb(
+        input_tensor: torch.Tensor,
+        freqs_cis: Tuple[torch.FloatTensor, torch.FloatTensor],
+    ) -> Tuple[torch.Tensor, torch.Tensor]:
+        cos_freqs = freqs_cis[0]
+        sin_freqs = freqs_cis[1]
+
+        t_dup = rearrange(input_tensor, "... (d r) -> ... d r", r=2)
+        t1, t2 = t_dup.unbind(dim=-1)
+        t_dup = torch.stack((-t2, t1), dim=-1)
+        input_tensor_rot = rearrange(t_dup, "... d r -> ... (d r)")
+
+        out = input_tensor * cos_freqs + input_tensor_rot * sin_freqs
+
+        return out
+
+
+class AttnProcessor2_0:
+    r"""
+    Processor for implementing scaled dot-product attention (enabled by default if you're using PyTorch 2.0).
+    """
+
+    def __init__(self):
+        pass
+
+    def __call__(
+        self,
+        attn: Attention,
+        hidden_states: torch.FloatTensor,
+        freqs_cis: Tuple[torch.FloatTensor, torch.FloatTensor],
+        encoder_hidden_states: Optional[torch.FloatTensor] = None,
+        attention_mask: Optional[torch.FloatTensor] = None,
+        temb: Optional[torch.FloatTensor] = None,
+        skip_layer_mask: Optional[torch.FloatTensor] = None,
+        skip_layer_strategy: Optional[SkipLayerStrategy] = None,
+        *args,
+        **kwargs,
+    ) -> torch.FloatTensor:
+        if len(args) > 0 or kwargs.get("scale", None) is not None:
+            deprecation_message = "The `scale` argument is deprecated and will be ignored. Please remove it, as passing it will raise an error in the future. `scale` should directly be passed while calling the underlying pipeline component i.e., via `cross_attention_kwargs`."
+            deprecate("scale", "1.0.0", deprecation_message)
+
+        residual = hidden_states
+        if attn.spatial_norm is not None:
+            hidden_states = attn.spatial_norm(hidden_states, temb)
+
+        input_ndim = hidden_states.ndim
+
+        if input_ndim == 4:
+            batch_size, channel, height, width = hidden_states.shape
+            hidden_states = hidden_states.view(
+                batch_size, channel, height * width
+            ).transpose(1, 2)
+
+        batch_size, sequence_length, _ = (
+            hidden_states.shape
+            if encoder_hidden_states is None
+            else encoder_hidden_states.shape
+        )
+
+        if skip_layer_mask is not None:
+            skip_layer_mask = skip_layer_mask.reshape(batch_size, 1, 1)
+
+        if (attention_mask is not None) and (not attn.use_tpu_flash_attention):
+            attention_mask = attn.prepare_attention_mask(
+                attention_mask, sequence_length, batch_size
+            )
+            # scaled_dot_product_attention expects attention_mask shape to be
+            # (batch, heads, source_length, target_length)
+            attention_mask = attention_mask.view(
+                batch_size, attn.heads, -1, attention_mask.shape[-1]
+            )
+
+        if attn.group_norm is not None:
+            hidden_states = attn.group_norm(hidden_states.transpose(1, 2)).transpose(
+                1, 2
+            )
+
+        query = attn.to_q(hidden_states)
+        query = attn.q_norm(query)
+
+        if encoder_hidden_states is not None:
+            if attn.norm_cross:
+                encoder_hidden_states = attn.norm_encoder_hidden_states(
+                    encoder_hidden_states
+                )
+            key = attn.to_k(encoder_hidden_states)
+            key = attn.k_norm(key)
+        else:  # if no context provided do self-attention
+            encoder_hidden_states = hidden_states
+            key = attn.to_k(hidden_states)
+            key = attn.k_norm(key)
+            if attn.use_rope:
+                key = attn.apply_rotary_emb(key, freqs_cis)
+                query = attn.apply_rotary_emb(query, freqs_cis)
+
+        value = attn.to_v(encoder_hidden_states)
+        value_for_stg = value
+
+        inner_dim = key.shape[-1]
+        head_dim = inner_dim // attn.heads
+
+        query = query.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
+        key = key.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
+        value = value.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
+
+        # the output of sdp = (batch, num_heads, seq_len, head_dim)
+
+        if attn.use_tpu_flash_attention:  # use tpu attention offload 'flash attention'
+            q_segment_indexes = None
+            if (
+                attention_mask is not None
+            ):  # if mask is required need to tune both segmenIds fields
+                # attention_mask = torch.squeeze(attention_mask).to(torch.float32)
+                attention_mask = attention_mask.to(torch.float32)
+                q_segment_indexes = torch.ones(
+                    batch_size, query.shape[2], device=query.device, dtype=torch.float32
+                )
+                assert (
+                    attention_mask.shape[1] == key.shape[2]
+                ), f"ERROR: KEY SHAPE must be same as attention mask [{key.shape[2]}, {attention_mask.shape[1]}]"
+
+            assert (
+                query.shape[2] % 128 == 0
+            ), f"ERROR: QUERY SHAPE must be divisible by 128 (TPU limitation) [{query.shape[2]}]"
+            assert (
+                key.shape[2] % 128 == 0
+            ), f"ERROR: KEY SHAPE must be divisible by 128 (TPU limitation) [{key.shape[2]}]"
+
+            # run the TPU kernel implemented in jax with pallas
+            hidden_states_a = flash_attention(
+                q=query,
+                k=key,
+                v=value,
+                q_segment_ids=q_segment_indexes,
+                kv_segment_ids=attention_mask,
+                sm_scale=attn.scale,
+            )
+        else:
+            hidden_states_a = F.scaled_dot_product_attention(
+                query,
+                key,
+                value,
+                attn_mask=attention_mask,
+                dropout_p=0.0,
+                is_causal=False,
+            )
+
+        hidden_states_a = hidden_states_a.transpose(1, 2).reshape(
+            batch_size, -1, attn.heads * head_dim
+        )
+        hidden_states_a = hidden_states_a.to(query.dtype)
+
+        if (
+            skip_layer_mask is not None
+            and skip_layer_strategy == SkipLayerStrategy.AttentionSkip
+        ):
+            hidden_states = hidden_states_a * skip_layer_mask + hidden_states * (
+                1.0 - skip_layer_mask
+            )
+        elif (
+            skip_layer_mask is not None
+            and skip_layer_strategy == SkipLayerStrategy.AttentionValues
+        ):
+            hidden_states = hidden_states_a * skip_layer_mask + value_for_stg * (
+                1.0 - skip_layer_mask
+            )
+        else:
+            hidden_states = hidden_states_a
+
+        # linear proj
+        hidden_states = attn.to_out[0](hidden_states)
+        # dropout
+        hidden_states = attn.to_out[1](hidden_states)
+
+        if input_ndim == 4:
+            hidden_states = hidden_states.transpose(-1, -2).reshape(
+                batch_size, channel, height, width
+            )
+            if (
+                skip_layer_mask is not None
+                and skip_layer_strategy == SkipLayerStrategy.Residual
+            ):
+                skip_layer_mask = skip_layer_mask.reshape(batch_size, 1, 1, 1)
+
+        if attn.residual_connection:
+            if (
+                skip_layer_mask is not None
+                and skip_layer_strategy == SkipLayerStrategy.Residual
+            ):
+                hidden_states = hidden_states + residual * skip_layer_mask
+            else:
+                hidden_states = hidden_states + residual
+
+        hidden_states = hidden_states / attn.rescale_output_factor
+
+        return hidden_states
+
+
+class AttnProcessor:
+    r"""
+    Default processor for performing attention-related computations.
+    """
+
+    def __call__(
+        self,
+        attn: Attention,
+        hidden_states: torch.FloatTensor,
+        encoder_hidden_states: Optional[torch.FloatTensor] = None,
+        attention_mask: Optional[torch.FloatTensor] = None,
+        temb: Optional[torch.FloatTensor] = None,
+        *args,
+        **kwargs,
+    ) -> torch.Tensor:
+        if len(args) > 0 or kwargs.get("scale", None) is not None:
+            deprecation_message = "The `scale` argument is deprecated and will be ignored. Please remove it, as passing it will raise an error in the future. `scale` should directly be passed while calling the underlying pipeline component i.e., via `cross_attention_kwargs`."
+            deprecate("scale", "1.0.0", deprecation_message)
+
+        residual = hidden_states
+
+        if attn.spatial_norm is not None:
+            hidden_states = attn.spatial_norm(hidden_states, temb)
+
+        input_ndim = hidden_states.ndim
+
+        if input_ndim == 4:
+            batch_size, channel, height, width = hidden_states.shape
+            hidden_states = hidden_states.view(
+                batch_size, channel, height * width
+            ).transpose(1, 2)
+
+        batch_size, sequence_length, _ = (
+            hidden_states.shape
+            if encoder_hidden_states is None
+            else encoder_hidden_states.shape
+        )
+        attention_mask = attn.prepare_attention_mask(
+            attention_mask, sequence_length, batch_size
+        )
+
+        if attn.group_norm is not None:
+            hidden_states = attn.group_norm(hidden_states.transpose(1, 2)).transpose(
+                1, 2
+            )
+
+        query = attn.to_q(hidden_states)
+
+        if encoder_hidden_states is None:
+            encoder_hidden_states = hidden_states
+        elif attn.norm_cross:
+            encoder_hidden_states = attn.norm_encoder_hidden_states(
+                encoder_hidden_states
+            )
+
+        key = attn.to_k(encoder_hidden_states)
+        value = attn.to_v(encoder_hidden_states)
+
+        query = attn.head_to_batch_dim(query)
+        key = attn.head_to_batch_dim(key)
+        value = attn.head_to_batch_dim(value)
+
+        query = attn.q_norm(query)
+        key = attn.k_norm(key)
+
+        attention_probs = attn.get_attention_scores(query, key, attention_mask)
+        hidden_states = torch.bmm(attention_probs, value)
+        hidden_states = attn.batch_to_head_dim(hidden_states)
+
+        # linear proj
+        hidden_states = attn.to_out[0](hidden_states)
+        # dropout
+        hidden_states = attn.to_out[1](hidden_states)
+
+        if input_ndim == 4:
+            hidden_states = hidden_states.transpose(-1, -2).reshape(
+                batch_size, channel, height, width
+            )
+
+        if attn.residual_connection:
+            hidden_states = hidden_states + residual
+
+        hidden_states = hidden_states / attn.rescale_output_factor
+
+        return hidden_states
+
+
+class FeedForward(nn.Module):
+    r"""
+    A feed-forward layer.
+
+    Parameters:
+        dim (`int`): The number of channels in the input.
+        dim_out (`int`, *optional*): The number of channels in the output. If not given, defaults to `dim`.
+        mult (`int`, *optional*, defaults to 4): The multiplier to use for the hidden dimension.
+        dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
+        activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward.
+        final_dropout (`bool` *optional*, defaults to False): Apply a final dropout.
+        bias (`bool`, defaults to True): Whether to use a bias in the linear layer.
+    """
+
+    def __init__(
+        self,
+        dim: int,
+        dim_out: Optional[int] = None,
+        mult: int = 4,
+        dropout: float = 0.0,
+        activation_fn: str = "geglu",
+        final_dropout: bool = False,
+        inner_dim=None,
+        bias: bool = True,
+    ):
+        super().__init__()
+        if inner_dim is None:
+            inner_dim = int(dim * mult)
+        dim_out = dim_out if dim_out is not None else dim
+        linear_cls = nn.Linear
+
+        if activation_fn == "gelu":
+            act_fn = GELU(dim, inner_dim, bias=bias)
+        elif activation_fn == "gelu-approximate":
+            act_fn = GELU(dim, inner_dim, approximate="tanh", bias=bias)
+        elif activation_fn == "geglu":
+            act_fn = GEGLU(dim, inner_dim, bias=bias)
+        elif activation_fn == "geglu-approximate":
+            act_fn = ApproximateGELU(dim, inner_dim, bias=bias)
+        else:
+            raise ValueError(f"Unsupported activation function: {activation_fn}")
+
+        self.net = nn.ModuleList([])
+        # project in
+        self.net.append(act_fn)
+        # project dropout
+        self.net.append(nn.Dropout(dropout))
+        # project out
+        self.net.append(linear_cls(inner_dim, dim_out, bias=bias))
+        # FF as used in Vision Transformer, MLP-Mixer, etc. have a final dropout
+        if final_dropout:
+            self.net.append(nn.Dropout(dropout))
+
+    def forward(self, hidden_states: torch.Tensor, scale: float = 1.0) -> torch.Tensor:
+        compatible_cls = (GEGLU, LoRACompatibleLinear)
+        for module in self.net:
+            if isinstance(module, compatible_cls):
+                hidden_states = module(hidden_states, scale)
+            else:
+                hidden_states = module(hidden_states)
+        return hidden_states

ltx_video/models/transformers/embeddings.py

@@ -0,0 +1,129 @@
+# Adapted from: https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/embeddings.py
+import math
+
+import numpy as np
+import torch
+from einops import rearrange
+from torch import nn
+
+
+def get_timestep_embedding(
+    timesteps: torch.Tensor,
+    embedding_dim: int,
+    flip_sin_to_cos: bool = False,
+    downscale_freq_shift: float = 1,
+    scale: float = 1,
+    max_period: int = 10000,
+):
+    """
+    This matches the implementation in Denoising Diffusion Probabilistic Models: Create sinusoidal timestep embeddings.
+
+    :param timesteps: a 1-D Tensor of N indices, one per batch element.
+                      These may be fractional.
+    :param embedding_dim: the dimension of the output. :param max_period: controls the minimum frequency of the
+    embeddings. :return: an [N x dim] Tensor of positional embeddings.
+    """
+    assert len(timesteps.shape) == 1, "Timesteps should be a 1d-array"
+
+    half_dim = embedding_dim // 2
+    exponent = -math.log(max_period) * torch.arange(
+        start=0, end=half_dim, dtype=torch.float32, device=timesteps.device
+    )
+    exponent = exponent / (half_dim - downscale_freq_shift)
+
+    emb = torch.exp(exponent)
+    emb = timesteps[:, None].float() * emb[None, :]
+
+    # scale embeddings
+    emb = scale * emb
+
+    # concat sine and cosine embeddings
+    emb = torch.cat([torch.sin(emb), torch.cos(emb)], dim=-1)
+
+    # flip sine and cosine embeddings
+    if flip_sin_to_cos:
+        emb = torch.cat([emb[:, half_dim:], emb[:, :half_dim]], dim=-1)
+
+    # zero pad
+    if embedding_dim % 2 == 1:
+        emb = torch.nn.functional.pad(emb, (0, 1, 0, 0))
+    return emb
+
+
+def get_3d_sincos_pos_embed(embed_dim, grid, w, h, f):
+    """
+    grid_size: int of the grid height and width return: pos_embed: [grid_size*grid_size, embed_dim] or
+    [1+grid_size*grid_size, embed_dim] (w/ or w/o cls_token)
+    """
+    grid = rearrange(grid, "c (f h w) -> c f h w", h=h, w=w)
+    grid = rearrange(grid, "c f h w -> c h w f", h=h, w=w)
+    grid = grid.reshape([3, 1, w, h, f])
+    pos_embed = get_3d_sincos_pos_embed_from_grid(embed_dim, grid)
+    pos_embed = pos_embed.transpose(1, 0, 2, 3)
+    return rearrange(pos_embed, "h w f c -> (f h w) c")
+
+
+def get_3d_sincos_pos_embed_from_grid(embed_dim, grid):
+    if embed_dim % 3 != 0:
+        raise ValueError("embed_dim must be divisible by 3")
+
+    # use half of dimensions to encode grid_h
+    emb_f = get_1d_sincos_pos_embed_from_grid(embed_dim // 3, grid[0])  # (H*W*T, D/3)
+    emb_h = get_1d_sincos_pos_embed_from_grid(embed_dim // 3, grid[1])  # (H*W*T, D/3)
+    emb_w = get_1d_sincos_pos_embed_from_grid(embed_dim // 3, grid[2])  # (H*W*T, D/3)
+
+    emb = np.concatenate([emb_h, emb_w, emb_f], axis=-1)  # (H*W*T, D)
+    return emb
+
+
+def get_1d_sincos_pos_embed_from_grid(embed_dim, pos):
+    """
+    embed_dim: output dimension for each position pos: a list of positions to be encoded: size (M,) out: (M, D)
+    """
+    if embed_dim % 2 != 0:
+        raise ValueError("embed_dim must be divisible by 2")
+
+    omega = np.arange(embed_dim // 2, dtype=np.float64)
+    omega /= embed_dim / 2.0
+    omega = 1.0 / 10000**omega  # (D/2,)
+
+    pos_shape = pos.shape
+
+    pos = pos.reshape(-1)
+    out = np.einsum("m,d->md", pos, omega)  # (M, D/2), outer product
+    out = out.reshape([*pos_shape, -1])[0]
+
+    emb_sin = np.sin(out)  # (M, D/2)
+    emb_cos = np.cos(out)  # (M, D/2)
+
+    emb = np.concatenate([emb_sin, emb_cos], axis=-1)  # (M, D)
+    return emb
+
+
+class SinusoidalPositionalEmbedding(nn.Module):
+    """Apply positional information to a sequence of embeddings.
+
+    Takes in a sequence of embeddings with shape (batch_size, seq_length, embed_dim) and adds positional embeddings to
+    them
+
+    Args:
+        embed_dim: (int): Dimension of the positional embedding.
+        max_seq_length: Maximum sequence length to apply positional embeddings
+
+    """
+
+    def __init__(self, embed_dim: int, max_seq_length: int = 32):
+        super().__init__()
+        position = torch.arange(max_seq_length).unsqueeze(1)
+        div_term = torch.exp(
+            torch.arange(0, embed_dim, 2) * (-math.log(10000.0) / embed_dim)
+        )
+        pe = torch.zeros(1, max_seq_length, embed_dim)
+        pe[0, :, 0::2] = torch.sin(position * div_term)
+        pe[0, :, 1::2] = torch.cos(position * div_term)
+        self.register_buffer("pe", pe)
+
+    def forward(self, x):
+        _, seq_length, _ = x.shape
+        x = x + self.pe[:, :seq_length]
+        return x

ltx_video/models/transformers/symmetric_patchifier.py

@@ -0,0 +1,84 @@
+from abc import ABC, abstractmethod
+from typing import Tuple
+
+import torch
+from diffusers.configuration_utils import ConfigMixin
+from einops import rearrange
+from torch import Tensor
+
+
+class Patchifier(ConfigMixin, ABC):
+    def __init__(self, patch_size: int):
+        super().__init__()
+        self._patch_size = (1, patch_size, patch_size)
+
+    @abstractmethod
+    def patchify(self, latents: Tensor) -> Tuple[Tensor, Tensor]:
+        raise NotImplementedError("Patchify method not implemented")
+
+    @abstractmethod
+    def unpatchify(
+        self,
+        latents: Tensor,
+        output_height: int,
+        output_width: int,
+        out_channels: int,
+    ) -> Tuple[Tensor, Tensor]:
+        pass
+
+    @property
+    def patch_size(self):
+        return self._patch_size
+
+    def get_latent_coords(
+        self, latent_num_frames, latent_height, latent_width, batch_size, device
+    ):
+        """
+        Return a tensor of shape [batch_size, 3, num_patches] containing the
+            top-left corner latent coordinates of each latent patch.
+        The tensor is repeated for each batch element.
+        """
+        latent_sample_coords = torch.meshgrid(
+            torch.arange(0, latent_num_frames, self._patch_size[0], device=device),
+            torch.arange(0, latent_height, self._patch_size[1], device=device),
+            torch.arange(0, latent_width, self._patch_size[2], device=device),
+        )
+        latent_sample_coords = torch.stack(latent_sample_coords, dim=0)
+        latent_coords = latent_sample_coords.unsqueeze(0).repeat(batch_size, 1, 1, 1, 1)
+        latent_coords = rearrange(
+            latent_coords, "b c f h w -> b c (f h w)", b=batch_size
+        )
+        return latent_coords
+
+
+class SymmetricPatchifier(Patchifier):
+    def patchify(self, latents: Tensor) -> Tuple[Tensor, Tensor]:
+        b, _, f, h, w = latents.shape
+        latent_coords = self.get_latent_coords(f, h, w, b, latents.device)
+        latents = rearrange(
+            latents,
+            "b c (f p1) (h p2) (w p3) -> b (f h w) (c p1 p2 p3)",
+            p1=self._patch_size[0],
+            p2=self._patch_size[1],
+            p3=self._patch_size[2],
+        )
+        return latents, latent_coords
+
+    def unpatchify(
+        self,
+        latents: Tensor,
+        output_height: int,
+        output_width: int,
+        out_channels: int,
+    ) -> Tuple[Tensor, Tensor]:
+        output_height = output_height // self._patch_size[1]
+        output_width = output_width // self._patch_size[2]
+        latents = rearrange(
+            latents,
+            "b (f h w) (c p q) -> b c f (h p) (w q)",
+            h=output_height,
+            w=output_width,
+            p=self._patch_size[1],
+            q=self._patch_size[2],
+        )
+        return latents

ltx_video/models/transformers/transformer3d.py

@@ -0,0 +1,507 @@
+# Adapted from: https://github.com/huggingface/diffusers/blob/v0.26.3/src/diffusers/models/transformers/transformer_2d.py
+import math
+from dataclasses import dataclass
+from typing import Any, Dict, List, Optional, Union
+import os
+import json
+import glob
+from pathlib import Path
+
+import torch
+from diffusers.configuration_utils import ConfigMixin, register_to_config
+from diffusers.models.embeddings import PixArtAlphaTextProjection
+from diffusers.models.modeling_utils import ModelMixin
+from diffusers.models.normalization import AdaLayerNormSingle
+from diffusers.utils import BaseOutput, is_torch_version
+from diffusers.utils import logging
+from torch import nn
+from safetensors import safe_open
+
+
+from ltx_video.models.transformers.attention import BasicTransformerBlock
+from ltx_video.utils.skip_layer_strategy import SkipLayerStrategy
+
+from ltx_video.utils.diffusers_config_mapping import (
+    diffusers_and_ours_config_mapping,
+    make_hashable_key,
+    TRANSFORMER_KEYS_RENAME_DICT,
+)
+
+
+logger = logging.get_logger(__name__)
+
+
+@dataclass
+class Transformer3DModelOutput(BaseOutput):
+    """
+    The output of [`Transformer2DModel`].
+
+    Args:
+        sample (`torch.FloatTensor` of shape `(batch_size, num_channels, height, width)` or `(batch size, num_vector_embeds - 1, num_latent_pixels)` if [`Transformer2DModel`] is discrete):
+            The hidden states output conditioned on the `encoder_hidden_states` input. If discrete, returns probability
+            distributions for the unnoised latent pixels.
+    """
+
+    sample: torch.FloatTensor
+
+
+class Transformer3DModel(ModelMixin, ConfigMixin):
+    _supports_gradient_checkpointing = True
+
+    @register_to_config
+    def __init__(
+        self,
+        num_attention_heads: int = 16,
+        attention_head_dim: int = 88,
+        in_channels: Optional[int] = None,
+        out_channels: Optional[int] = None,
+        num_layers: int = 1,
+        dropout: float = 0.0,
+        norm_num_groups: int = 32,
+        cross_attention_dim: Optional[int] = None,
+        attention_bias: bool = False,
+        num_vector_embeds: Optional[int] = None,
+        activation_fn: str = "geglu",
+        num_embeds_ada_norm: Optional[int] = None,
+        use_linear_projection: bool = False,
+        only_cross_attention: bool = False,
+        double_self_attention: bool = False,
+        upcast_attention: bool = False,
+        adaptive_norm: str = "single_scale_shift",  # 'single_scale_shift' or 'single_scale'
+        standardization_norm: str = "layer_norm",  # 'layer_norm' or 'rms_norm'
+        norm_elementwise_affine: bool = True,
+        norm_eps: float = 1e-5,
+        attention_type: str = "default",
+        caption_channels: int = None,
+        use_tpu_flash_attention: bool = False,  # if True uses the TPU attention offload ('flash attention')
+        qk_norm: Optional[str] = None,
+        positional_embedding_type: str = "rope",
+        positional_embedding_theta: Optional[float] = None,
+        positional_embedding_max_pos: Optional[List[int]] = None,
+        timestep_scale_multiplier: Optional[float] = None,
+        causal_temporal_positioning: bool = False,  # For backward compatibility, will be deprecated
+    ):
+        super().__init__()
+        self.use_tpu_flash_attention = (
+            use_tpu_flash_attention  # FIXME: push config down to the attention modules
+        )
+        self.use_linear_projection = use_linear_projection
+        self.num_attention_heads = num_attention_heads
+        self.attention_head_dim = attention_head_dim
+        inner_dim = num_attention_heads * attention_head_dim
+        self.inner_dim = inner_dim
+        self.patchify_proj = nn.Linear(in_channels, inner_dim, bias=True)
+        self.positional_embedding_type = positional_embedding_type
+        self.positional_embedding_theta = positional_embedding_theta
+        self.positional_embedding_max_pos = positional_embedding_max_pos
+        self.use_rope = self.positional_embedding_type == "rope"
+        self.timestep_scale_multiplier = timestep_scale_multiplier
+
+        if self.positional_embedding_type == "absolute":
+            raise ValueError("Absolute positional embedding is no longer supported")
+        elif self.positional_embedding_type == "rope":
+            if positional_embedding_theta is None:
+                raise ValueError(
+                    "If `positional_embedding_type` type is rope, `positional_embedding_theta` must also be defined"
+                )
+            if positional_embedding_max_pos is None:
+                raise ValueError(
+                    "If `positional_embedding_type` type is rope, `positional_embedding_max_pos` must also be defined"
+                )
+
+        # 3. Define transformers blocks
+        self.transformer_blocks = nn.ModuleList(
+            [
+                BasicTransformerBlock(
+                    inner_dim,
+                    num_attention_heads,
+                    attention_head_dim,
+                    dropout=dropout,
+                    cross_attention_dim=cross_attention_dim,
+                    activation_fn=activation_fn,
+                    num_embeds_ada_norm=num_embeds_ada_norm,
+                    attention_bias=attention_bias,
+                    only_cross_attention=only_cross_attention,
+                    double_self_attention=double_self_attention,
+                    upcast_attention=upcast_attention,
+                    adaptive_norm=adaptive_norm,
+                    standardization_norm=standardization_norm,
+                    norm_elementwise_affine=norm_elementwise_affine,
+                    norm_eps=norm_eps,
+                    attention_type=attention_type,
+                    use_tpu_flash_attention=use_tpu_flash_attention,
+                    qk_norm=qk_norm,
+                    use_rope=self.use_rope,
+                )
+                for d in range(num_layers)
+            ]
+        )
+
+        # 4. Define output layers
+        self.out_channels = in_channels if out_channels is None else out_channels
+        self.norm_out = nn.LayerNorm(inner_dim, elementwise_affine=False, eps=1e-6)
+        self.scale_shift_table = nn.Parameter(
+            torch.randn(2, inner_dim) / inner_dim**0.5
+        )
+        self.proj_out = nn.Linear(inner_dim, self.out_channels)
+
+        self.adaln_single = AdaLayerNormSingle(
+            inner_dim, use_additional_conditions=False
+        )
+        if adaptive_norm == "single_scale":
+            self.adaln_single.linear = nn.Linear(inner_dim, 4 * inner_dim, bias=True)
+
+        self.caption_projection = None
+        if caption_channels is not None:
+            self.caption_projection = PixArtAlphaTextProjection(
+                in_features=caption_channels, hidden_size=inner_dim
+            )
+
+        self.gradient_checkpointing = False
+
+    def set_use_tpu_flash_attention(self):
+        r"""
+        Function sets the flag in this object and propagates down the children. The flag will enforce the usage of TPU
+        attention kernel.
+        """
+        logger.info("ENABLE TPU FLASH ATTENTION -> TRUE")
+        self.use_tpu_flash_attention = True
+        # push config down to the attention modules
+        for block in self.transformer_blocks:
+            block.set_use_tpu_flash_attention()
+
+    def create_skip_layer_mask(
+        self,
+        batch_size: int,
+        num_conds: int,
+        ptb_index: int,
+        skip_block_list: Optional[List[int]] = None,
+    ):
+        if skip_block_list is None or len(skip_block_list) == 0:
+            return None
+        num_layers = len(self.transformer_blocks)
+        mask = torch.ones(
+            (num_layers, batch_size * num_conds), device=self.device, dtype=self.dtype
+        )
+        for block_idx in skip_block_list:
+            mask[block_idx, ptb_index::num_conds] = 0
+        return mask
+
+    def _set_gradient_checkpointing(self, module, value=False):
+        if hasattr(module, "gradient_checkpointing"):
+            module.gradient_checkpointing = value
+
+    def get_fractional_positions(self, indices_grid):
+        fractional_positions = torch.stack(
+            [
+                indices_grid[:, i] / self.positional_embedding_max_pos[i]
+                for i in range(3)
+            ],
+            dim=-1,
+        )
+        return fractional_positions
+
+    def precompute_freqs_cis(self, indices_grid, spacing="exp"):
+        dtype = torch.float32  # We need full precision in the freqs_cis computation.
+        dim = self.inner_dim
+        theta = self.positional_embedding_theta
+
+        fractional_positions = self.get_fractional_positions(indices_grid)
+
+        start = 1
+        end = theta
+        device = fractional_positions.device
+        if spacing == "exp":
+            indices = theta ** (
+                torch.linspace(
+                    math.log(start, theta),
+                    math.log(end, theta),
+                    dim // 6,
+                    device=device,
+                    dtype=dtype,
+                )
+            )
+            indices = indices.to(dtype=dtype)
+        elif spacing == "exp_2":
+            indices = 1.0 / theta ** (torch.arange(0, dim, 6, device=device) / dim)
+            indices = indices.to(dtype=dtype)
+        elif spacing == "linear":
+            indices = torch.linspace(start, end, dim // 6, device=device, dtype=dtype)
+        elif spacing == "sqrt":
+            indices = torch.linspace(
+                start**2, end**2, dim // 6, device=device, dtype=dtype
+            ).sqrt()
+
+        indices = indices * math.pi / 2
+
+        if spacing == "exp_2":
+            freqs = (
+                (indices * fractional_positions.unsqueeze(-1))
+                .transpose(-1, -2)
+                .flatten(2)
+            )
+        else:
+            freqs = (
+                (indices * (fractional_positions.unsqueeze(-1) * 2 - 1))
+                .transpose(-1, -2)
+                .flatten(2)
+            )
+
+        cos_freq = freqs.cos().repeat_interleave(2, dim=-1)
+        sin_freq = freqs.sin().repeat_interleave(2, dim=-1)
+        if dim % 6 != 0:
+            cos_padding = torch.ones_like(cos_freq[:, :, : dim % 6])
+            sin_padding = torch.zeros_like(cos_freq[:, :, : dim % 6])
+            cos_freq = torch.cat([cos_padding, cos_freq], dim=-1)
+            sin_freq = torch.cat([sin_padding, sin_freq], dim=-1)
+        return cos_freq.to(self.dtype), sin_freq.to(self.dtype)
+
+    def load_state_dict(
+        self,
+        state_dict: Dict,
+        *args,
+        **kwargs,
+    ):
+        if any([key.startswith("model.diffusion_model.") for key in state_dict.keys()]):
+            state_dict = {
+                key.replace("model.diffusion_model.", ""): value
+                for key, value in state_dict.items()
+                if key.startswith("model.diffusion_model.")
+            }
+        super().load_state_dict(state_dict, **kwargs)
+
+    @classmethod
+    def from_pretrained(
+        cls,
+        pretrained_model_path: Optional[Union[str, os.PathLike]],
+        *args,
+        **kwargs,
+    ):
+        pretrained_model_path = Path(pretrained_model_path)
+        if pretrained_model_path.is_dir():
+            config_path = pretrained_model_path / "transformer" / "config.json"
+            with open(config_path, "r") as f:
+                config = make_hashable_key(json.load(f))
+
+            assert config in diffusers_and_ours_config_mapping, (
+                "Provided diffusers checkpoint config for transformer is not suppported. "
+                "We only support diffusers configs found in Lightricks/LTX-Video."
+            )
+
+            config = diffusers_and_ours_config_mapping[config]
+            state_dict = {}
+            ckpt_paths = (
+                pretrained_model_path
+                / "transformer"
+                / "diffusion_pytorch_model*.safetensors"
+            )
+            dict_list = glob.glob(str(ckpt_paths))
+            for dict_path in dict_list:
+                part_dict = {}
+                with safe_open(dict_path, framework="pt", device="cpu") as f:
+                    for k in f.keys():
+                        part_dict[k] = f.get_tensor(k)
+                state_dict.update(part_dict)
+
+            for key in list(state_dict.keys()):
+                new_key = key
+                for replace_key, rename_key in TRANSFORMER_KEYS_RENAME_DICT.items():
+                    new_key = new_key.replace(replace_key, rename_key)
+                state_dict[new_key] = state_dict.pop(key)
+
+            with torch.device("meta"):
+                transformer = cls.from_config(config)
+            transformer.load_state_dict(state_dict, assign=True, strict=True)
+        elif pretrained_model_path.is_file() and str(pretrained_model_path).endswith(
+            ".safetensors"
+        ):
+            comfy_single_file_state_dict = {}
+            with safe_open(pretrained_model_path, framework="pt", device="cpu") as f:
+                metadata = f.metadata()
+                for k in f.keys():
+                    comfy_single_file_state_dict[k] = f.get_tensor(k)
+            configs = json.loads(metadata["config"])
+            transformer_config = configs["transformer"]
+            with torch.device("meta"):
+                transformer = Transformer3DModel.from_config(transformer_config)
+            transformer.load_state_dict(comfy_single_file_state_dict, assign=True)
+        return transformer
+
+    def forward(
+        self,
+        hidden_states: torch.Tensor,
+        indices_grid: torch.Tensor,
+        encoder_hidden_states: Optional[torch.Tensor] = None,
+        timestep: Optional[torch.LongTensor] = None,
+        class_labels: Optional[torch.LongTensor] = None,
+        cross_attention_kwargs: Dict[str, Any] = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        encoder_attention_mask: Optional[torch.Tensor] = None,
+        skip_layer_mask: Optional[torch.Tensor] = None,
+        skip_layer_strategy: Optional[SkipLayerStrategy] = None,
+        return_dict: bool = True,
+    ):
+        """
+        The [`Transformer2DModel`] forward method.
+
+        Args:
+            hidden_states (`torch.LongTensor` of shape `(batch size, num latent pixels)` if discrete, `torch.FloatTensor` of shape `(batch size, channel, height, width)` if continuous):
+                Input `hidden_states`.
+            indices_grid (`torch.LongTensor` of shape `(batch size, 3, num latent pixels)`):
+            encoder_hidden_states ( `torch.FloatTensor` of shape `(batch size, sequence len, embed dims)`, *optional*):
+                Conditional embeddings for cross attention layer. If not given, cross-attention defaults to
+                self-attention.
+            timestep ( `torch.LongTensor`, *optional*):
+                Used to indicate denoising step. Optional timestep to be applied as an embedding in `AdaLayerNorm`.
+            class_labels ( `torch.LongTensor` of shape `(batch size, num classes)`, *optional*):
+                Used to indicate class labels conditioning. Optional class labels to be applied as an embedding in
+                `AdaLayerZeroNorm`.
+            cross_attention_kwargs ( `Dict[str, Any]`, *optional*):
+                A kwargs dictionary that if specified is passed along to the `AttentionProcessor` as defined under
+                `self.processor` in
+                [diffusers.models.attention_processor](https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention_processor.py).
+            attention_mask ( `torch.Tensor`, *optional*):
+                An attention mask of shape `(batch, key_tokens)` is applied to `encoder_hidden_states`. If `1` the mask
+                is kept, otherwise if `0` it is discarded. Mask will be converted into a bias, which adds large
+                negative values to the attention scores corresponding to "discard" tokens.
+            encoder_attention_mask ( `torch.Tensor`, *optional*):
+                Cross-attention mask applied to `encoder_hidden_states`. Two formats supported:
+
+                    * Mask `(batch, sequence_length)` True = keep, False = discard.
+                    * Bias `(batch, 1, sequence_length)` 0 = keep, -10000 = discard.
+
+                If `ndim == 2`: will be interpreted as a mask, then converted into a bias consistent with the format
+                above. This bias will be added to the cross-attention scores.
+            skip_layer_mask ( `torch.Tensor`, *optional*):
+                A mask of shape `(num_layers, batch)` that indicates which layers to skip. `0` at position
+                `layer, batch_idx` indicates that the layer should be skipped for the corresponding batch index.
+            skip_layer_strategy ( `SkipLayerStrategy`, *optional*, defaults to `None`):
+                Controls which layers are skipped when calculating a perturbed latent for spatiotemporal guidance.
+            return_dict (`bool`, *optional*, defaults to `True`):
+                Whether or not to return a [`~models.unets.unet_2d_condition.UNet2DConditionOutput`] instead of a plain
+                tuple.
+
+        Returns:
+            If `return_dict` is True, an [`~models.transformer_2d.Transformer2DModelOutput`] is returned, otherwise a
+            `tuple` where the first element is the sample tensor.
+        """
+        # for tpu attention offload 2d token masks are used. No need to transform.
+        if not self.use_tpu_flash_attention:
+            # ensure attention_mask is a bias, and give it a singleton query_tokens dimension.
+            #   we may have done this conversion already, e.g. if we came here via UNet2DConditionModel#forward.
+            #   we can tell by counting dims; if ndim == 2: it's a mask rather than a bias.
+            # expects mask of shape:
+            #   [batch, key_tokens]
+            # adds singleton query_tokens dimension:
+            #   [batch,                    1, key_tokens]
+            # this helps to broadcast it as a bias over attention scores, which will be in one of the following shapes:
+            #   [batch,  heads, query_tokens, key_tokens] (e.g. torch sdp attn)
+            #   [batch * heads, query_tokens, key_tokens] (e.g. xformers or classic attn)
+            if attention_mask is not None and attention_mask.ndim == 2:
+                # assume that mask is expressed as:
+                #   (1 = keep,      0 = discard)
+                # convert mask into a bias that can be added to attention scores:
+                #       (keep = +0,     discard = -10000.0)
+                attention_mask = (1 - attention_mask.to(hidden_states.dtype)) * -10000.0
+                attention_mask = attention_mask.unsqueeze(1)
+
+            # convert encoder_attention_mask to a bias the same way we do for attention_mask
+            if encoder_attention_mask is not None and encoder_attention_mask.ndim == 2:
+                encoder_attention_mask = (
+                    1 - encoder_attention_mask.to(hidden_states.dtype)
+                ) * -10000.0
+                encoder_attention_mask = encoder_attention_mask.unsqueeze(1)
+
+        # 1. Input
+        hidden_states = self.patchify_proj(hidden_states)
+
+        if self.timestep_scale_multiplier:
+            timestep = self.timestep_scale_multiplier * timestep
+
+        freqs_cis = self.precompute_freqs_cis(indices_grid)
+
+        batch_size = hidden_states.shape[0]
+        timestep, embedded_timestep = self.adaln_single(
+            timestep.flatten(),
+            {"resolution": None, "aspect_ratio": None},
+            batch_size=batch_size,
+            hidden_dtype=hidden_states.dtype,
+        )
+        # Second dimension is 1 or number of tokens (if timestep_per_token)
+        timestep = timestep.view(batch_size, -1, timestep.shape[-1])
+        embedded_timestep = embedded_timestep.view(
+            batch_size, -1, embedded_timestep.shape[-1]
+        )
+
+        # 2. Blocks
+        if self.caption_projection is not None:
+            batch_size = hidden_states.shape[0]
+            encoder_hidden_states = self.caption_projection(encoder_hidden_states)
+            encoder_hidden_states = encoder_hidden_states.view(
+                batch_size, -1, hidden_states.shape[-1]
+            )
+
+        for block_idx, block in enumerate(self.transformer_blocks):
+            if self.training and self.gradient_checkpointing:
+
+                def create_custom_forward(module, return_dict=None):
+                    def custom_forward(*inputs):
+                        if return_dict is not None:
+                            return module(*inputs, return_dict=return_dict)
+                        else:
+                            return module(*inputs)
+
+                    return custom_forward
+
+                ckpt_kwargs: Dict[str, Any] = (
+                    {"use_reentrant": False} if is_torch_version(">=", "1.11.0") else {}
+                )
+                hidden_states = torch.utils.checkpoint.checkpoint(
+                    create_custom_forward(block),
+                    hidden_states,
+                    freqs_cis,
+                    attention_mask,
+                    encoder_hidden_states,
+                    encoder_attention_mask,
+                    timestep,
+                    cross_attention_kwargs,
+                    class_labels,
+                    (
+                        skip_layer_mask[block_idx]
+                        if skip_layer_mask is not None
+                        else None
+                    ),
+                    skip_layer_strategy,
+                    **ckpt_kwargs,
+                )
+            else:
+                hidden_states = block(
+                    hidden_states,
+                    freqs_cis=freqs_cis,
+                    attention_mask=attention_mask,
+                    encoder_hidden_states=encoder_hidden_states,
+                    encoder_attention_mask=encoder_attention_mask,
+                    timestep=timestep,
+                    cross_attention_kwargs=cross_attention_kwargs,
+                    class_labels=class_labels,
+                    skip_layer_mask=(
+                        skip_layer_mask[block_idx]
+                        if skip_layer_mask is not None
+                        else None
+                    ),
+                    skip_layer_strategy=skip_layer_strategy,
+                )
+
+        # 3. Output
+        scale_shift_values = (
+            self.scale_shift_table[None, None] + embedded_timestep[:, :, None]
+        )
+        shift, scale = scale_shift_values[:, :, 0], scale_shift_values[:, :, 1]
+        hidden_states = self.norm_out(hidden_states)
+        # Modulation
+        hidden_states = hidden_states * (1 + scale) + shift
+        hidden_states = self.proj_out(hidden_states)
+        if not return_dict:
+            return (hidden_states,)
+
+        return Transformer3DModelOutput(sample=hidden_states)

ltx_video/pipelines/crf_compressor.py

@@ -0,0 +1,50 @@
+import av
+import torch
+import io
+import numpy as np
+
+
+def _encode_single_frame(output_file, image_array: np.ndarray, crf):
+    container = av.open(output_file, "w", format="mp4")
+    try:
+        stream = container.add_stream(
+            "libx264", rate=1, options={"crf": str(crf), "preset": "veryfast"}
+        )
+        stream.height = image_array.shape[0]
+        stream.width = image_array.shape[1]
+        av_frame = av.VideoFrame.from_ndarray(image_array, format="rgb24").reformat(
+            format="yuv420p"
+        )
+        container.mux(stream.encode(av_frame))
+        container.mux(stream.encode())
+    finally:
+        container.close()
+
+
+def _decode_single_frame(video_file):
+    container = av.open(video_file)
+    try:
+        stream = next(s for s in container.streams if s.type == "video")
+        frame = next(container.decode(stream))
+    finally:
+        container.close()
+    return frame.to_ndarray(format="rgb24")
+
+
+def compress(image: torch.Tensor, crf=29):
+    if crf == 0:
+        return image
+
+    image_array = (
+        (image[: (image.shape[0] // 2) * 2, : (image.shape[1] // 2) * 2] * 255.0)
+        .byte()
+        .cpu()
+        .numpy()
+    )
+    with io.BytesIO() as output_file:
+        _encode_single_frame(output_file, image_array, crf)
+        video_bytes = output_file.getvalue()
+    with io.BytesIO(video_bytes) as video_file:
+        image_array = _decode_single_frame(video_file)
+    tensor = torch.tensor(image_array, dtype=image.dtype, device=image.device) / 255.0
+    return tensor

ltx_video/pipelines/pipeline_ltx_video.py

@@ -0,0 +1,1845 @@
+# Adapted from: https://github.com/huggingface/diffusers/blob/main/src/diffusers/pipelines/pixart_alpha/pipeline_pixart_alpha.py
+import copy
+import inspect
+import math
+import re
+from contextlib import nullcontext
+from dataclasses import dataclass
+from typing import Any, Callable, Dict, List, Optional, Tuple, Union
+
+import torch
+import torch.nn.functional as F
+from diffusers.image_processor import VaeImageProcessor
+from diffusers.models import AutoencoderKL
+from diffusers.pipelines.pipeline_utils import DiffusionPipeline, ImagePipelineOutput
+from diffusers.schedulers import DPMSolverMultistepScheduler
+from diffusers.utils import deprecate, logging
+from diffusers.utils.torch_utils import randn_tensor
+from einops import rearrange
+from transformers import (
+    T5EncoderModel,
+    T5Tokenizer,
+    AutoModelForCausalLM,
+    AutoProcessor,
+    AutoTokenizer,
+)
+
+from ltx_video.models.autoencoders.causal_video_autoencoder import (
+    CausalVideoAutoencoder,
+)
+from ltx_video.models.autoencoders.vae_encode import (
+    get_vae_size_scale_factor,
+    latent_to_pixel_coords,
+    vae_decode,
+    vae_encode,
+)
+from ltx_video.models.transformers.symmetric_patchifier import Patchifier
+from ltx_video.models.transformers.transformer3d import Transformer3DModel
+from ltx_video.schedulers.rf import TimestepShifter
+from ltx_video.utils.skip_layer_strategy import SkipLayerStrategy
+from ltx_video.utils.prompt_enhance_utils import generate_cinematic_prompt
+from ltx_video.models.autoencoders.latent_upsampler import LatentUpsampler
+from ltx_video.models.autoencoders.vae_encode import (
+    un_normalize_latents,
+    normalize_latents,
+)
+
+
+try:
+    import torch_xla.distributed.spmd as xs
+except ImportError:
+    xs = None
+
+logger = logging.get_logger(__name__)  # pylint: disable=invalid-name
+
+
+ASPECT_RATIO_1024_BIN = {
+    "0.25": [512.0, 2048.0],
+    "0.28": [512.0, 1856.0],
+    "0.32": [576.0, 1792.0],
+    "0.33": [576.0, 1728.0],
+    "0.35": [576.0, 1664.0],
+    "0.4": [640.0, 1600.0],
+    "0.42": [640.0, 1536.0],
+    "0.48": [704.0, 1472.0],
+    "0.5": [704.0, 1408.0],
+    "0.52": [704.0, 1344.0],
+    "0.57": [768.0, 1344.0],
+    "0.6": [768.0, 1280.0],
+    "0.68": [832.0, 1216.0],
+    "0.72": [832.0, 1152.0],
+    "0.78": [896.0, 1152.0],
+    "0.82": [896.0, 1088.0],
+    "0.88": [960.0, 1088.0],
+    "0.94": [960.0, 1024.0],
+    "1.0": [1024.0, 1024.0],
+    "1.07": [1024.0, 960.0],
+    "1.13": [1088.0, 960.0],
+    "1.21": [1088.0, 896.0],
+    "1.29": [1152.0, 896.0],
+    "1.38": [1152.0, 832.0],
+    "1.46": [1216.0, 832.0],
+    "1.67": [1280.0, 768.0],
+    "1.75": [1344.0, 768.0],
+    "2.0": [1408.0, 704.0],
+    "2.09": [1472.0, 704.0],
+    "2.4": [1536.0, 640.0],
+    "2.5": [1600.0, 640.0],
+    "3.0": [1728.0, 576.0],
+    "4.0": [2048.0, 512.0],
+}
+
+ASPECT_RATIO_512_BIN = {
+    "0.25": [256.0, 1024.0],
+    "0.28": [256.0, 928.0],
+    "0.32": [288.0, 896.0],
+    "0.33": [288.0, 864.0],
+    "0.35": [288.0, 832.0],
+    "0.4": [320.0, 800.0],
+    "0.42": [320.0, 768.0],
+    "0.48": [352.0, 736.0],
+    "0.5": [352.0, 704.0],
+    "0.52": [352.0, 672.0],
+    "0.57": [384.0, 672.0],
+    "0.6": [384.0, 640.0],
+    "0.68": [416.0, 608.0],
+    "0.72": [416.0, 576.0],
+    "0.78": [448.0, 576.0],
+    "0.82": [448.0, 544.0],
+    "0.88": [480.0, 544.0],
+    "0.94": [480.0, 512.0],
+    "1.0": [512.0, 512.0],
+    "1.07": [512.0, 480.0],
+    "1.13": [544.0, 480.0],
+    "1.21": [544.0, 448.0],
+    "1.29": [576.0, 448.0],
+    "1.38": [576.0, 416.0],
+    "1.46": [608.0, 416.0],
+    "1.67": [640.0, 384.0],
+    "1.75": [672.0, 384.0],
+    "2.0": [704.0, 352.0],
+    "2.09": [736.0, 352.0],
+    "2.4": [768.0, 320.0],
+    "2.5": [800.0, 320.0],
+    "3.0": [864.0, 288.0],
+    "4.0": [1024.0, 256.0],
+}
+
+
+# Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.retrieve_timesteps
+def retrieve_timesteps(
+    scheduler,
+    num_inference_steps: Optional[int] = None,
+    device: Optional[Union[str, torch.device]] = None,
+    timesteps: Optional[List[int]] = None,
+    skip_initial_inference_steps: int = 0,
+    skip_final_inference_steps: int = 0,
+    **kwargs,
+):
+    """
+    Calls the scheduler's `set_timesteps` method and retrieves timesteps from the scheduler after the call. Handles
+    custom timesteps. Any kwargs will be supplied to `scheduler.set_timesteps`.
+
+    Args:
+        scheduler (`SchedulerMixin`):
+            The scheduler to get timesteps from.
+        num_inference_steps (`int`):
+            The number of diffusion steps used when generating samples with a pre-trained model. If used,
+            `timesteps` must be `None`.
+        device (`str` or `torch.device`, *optional*):
+            The device to which the timesteps should be moved to. If `None`, the timesteps are not moved.
+        timesteps (`List[int]`, *optional*):
+            Custom timesteps used to support arbitrary spacing between timesteps. If `None`, then the default
+            timestep spacing strategy of the scheduler is used. If `timesteps` is passed, `num_inference_steps`
+            must be `None`.
+        max_timestep ('float', *optional*, defaults to 1.0):
+            The initial noising level for image-to-image/video-to-video. The list if timestamps will be
+            truncated to start with a timestamp greater or equal to this.
+
+    Returns:
+        `Tuple[torch.Tensor, int]`: A tuple where the first element is the timestep schedule from the scheduler and the
+        second element is the number of inference steps.
+    """
+    if timesteps is not None:
+        accepts_timesteps = "timesteps" in set(
+            inspect.signature(scheduler.set_timesteps).parameters.keys()
+        )
+        if not accepts_timesteps:
+            raise ValueError(
+                f"The current scheduler class {scheduler.__class__}'s `set_timesteps` does not support custom"
+                f" timestep schedules. Please check whether you are using the correct scheduler."
+            )
+        scheduler.set_timesteps(timesteps=timesteps, device=device, **kwargs)
+        timesteps = scheduler.timesteps
+        num_inference_steps = len(timesteps)
+    else:
+        scheduler.set_timesteps(num_inference_steps, device=device, **kwargs)
+        timesteps = scheduler.timesteps
+
+        if (
+            skip_initial_inference_steps < 0
+            or skip_final_inference_steps < 0
+            or skip_initial_inference_steps + skip_final_inference_steps
+            >= num_inference_steps
+        ):
+            raise ValueError(
+                "invalid skip inference step values: must be non-negative and the sum of skip_initial_inference_steps and skip_final_inference_steps must be less than the number of inference steps"
+            )
+
+        timesteps = timesteps[
+            skip_initial_inference_steps : len(timesteps) - skip_final_inference_steps
+        ]
+        scheduler.set_timesteps(timesteps=timesteps, device=device, **kwargs)
+        num_inference_steps = len(timesteps)
+
+    return timesteps, num_inference_steps
+
+
+@dataclass
+class ConditioningItem:
+    """
+    Defines a single frame-conditioning item - a single frame or a sequence of frames.
+
+    Attributes:
+        media_item (torch.Tensor): shape=(b, 3, f, h, w). The media item to condition on.
+        media_frame_number (int): The start-frame number of the media item in the generated video.
+        conditioning_strength (float): The strength of the conditioning (1.0 = full conditioning).
+        media_x (Optional[int]): Optional left x coordinate of the media item in the generated frame.
+        media_y (Optional[int]): Optional top y coordinate of the media item in the generated frame.
+    """
+
+    media_item: torch.Tensor
+    media_frame_number: int
+    conditioning_strength: float
+    media_x: Optional[int] = None
+    media_y: Optional[int] = None
+
+
+class LTXVideoPipeline(DiffusionPipeline):
+    r"""
+    Pipeline for text-to-image generation using LTX-Video.
+
+    This model inherits from [`DiffusionPipeline`]. Check the superclass documentation for the generic methods the
+    library implements for all the pipelines (such as downloading or saving, running on a particular device, etc.)
+
+    Args:
+        vae ([`AutoencoderKL`]):
+            Variational Auto-Encoder (VAE) Model to encode and decode images to and from latent representations.
+        text_encoder ([`T5EncoderModel`]):
+            Frozen text-encoder. This uses
+            [T5](https://huggingface.co/docs/transformers/model_doc/t5#transformers.T5EncoderModel), specifically the
+            [t5-v1_1-xxl](https://huggingface.co/PixArt-alpha/PixArt-alpha/tree/main/t5-v1_1-xxl) variant.
+        tokenizer (`T5Tokenizer`):
+            Tokenizer of class
+            [T5Tokenizer](https://huggingface.co/docs/transformers/model_doc/t5#transformers.T5Tokenizer).
+        transformer ([`Transformer2DModel`]):
+            A text conditioned `Transformer2DModel` to denoise the encoded image latents.
+        scheduler ([`SchedulerMixin`]):
+            A scheduler to be used in combination with `transformer` to denoise the encoded image latents.
+    """
+
+    bad_punct_regex = re.compile(
+        r"["
+        + "#®•©™&@·º½¾¿¡§~"
+        + r"\)"
+        + r"\("
+        + r"\]"
+        + r"\["
+        + r"\}"
+        + r"\{"
+        + r"\|"
+        + "\\"
+        + r"\/"
+        + r"\*"
+        + r"]{1,}"
+    )  # noqa
+
+    _optional_components = [
+        "tokenizer",
+        "text_encoder",
+        "prompt_enhancer_image_caption_model",
+        "prompt_enhancer_image_caption_processor",
+        "prompt_enhancer_llm_model",
+        "prompt_enhancer_llm_tokenizer",
+    ]
+    model_cpu_offload_seq = "prompt_enhancer_image_caption_model->prompt_enhancer_llm_model->text_encoder->transformer->vae"
+
+    def __init__(
+        self,
+        tokenizer: T5Tokenizer,
+        text_encoder: T5EncoderModel,
+        vae: AutoencoderKL,
+        transformer: Transformer3DModel,
+        scheduler: DPMSolverMultistepScheduler,
+        patchifier: Patchifier,
+        prompt_enhancer_image_caption_model: AutoModelForCausalLM,
+        prompt_enhancer_image_caption_processor: AutoProcessor,
+        prompt_enhancer_llm_model: AutoModelForCausalLM,
+        prompt_enhancer_llm_tokenizer: AutoTokenizer,
+        allowed_inference_steps: Optional[List[float]] = None,
+    ):
+        super().__init__()
+
+        self.register_modules(
+            tokenizer=tokenizer,
+            text_encoder=text_encoder,
+            vae=vae,
+            transformer=transformer,
+            scheduler=scheduler,
+            patchifier=patchifier,
+            prompt_enhancer_image_caption_model=prompt_enhancer_image_caption_model,
+            prompt_enhancer_image_caption_processor=prompt_enhancer_image_caption_processor,
+            prompt_enhancer_llm_model=prompt_enhancer_llm_model,
+            prompt_enhancer_llm_tokenizer=prompt_enhancer_llm_tokenizer,
+        )
+
+        self.video_scale_factor, self.vae_scale_factor, _ = get_vae_size_scale_factor(
+            self.vae
+        )
+        self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor)
+
+        self.allowed_inference_steps = allowed_inference_steps
+
+    def mask_text_embeddings(self, emb, mask):
+        if emb.shape[0] == 1:
+            keep_index = mask.sum().item()
+            return emb[:, :, :keep_index, :], keep_index
+        else:
+            masked_feature = emb * mask[:, None, :, None]
+            return masked_feature, emb.shape[2]
+
+    # Adapted from diffusers.pipelines.deepfloyd_if.pipeline_if.encode_prompt
+    def encode_prompt(
+        self,
+        prompt: Union[str, List[str]],
+        do_classifier_free_guidance: bool = True,
+        negative_prompt: str = "",
+        num_images_per_prompt: int = 1,
+        device: Optional[torch.device] = None,
+        prompt_embeds: Optional[torch.FloatTensor] = None,
+        negative_prompt_embeds: Optional[torch.FloatTensor] = None,
+        prompt_attention_mask: Optional[torch.FloatTensor] = None,
+        negative_prompt_attention_mask: Optional[torch.FloatTensor] = None,
+        text_encoder_max_tokens: int = 256,
+        **kwargs,
+    ):
+        r"""
+        Encodes the prompt into text encoder hidden states.
+
+        Args:
+            prompt (`str` or `List[str]`, *optional*):
+                prompt to be encoded
+            negative_prompt (`str` or `List[str]`, *optional*):
+                The prompt not to guide the image generation. If not defined, one has to pass `negative_prompt_embeds`
+                instead. Ignored when not using guidance (i.e., ignored if `guidance_scale` is less than `1`). For
+                This should be "".
+            do_classifier_free_guidance (`bool`, *optional*, defaults to `True`):
+                whether to use classifier free guidance or not
+            num_images_per_prompt (`int`, *optional*, defaults to 1):
+                number of images that should be generated per prompt
+            device: (`torch.device`, *optional*):
+                torch device to place the resulting embeddings on
+            prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
+                provided, text embeddings will be generated from `prompt` input argument.
+            negative_prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated negative text embeddings.
+        """
+
+        if "mask_feature" in kwargs:
+            deprecation_message = "The use of `mask_feature` is deprecated. It is no longer used in any computation and that doesn't affect the end results. It will be removed in a future version."
+            deprecate("mask_feature", "1.0.0", deprecation_message, standard_warn=False)
+
+        if device is None:
+            device = self._execution_device
+
+        if prompt is not None and isinstance(prompt, str):
+            batch_size = 1
+        elif prompt is not None and isinstance(prompt, list):
+            batch_size = len(prompt)
+        else:
+            batch_size = prompt_embeds.shape[0]
+
+        # See Section 3.1. of the paper.
+        max_length = (
+            text_encoder_max_tokens  # TPU supports only lengths multiple of 128
+        )
+        if prompt_embeds is None:
+            assert (
+                self.text_encoder is not None
+            ), "You should provide either prompt_embeds or self.text_encoder should not be None,"
+            text_enc_device = next(self.text_encoder.parameters()).device
+            prompt = self._text_preprocessing(prompt)
+            text_inputs = self.tokenizer(
+                prompt,
+                padding="max_length",
+                max_length=max_length,
+                truncation=True,
+                add_special_tokens=True,
+                return_tensors="pt",
+            )
+            text_input_ids = text_inputs.input_ids
+            untruncated_ids = self.tokenizer(
+                prompt, padding="longest", return_tensors="pt"
+            ).input_ids
+
+            if untruncated_ids.shape[-1] >= text_input_ids.shape[
+                -1
+            ] and not torch.equal(text_input_ids, untruncated_ids):
+                removed_text = self.tokenizer.batch_decode(
+                    untruncated_ids[:, max_length - 1 : -1]
+                )
+                logger.warning(
+                    "The following part of your input was truncated because CLIP can only handle sequences up to"
+                    f" {max_length} tokens: {removed_text}"
+                )
+
+            prompt_attention_mask = text_inputs.attention_mask
+            prompt_attention_mask = prompt_attention_mask.to(text_enc_device)
+            prompt_attention_mask = prompt_attention_mask.to(device)
+
+            prompt_embeds = self.text_encoder(
+                text_input_ids.to(text_enc_device), attention_mask=prompt_attention_mask
+            )
+            prompt_embeds = prompt_embeds[0]
+
+        if self.text_encoder is not None:
+            dtype = self.text_encoder.dtype
+        elif self.transformer is not None:
+            dtype = self.transformer.dtype
+        else:
+            dtype = None
+
+        prompt_embeds = prompt_embeds.to(dtype=dtype, device=device)
+
+        bs_embed, seq_len, _ = prompt_embeds.shape
+        # duplicate text embeddings and attention mask for each generation per prompt, using mps friendly method
+        prompt_embeds = prompt_embeds.repeat(1, num_images_per_prompt, 1)
+        prompt_embeds = prompt_embeds.view(
+            bs_embed * num_images_per_prompt, seq_len, -1
+        )
+        prompt_attention_mask = prompt_attention_mask.repeat(1, num_images_per_prompt)
+        prompt_attention_mask = prompt_attention_mask.view(
+            bs_embed * num_images_per_prompt, -1
+        )
+
+        # get unconditional embeddings for classifier free guidance
+        if do_classifier_free_guidance and negative_prompt_embeds is None:
+            uncond_tokens = self._text_preprocessing(negative_prompt)
+            uncond_tokens = uncond_tokens * batch_size
+            max_length = prompt_embeds.shape[1]
+            uncond_input = self.tokenizer(
+                uncond_tokens,
+                padding="max_length",
+                max_length=max_length,
+                truncation=True,
+                return_attention_mask=True,
+                add_special_tokens=True,
+                return_tensors="pt",
+            )
+            negative_prompt_attention_mask = uncond_input.attention_mask
+            negative_prompt_attention_mask = negative_prompt_attention_mask.to(
+                text_enc_device
+            )
+
+            negative_prompt_embeds = self.text_encoder(
+                uncond_input.input_ids.to(text_enc_device),
+                attention_mask=negative_prompt_attention_mask,
+            )
+            negative_prompt_embeds = negative_prompt_embeds[0]
+
+        if do_classifier_free_guidance:
+            # duplicate unconditional embeddings for each generation per prompt, using mps friendly method
+            seq_len = negative_prompt_embeds.shape[1]
+
+            negative_prompt_embeds = negative_prompt_embeds.to(
+                dtype=dtype, device=device
+            )
+
+            negative_prompt_embeds = negative_prompt_embeds.repeat(
+                1, num_images_per_prompt, 1
+            )
+            negative_prompt_embeds = negative_prompt_embeds.view(
+                batch_size * num_images_per_prompt, seq_len, -1
+            )
+
+            negative_prompt_attention_mask = negative_prompt_attention_mask.repeat(
+                1, num_images_per_prompt
+            )
+            negative_prompt_attention_mask = negative_prompt_attention_mask.view(
+                bs_embed * num_images_per_prompt, -1
+            )
+        else:
+            negative_prompt_embeds = None
+            negative_prompt_attention_mask = None
+
+        return (
+            prompt_embeds,
+            prompt_attention_mask,
+            negative_prompt_embeds,
+            negative_prompt_attention_mask,
+        )
+
+    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.prepare_extra_step_kwargs
+    def prepare_extra_step_kwargs(self, generator, eta):
+        # prepare extra kwargs for the scheduler step, since not all schedulers have the same signature
+        # eta (η) is only used with the DDIMScheduler, it will be ignored for other schedulers.
+        # eta corresponds to η in DDIM paper: https://arxiv.org/abs/2010.02502
+        # and should be between [0, 1]
+
+        accepts_eta = "eta" in set(
+            inspect.signature(self.scheduler.step).parameters.keys()
+        )
+        extra_step_kwargs = {}
+        if accepts_eta:
+            extra_step_kwargs["eta"] = eta
+
+        # check if the scheduler accepts generator
+        accepts_generator = "generator" in set(
+            inspect.signature(self.scheduler.step).parameters.keys()
+        )
+        if accepts_generator:
+            extra_step_kwargs["generator"] = generator
+        return extra_step_kwargs
+
+    def check_inputs(
+        self,
+        prompt,
+        height,
+        width,
+        negative_prompt,
+        prompt_embeds=None,
+        negative_prompt_embeds=None,
+        prompt_attention_mask=None,
+        negative_prompt_attention_mask=None,
+        enhance_prompt=False,
+    ):
+        if height % 8 != 0 or width % 8 != 0:
+            raise ValueError(
+                f"`height` and `width` have to be divisible by 8 but are {height} and {width}."
+            )
+
+        if prompt is not None and prompt_embeds is not None:
+            raise ValueError(
+                f"Cannot forward both `prompt`: {prompt} and `prompt_embeds`: {prompt_embeds}. Please make sure to"
+                " only forward one of the two."
+            )
+        elif prompt is None and prompt_embeds is None:
+            raise ValueError(
+                "Provide either `prompt` or `prompt_embeds`. Cannot leave both `prompt` and `prompt_embeds` undefined."
+            )
+        elif prompt is not None and (
+            not isinstance(prompt, str) and not isinstance(prompt, list)
+        ):
+            raise ValueError(
+                f"`prompt` has to be of type `str` or `list` but is {type(prompt)}"
+            )
+
+        if prompt is not None and negative_prompt_embeds is not None:
+            raise ValueError(
+                f"Cannot forward both `prompt`: {prompt} and `negative_prompt_embeds`:"
+                f" {negative_prompt_embeds}. Please make sure to only forward one of the two."
+            )
+
+        if negative_prompt is not None and negative_prompt_embeds is not None:
+            raise ValueError(
+                f"Cannot forward both `negative_prompt`: {negative_prompt} and `negative_prompt_embeds`:"
+                f" {negative_prompt_embeds}. Please make sure to only forward one of the two."
+            )
+
+        if prompt_embeds is not None and prompt_attention_mask is None:
+            raise ValueError(
+                "Must provide `prompt_attention_mask` when specifying `prompt_embeds`."
+            )
+
+        if (
+            negative_prompt_embeds is not None
+            and negative_prompt_attention_mask is None
+        ):
+            raise ValueError(
+                "Must provide `negative_prompt_attention_mask` when specifying `negative_prompt_embeds`."
+            )
+
+        if prompt_embeds is not None and negative_prompt_embeds is not None:
+            if prompt_embeds.shape != negative_prompt_embeds.shape:
+                raise ValueError(
+                    "`prompt_embeds` and `negative_prompt_embeds` must have the same shape when passed directly, but"
+                    f" got: `prompt_embeds` {prompt_embeds.shape} != `negative_prompt_embeds`"
+                    f" {negative_prompt_embeds.shape}."
+                )
+            if prompt_attention_mask.shape != negative_prompt_attention_mask.shape:
+                raise ValueError(
+                    "`prompt_attention_mask` and `negative_prompt_attention_mask` must have the same shape when passed directly, but"
+                    f" got: `prompt_attention_mask` {prompt_attention_mask.shape} != `negative_prompt_attention_mask`"
+                    f" {negative_prompt_attention_mask.shape}."
+                )
+
+        if enhance_prompt:
+            assert (
+                self.prompt_enhancer_image_caption_model is not None
+            ), "Image caption model must be initialized if enhance_prompt is True"
+            assert (
+                self.prompt_enhancer_image_caption_processor is not None
+            ), "Image caption processor must be initialized if enhance_prompt is True"
+            assert (
+                self.prompt_enhancer_llm_model is not None
+            ), "Text prompt enhancer model must be initialized if enhance_prompt is True"
+            assert (
+                self.prompt_enhancer_llm_tokenizer is not None
+            ), "Text prompt enhancer tokenizer must be initialized if enhance_prompt is True"
+
+    def _text_preprocessing(self, text):
+        if not isinstance(text, (tuple, list)):
+            text = [text]
+
+        def process(text: str):
+            text = text.strip()
+            return text
+
+        return [process(t) for t in text]
+
+    @staticmethod
+    def add_noise_to_image_conditioning_latents(
+        t: float,
+        init_latents: torch.Tensor,
+        latents: torch.Tensor,
+        noise_scale: float,
+        conditioning_mask: torch.Tensor,
+        generator,
+        eps=1e-6,
+    ):
+        """
+        Add timestep-dependent noise to the hard-conditioning latents.
+        This helps with motion continuity, especially when conditioned on a single frame.
+        """
+        noise = randn_tensor(
+            latents.shape,
+            generator=generator,
+            device=latents.device,
+            dtype=latents.dtype,
+        )
+        # Add noise only to hard-conditioning latents (conditioning_mask = 1.0)
+        need_to_noise = (conditioning_mask > 1.0 - eps).unsqueeze(-1)
+        noised_latents = init_latents + noise_scale * noise * (t**2)
+        latents = torch.where(need_to_noise, noised_latents, latents)
+        return latents
+
+    # Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.StableDiffusionPipeline.prepare_latents
+    def prepare_latents(
+        self,
+        latents: torch.Tensor | None,
+        media_items: torch.Tensor | None,
+        timestep: float,
+        latent_shape: torch.Size | Tuple[Any, ...],
+        dtype: torch.dtype,
+        device: torch.device,
+        generator: torch.Generator | List[torch.Generator],
+        vae_per_channel_normalize: bool = True,
+    ):
+        """
+        Prepare the initial latent tensor to be denoised.
+        The latents are either pure noise or a noised version of the encoded media items.
+        Args:
+            latents (`torch.FloatTensor` or `None`):
+                The latents to use (provided by the user) or `None` to create new latents.
+            media_items (`torch.FloatTensor` or `None`):
+                An image or video to be updated using img2img or vid2vid. The media item is encoded and noised.
+            timestep (`float`):
+                The timestep to noise the encoded media_items to.
+            latent_shape (`torch.Size`):
+                The target latent shape.
+            dtype (`torch.dtype`):
+                The target dtype.
+            device (`torch.device`):
+                The target device.
+            generator (`torch.Generator` or `List[torch.Generator]`):
+                Generator(s) to be used for the noising process.
+            vae_per_channel_normalize ('bool'):
+                When encoding the media_items, whether to normalize the latents per-channel.
+        Returns:
+            `torch.FloatTensor`: The latents to be used for the denoising process. This is a tensor of shape
+            (batch_size, num_channels, height, width).
+        """
+        if isinstance(generator, list) and len(generator) != latent_shape[0]:
+            raise ValueError(
+                f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"
+                f" size of {latent_shape[0]}. Make sure the batch size matches the length of the generators."
+            )
+
+        # Initialize the latents with the given latents or encoded media item, if provided
+        assert (
+            latents is None or media_items is None
+        ), "Cannot provide both latents and media_items. Please provide only one of the two."
+
+        assert (
+            latents is None and media_items is None or timestep < 1.0
+        ), "Input media_item or latents are provided, but they will be replaced with noise."
+
+        if media_items is not None:
+            latents = vae_encode(
+                media_items.to(dtype=self.vae.dtype, device=self.vae.device),
+                self.vae,
+                vae_per_channel_normalize=vae_per_channel_normalize,
+            )
+        if latents is not None:
+            assert (
+                latents.shape == latent_shape
+            ), f"Latents have to be of shape {latent_shape} but are {latents.shape}."
+            latents = latents.to(device=device, dtype=dtype)
+
+        # For backward compatibility, generate in the "patchified" shape and rearrange
+        b, c, f, h, w = latent_shape
+        noise = randn_tensor(
+            (b, f * h * w, c), generator=generator, device=device, dtype=dtype
+        )
+        noise = rearrange(noise, "b (f h w) c -> b c f h w", f=f, h=h, w=w)
+
+        # scale the initial noise by the standard deviation required by the scheduler
+        noise = noise * self.scheduler.init_noise_sigma
+
+        if latents is None:
+            latents = noise
+        else:
+            # Noise the latents to the required (first) timestep
+            latents = timestep * noise + (1 - timestep) * latents
+
+        return latents
+
+    @staticmethod
+    def classify_height_width_bin(
+        height: int, width: int, ratios: dict
+    ) -> Tuple[int, int]:
+        """Returns binned height and width."""
+        ar = float(height / width)
+        closest_ratio = min(ratios.keys(), key=lambda ratio: abs(float(ratio) - ar))
+        default_hw = ratios[closest_ratio]
+        return int(default_hw[0]), int(default_hw[1])
+
+    @staticmethod
+    def resize_and_crop_tensor(
+        samples: torch.Tensor, new_width: int, new_height: int
+    ) -> torch.Tensor:
+        n_frames, orig_height, orig_width = samples.shape[-3:]
+
+        # Check if resizing is needed
+        if orig_height != new_height or orig_width != new_width:
+            ratio = max(new_height / orig_height, new_width / orig_width)
+            resized_width = int(orig_width * ratio)
+            resized_height = int(orig_height * ratio)
+
+            # Resize
+            samples = LTXVideoPipeline.resize_tensor(
+                samples, resized_height, resized_width
+            )
+
+            # Center Crop
+            start_x = (resized_width - new_width) // 2
+            end_x = start_x + new_width
+            start_y = (resized_height - new_height) // 2
+            end_y = start_y + new_height
+            samples = samples[..., start_y:end_y, start_x:end_x]
+
+        return samples
+
+    @staticmethod
+    def resize_tensor(media_items, height, width):
+        n_frames = media_items.shape[2]
+        if media_items.shape[-2:] != (height, width):
+            media_items = rearrange(media_items, "b c n h w -> (b n) c h w")
+            media_items = F.interpolate(
+                media_items,
+                size=(height, width),
+                mode="bilinear",
+                align_corners=False,
+            )
+            media_items = rearrange(media_items, "(b n) c h w -> b c n h w", n=n_frames)
+        return media_items
+
+    @torch.no_grad()
+    def __call__(
+        self,
+        height: int,
+        width: int,
+        num_frames: int,
+        frame_rate: float,
+        prompt: Union[str, List[str]] = None,
+        negative_prompt: str = "",
+        num_inference_steps: int = 20,
+        skip_initial_inference_steps: int = 0,
+        skip_final_inference_steps: int = 0,
+        timesteps: List[int] = None,
+        guidance_scale: Union[float, List[float]] = 4.5,
+        cfg_star_rescale: bool = False,
+        skip_layer_strategy: Optional[SkipLayerStrategy] = None,
+        skip_block_list: Optional[Union[List[List[int]], List[int]]] = None,
+        stg_scale: Union[float, List[float]] = 1.0,
+        rescaling_scale: Union[float, List[float]] = 0.7,
+        guidance_timesteps: Optional[List[int]] = None,
+        num_images_per_prompt: Optional[int] = 1,
+        eta: float = 0.0,
+        generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
+        latents: Optional[torch.FloatTensor] = None,
+        prompt_embeds: Optional[torch.FloatTensor] = None,
+        prompt_attention_mask: Optional[torch.FloatTensor] = None,
+        negative_prompt_embeds: Optional[torch.FloatTensor] = None,
+        negative_prompt_attention_mask: Optional[torch.FloatTensor] = None,
+        output_type: Optional[str] = "pil",
+        return_dict: bool = True,
+        callback_on_step_end: Optional[Callable[[int, int, Dict], None]] = None,
+        conditioning_items: Optional[List[ConditioningItem]] = None,
+        decode_timestep: Union[List[float], float] = 0.0,
+        decode_noise_scale: Optional[List[float]] = None,
+        mixed_precision: bool = False,
+        offload_to_cpu: bool = False,
+        enhance_prompt: bool = False,
+        text_encoder_max_tokens: int = 256,
+        stochastic_sampling: bool = False,
+        media_items: Optional[torch.Tensor] = None,
+        **kwargs,
+    ) -> Union[ImagePipelineOutput, Tuple]:
+        """
+        Function invoked when calling the pipeline for generation.
+
+        Args:
+            prompt (`str` or `List[str]`, *optional*):
+                The prompt or prompts to guide the image generation. If not defined, one has to pass `prompt_embeds`.
+                instead.
+            negative_prompt (`str` or `List[str]`, *optional*):
+                The prompt or prompts not to guide the image generation. If not defined, one has to pass
+                `negative_prompt_embeds` instead. Ignored when not using guidance (i.e., ignored if `guidance_scale` is
+                less than `1`).
+            num_inference_steps (`int`, *optional*, defaults to 100):
+                The number of denoising steps. More denoising steps usually lead to a higher quality image at the
+                expense of slower inference. If `timesteps` is provided, this parameter is ignored.
+            skip_initial_inference_steps (`int`, *optional*, defaults to 0):
+                The number of initial timesteps to skip. After calculating the timesteps, this number of timesteps will
+                be removed from the beginning of the timesteps list. Meaning the highest-timesteps values will not run.
+            skip_final_inference_steps (`int`, *optional*, defaults to 0):
+                The number of final timesteps to skip. After calculating the timesteps, this number of timesteps will
+                be removed from the end of the timesteps list. Meaning the lowest-timesteps values will not run.
+            timesteps (`List[int]`, *optional*):
+                Custom timesteps to use for the denoising process. If not defined, equal spaced `num_inference_steps`
+                timesteps are used. Must be in descending order.
+            guidance_scale (`float`, *optional*, defaults to 4.5):
+                Guidance scale as defined in [Classifier-Free Diffusion Guidance](https://arxiv.org/abs/2207.12598).
+                `guidance_scale` is defined as `w` of equation 2. of [Imagen
+                Paper](https://arxiv.org/pdf/2205.11487.pdf). Guidance scale is enabled by setting `guidance_scale >
+                1`. Higher guidance scale encourages to generate images that are closely linked to the text `prompt`,
+                usually at the expense of lower image quality.
+            cfg_star_rescale (`bool`, *optional*, defaults to `False`):
+                If set to `True`, applies the CFG star rescale. Scales the negative prediction according to dot
+                product between positive and negative.
+            num_images_per_prompt (`int`, *optional*, defaults to 1):
+                The number of images to generate per prompt.
+            height (`int`, *optional*, defaults to self.unet.config.sample_size):
+                The height in pixels of the generated image.
+            width (`int`, *optional*, defaults to self.unet.config.sample_size):
+                The width in pixels of the generated image.
+            eta (`float`, *optional*, defaults to 0.0):
+                Corresponds to parameter eta (η) in the DDIM paper: https://arxiv.org/abs/2010.02502. Only applies to
+                [`schedulers.DDIMScheduler`], will be ignored for others.
+            generator (`torch.Generator` or `List[torch.Generator]`, *optional*):
+                One or a list of [torch generator(s)](https://pytorch.org/docs/stable/generated/torch.Generator.html)
+                to make generation deterministic.
+            latents (`torch.FloatTensor`, *optional*):
+                Pre-generated noisy latents, sampled from a Gaussian distribution, to be used as inputs for image
+                generation. Can be used to tweak the same generation with different prompts. If not provided, a latents
+                tensor will ge generated by sampling using the supplied random `generator`.
+            prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
+                provided, text embeddings will be generated from `prompt` input argument.
+            prompt_attention_mask (`torch.FloatTensor`, *optional*): Pre-generated attention mask for text embeddings.
+            negative_prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated negative text embeddings. This negative prompt should be "". If not
+                provided, negative_prompt_embeds will be generated from `negative_prompt` input argument.
+            negative_prompt_attention_mask (`torch.FloatTensor`, *optional*):
+                Pre-generated attention mask for negative text embeddings.
+            output_type (`str`, *optional*, defaults to `"pil"`):
+                The output format of the generate image. Choose between
+                [PIL](https://pillow.readthedocs.io/en/stable/): `PIL.Image.Image` or `np.array`.
+            return_dict (`bool`, *optional*, defaults to `True`):
+                Whether to return a [`~pipelines.stable_diffusion.IFPipelineOutput`] instead of a plain tuple.
+            callback_on_step_end (`Callable`, *optional*):
+                A function that calls at the end of each denoising steps during the inference. The function is called
+                with the following arguments: `callback_on_step_end(self: DiffusionPipeline, step: int, timestep: int,
+                callback_kwargs: Dict)`. `callback_kwargs` will include a list of all tensors as specified by
+                `callback_on_step_end_tensor_inputs`.
+            use_resolution_binning (`bool` defaults to `True`):
+                If set to `True`, the requested height and width are first mapped to the closest resolutions using
+                `ASPECT_RATIO_1024_BIN`. After the produced latents are decoded into images, they are resized back to
+                the requested resolution. Useful for generating non-square images.
+            enhance_prompt (`bool`, *optional*, defaults to `False`):
+                If set to `True`, the prompt is enhanced using a LLM model.
+            text_encoder_max_tokens (`int`, *optional*, defaults to `256`):
+                The maximum number of tokens to use for the text encoder.
+            stochastic_sampling (`bool`, *optional*, defaults to `False`):
+                If set to `True`, the sampling is stochastic. If set to `False`, the sampling is deterministic.
+            media_items ('torch.Tensor', *optional*):
+                The input media item used for image-to-image / video-to-video.
+        Examples:
+
+        Returns:
+            [`~pipelines.ImagePipelineOutput`] or `tuple`:
+                If `return_dict` is `True`, [`~pipelines.ImagePipelineOutput`] is returned, otherwise a `tuple` is
+                returned where the first element is a list with the generated images
+        """
+        if "mask_feature" in kwargs:
+            deprecation_message = "The use of `mask_feature` is deprecated. It is no longer used in any computation and that doesn't affect the end results. It will be removed in a future version."
+            deprecate("mask_feature", "1.0.0", deprecation_message, standard_warn=False)
+
+        is_video = kwargs.get("is_video", False)
+        self.check_inputs(
+            prompt,
+            height,
+            width,
+            negative_prompt,
+            prompt_embeds,
+            negative_prompt_embeds,
+            prompt_attention_mask,
+            negative_prompt_attention_mask,
+        )
+
+        # 2. Default height and width to transformer
+        if prompt is not None and isinstance(prompt, str):
+            batch_size = 1
+        elif prompt is not None and isinstance(prompt, list):
+            batch_size = len(prompt)
+        else:
+            batch_size = prompt_embeds.shape[0]
+
+        device = self._execution_device
+
+        self.video_scale_factor = self.video_scale_factor if is_video else 1
+        vae_per_channel_normalize = kwargs.get("vae_per_channel_normalize", True)
+        image_cond_noise_scale = kwargs.get("image_cond_noise_scale", 0.0)
+
+        latent_height = height // self.vae_scale_factor
+        latent_width = width // self.vae_scale_factor
+        latent_num_frames = num_frames // self.video_scale_factor
+        if isinstance(self.vae, CausalVideoAutoencoder) and is_video:
+            latent_num_frames += 1
+        latent_shape = (
+            batch_size * num_images_per_prompt,
+            self.transformer.config.in_channels,
+            latent_num_frames,
+            latent_height,
+            latent_width,
+        )
+
+        # Prepare the list of denoising time-steps
+
+        retrieve_timesteps_kwargs = {}
+        if isinstance(self.scheduler, TimestepShifter):
+            retrieve_timesteps_kwargs["samples_shape"] = latent_shape
+
+        assert (
+            skip_initial_inference_steps == 0
+            or latents is not None
+            or media_items is not None
+        ), (
+            f"skip_initial_inference_steps ({skip_initial_inference_steps}) is used for image-to-image/video-to-video - "
+            "media_item or latents should be provided."
+        )
+
+        timesteps, num_inference_steps = retrieve_timesteps(
+            self.scheduler,
+            num_inference_steps,
+            device,
+            timesteps,
+            skip_initial_inference_steps=skip_initial_inference_steps,
+            skip_final_inference_steps=skip_final_inference_steps,
+            **retrieve_timesteps_kwargs,
+        )
+
+        if self.allowed_inference_steps is not None:
+            for timestep in [round(x, 4) for x in timesteps.tolist()]:
+                assert (
+                    timestep in self.allowed_inference_steps
+                ), f"Invalid inference timestep {timestep}. Allowed timesteps are {self.allowed_inference_steps}."
+
+        if guidance_timesteps:
+            guidance_mapping = []
+            for timestep in timesteps:
+                indices = [
+                    i for i, val in enumerate(guidance_timesteps) if val <= timestep
+                ]
+                # assert len(indices) > 0, f"No guidance timestep found for {timestep}"
+                guidance_mapping.append(
+                    indices[0] if len(indices) > 0 else (len(guidance_timesteps) - 1)
+                )
+
+        # here `guidance_scale` is defined analog to the guidance weight `w` of equation (2)
+        # of the Imagen paper: https://arxiv.org/pdf/2205.11487.pdf . `guidance_scale = 1`
+        # corresponds to doing no classifier free guidance.
+        if not isinstance(guidance_scale, List):
+            guidance_scale = [guidance_scale] * len(timesteps)
+        else:
+            guidance_scale = [
+                guidance_scale[guidance_mapping[i]] for i in range(len(timesteps))
+            ]
+
+        # For simplicity, we are using a constant num_conds for all timesteps, so we need to zero
+        # out cases where the guidance scale should not be applied.
+        guidance_scale = [x if x > 1.0 else 0.0 for x in guidance_scale]
+
+        if not isinstance(stg_scale, List):
+            stg_scale = [stg_scale] * len(timesteps)
+        else:
+            stg_scale = [stg_scale[guidance_mapping[i]] for i in range(len(timesteps))]
+
+        if not isinstance(rescaling_scale, List):
+            rescaling_scale = [rescaling_scale] * len(timesteps)
+        else:
+            rescaling_scale = [
+                rescaling_scale[guidance_mapping[i]] for i in range(len(timesteps))
+            ]
+
+        do_classifier_free_guidance = any(x > 1.0 for x in guidance_scale)
+        do_spatio_temporal_guidance = any(x > 0.0 for x in stg_scale)
+        do_rescaling = any(x != 1.0 for x in rescaling_scale)
+
+        num_conds = 1
+        if do_classifier_free_guidance:
+            num_conds += 1
+        if do_spatio_temporal_guidance:
+            num_conds += 1
+
+        # Normalize skip_block_list to always be None or a list of lists matching timesteps
+        if skip_block_list is not None:
+            # Convert single list to list of lists if needed
+            if len(skip_block_list) == 0 or not isinstance(skip_block_list[0], list):
+                skip_block_list = [skip_block_list] * len(timesteps)
+            else:
+                new_skip_block_list = []
+                for i, timestep in enumerate(timesteps):
+                    new_skip_block_list.append(skip_block_list[guidance_mapping[i]])
+                skip_block_list = new_skip_block_list
+
+        # Prepare skip layer masks
+        skip_layer_masks: Optional[List[torch.Tensor]] = None
+        if do_spatio_temporal_guidance:
+            if skip_block_list is not None:
+                skip_layer_masks = [
+                    self.transformer.create_skip_layer_mask(
+                        batch_size, num_conds, num_conds - 1, skip_blocks
+                    )
+                    for skip_blocks in skip_block_list
+                ]
+
+        if enhance_prompt:
+            self.prompt_enhancer_image_caption_model = (
+                self.prompt_enhancer_image_caption_model.to(self._execution_device)
+            )
+            self.prompt_enhancer_llm_model = self.prompt_enhancer_llm_model.to(
+                self._execution_device
+            )
+
+            prompt = generate_cinematic_prompt(
+                self.prompt_enhancer_image_caption_model,
+                self.prompt_enhancer_image_caption_processor,
+                self.prompt_enhancer_llm_model,
+                self.prompt_enhancer_llm_tokenizer,
+                prompt,
+                conditioning_items,
+                max_new_tokens=text_encoder_max_tokens,
+            )
+
+        # 3. Encode input prompt
+        if self.text_encoder is not None:
+            self.text_encoder = self.text_encoder.to(self._execution_device)
+
+        (
+            prompt_embeds,
+            prompt_attention_mask,
+            negative_prompt_embeds,
+            negative_prompt_attention_mask,
+        ) = self.encode_prompt(
+            prompt,
+            do_classifier_free_guidance,
+            negative_prompt=negative_prompt,
+            num_images_per_prompt=num_images_per_prompt,
+            device=device,
+            prompt_embeds=prompt_embeds,
+            negative_prompt_embeds=negative_prompt_embeds,
+            prompt_attention_mask=prompt_attention_mask,
+            negative_prompt_attention_mask=negative_prompt_attention_mask,
+            text_encoder_max_tokens=text_encoder_max_tokens,
+        )
+
+        if offload_to_cpu and self.text_encoder is not None:
+            self.text_encoder = self.text_encoder.cpu()
+
+        self.transformer = self.transformer.to(self._execution_device)
+
+        prompt_embeds_batch = prompt_embeds
+        prompt_attention_mask_batch = prompt_attention_mask
+        if do_classifier_free_guidance:
+            prompt_embeds_batch = torch.cat(
+                [negative_prompt_embeds, prompt_embeds], dim=0
+            )
+            prompt_attention_mask_batch = torch.cat(
+                [negative_prompt_attention_mask, prompt_attention_mask], dim=0
+            )
+        if do_spatio_temporal_guidance:
+            prompt_embeds_batch = torch.cat([prompt_embeds_batch, prompt_embeds], dim=0)
+            prompt_attention_mask_batch = torch.cat(
+                [
+                    prompt_attention_mask_batch,
+                    prompt_attention_mask,
+                ],
+                dim=0,
+            )
+
+        # 4. Prepare the initial latents using the provided media and conditioning items
+
+        # Prepare the initial latents tensor, shape = (b, c, f, h, w)
+        latents = self.prepare_latents(
+            latents=latents,
+            media_items=media_items,
+            timestep=timesteps[0],
+            latent_shape=latent_shape,
+            dtype=prompt_embeds_batch.dtype,
+            device=device,
+            generator=generator,
+            vae_per_channel_normalize=vae_per_channel_normalize,
+        )
+
+        # Update the latents with the conditioning items and patchify them into (b, n, c)
+        latents, pixel_coords, conditioning_mask, num_cond_latents = (
+            self.prepare_conditioning(
+                conditioning_items=conditioning_items,
+                init_latents=latents,
+                num_frames=num_frames,
+                height=height,
+                width=width,
+                vae_per_channel_normalize=vae_per_channel_normalize,
+                generator=generator,
+            )
+        )
+        init_latents = latents.clone()  # Used for image_cond_noise_update
+
+        pixel_coords = torch.cat([pixel_coords] * num_conds)
+        orig_conditioning_mask = conditioning_mask
+        if conditioning_mask is not None and is_video:
+            assert num_images_per_prompt == 1
+            conditioning_mask = torch.cat([conditioning_mask] * num_conds)
+        fractional_coords = pixel_coords.to(torch.float32)
+        fractional_coords[:, 0] = fractional_coords[:, 0] * (1.0 / frame_rate)
+
+        # 6. Prepare extra step kwargs. TODO: Logic should ideally just be moved out of the pipeline
+        extra_step_kwargs = self.prepare_extra_step_kwargs(generator, eta)
+
+        # 7. Denoising loop
+        num_warmup_steps = max(
+            len(timesteps) - num_inference_steps * self.scheduler.order, 0
+        )
+
+        with self.progress_bar(total=num_inference_steps) as progress_bar:
+            for i, t in enumerate(timesteps):
+                if conditioning_mask is not None and image_cond_noise_scale > 0.0:
+                    latents = self.add_noise_to_image_conditioning_latents(
+                        t,
+                        init_latents,
+                        latents,
+                        image_cond_noise_scale,
+                        orig_conditioning_mask,
+                        generator,
+                    )
+
+                latent_model_input = (
+                    torch.cat([latents] * num_conds) if num_conds > 1 else latents
+                )
+                latent_model_input = self.scheduler.scale_model_input(
+                    latent_model_input, t
+                )
+
+                current_timestep = t
+                if not torch.is_tensor(current_timestep):
+                    # TODO: this requires sync between CPU and GPU. So try to pass timesteps as tensors if you can
+                    # This would be a good case for the `match` statement (Python 3.10+)
+                    is_mps = latent_model_input.device.type == "mps"
+                    if isinstance(current_timestep, float):
+                        dtype = torch.float32 if is_mps else torch.float64
+                    else:
+                        dtype = torch.int32 if is_mps else torch.int64
+                    current_timestep = torch.tensor(
+                        [current_timestep],
+                        dtype=dtype,
+                        device=latent_model_input.device,
+                    )
+                elif len(current_timestep.shape) == 0:
+                    current_timestep = current_timestep[None].to(
+                        latent_model_input.device
+                    )
+                # broadcast to batch dimension in a way that's compatible with ONNX/Core ML
+                current_timestep = current_timestep.expand(
+                    latent_model_input.shape[0]
+                ).unsqueeze(-1)
+
+                if conditioning_mask is not None:
+                    # Conditioning latents have an initial timestep and noising level of (1.0 - conditioning_mask)
+                    # and will start to be denoised when the current timestep is lower than their conditioning timestep.
+                    current_timestep = torch.min(
+                        current_timestep, 1.0 - conditioning_mask
+                    )
+
+                # Choose the appropriate context manager based on `mixed_precision`
+                if mixed_precision:
+                    context_manager = torch.autocast(device.type, dtype=torch.bfloat16)
+                else:
+                    context_manager = nullcontext()  # Dummy context manager
+
+                # predict noise model_output
+                with context_manager:
+                    noise_pred = self.transformer(
+                        latent_model_input.to(self.transformer.dtype),
+                        indices_grid=fractional_coords,
+                        encoder_hidden_states=prompt_embeds_batch.to(
+                            self.transformer.dtype
+                        ),
+                        encoder_attention_mask=prompt_attention_mask_batch,
+                        timestep=current_timestep,
+                        skip_layer_mask=(
+                            skip_layer_masks[i]
+                            if skip_layer_masks is not None
+                            else None
+                        ),
+                        skip_layer_strategy=skip_layer_strategy,
+                        return_dict=False,
+                    )[0]
+
+                # perform guidance
+                if do_spatio_temporal_guidance:
+                    noise_pred_text, noise_pred_text_perturb = noise_pred.chunk(
+                        num_conds
+                    )[-2:]
+                if do_classifier_free_guidance:
+                    noise_pred_uncond, noise_pred_text = noise_pred.chunk(num_conds)[:2]
+
+                    if cfg_star_rescale:
+                        # Rescales the unconditional noise prediction using the projection of the conditional prediction onto it:
+                        # α = (⟨ε_text, ε_uncond⟩ / ||ε_uncond||²), then ε_uncond ← α * ε_uncond
+                        # where ε_text is the conditional noise prediction and ε_uncond is the unconditional one.
+                        positive_flat = noise_pred_text.view(batch_size, -1)
+                        negative_flat = noise_pred_uncond.view(batch_size, -1)
+                        dot_product = torch.sum(
+                            positive_flat * negative_flat, dim=1, keepdim=True
+                        )
+                        squared_norm = (
+                            torch.sum(negative_flat**2, dim=1, keepdim=True) + 1e-8
+                        )
+                        alpha = dot_product / squared_norm
+                        noise_pred_uncond = alpha * noise_pred_uncond
+
+                    noise_pred = noise_pred_uncond + guidance_scale[i] * (
+                        noise_pred_text - noise_pred_uncond
+                    )
+                elif do_spatio_temporal_guidance:
+                    noise_pred = noise_pred_text
+                if do_spatio_temporal_guidance:
+                    noise_pred = noise_pred + stg_scale[i] * (
+                        noise_pred_text - noise_pred_text_perturb
+                    )
+                    if do_rescaling and stg_scale[i] > 0.0:
+                        noise_pred_text_std = noise_pred_text.view(batch_size, -1).std(
+                            dim=1, keepdim=True
+                        )
+                        noise_pred_std = noise_pred.view(batch_size, -1).std(
+                            dim=1, keepdim=True
+                        )
+
+                        factor = noise_pred_text_std / noise_pred_std
+                        factor = rescaling_scale[i] * factor + (1 - rescaling_scale[i])
+
+                        noise_pred = noise_pred * factor.view(batch_size, 1, 1)
+
+                current_timestep = current_timestep[:1]
+                # learned sigma
+                if (
+                    self.transformer.config.out_channels // 2
+                    == self.transformer.config.in_channels
+                ):
+                    noise_pred = noise_pred.chunk(2, dim=1)[0]
+
+                # compute previous image: x_t -> x_t-1
+                latents = self.denoising_step(
+                    latents,
+                    noise_pred,
+                    current_timestep,
+                    orig_conditioning_mask,
+                    t,
+                    extra_step_kwargs,
+                    stochastic_sampling=stochastic_sampling,
+                )
+
+                # call the callback, if provided
+                if i == len(timesteps) - 1 or (
+                    (i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0
+                ):
+                    progress_bar.update()
+
+                if callback_on_step_end is not None:
+                    callback_on_step_end(self, i, t, {})
+
+        if offload_to_cpu:
+            self.transformer = self.transformer.cpu()
+            if self._execution_device == "cuda":
+                torch.cuda.empty_cache()
+
+        # Remove the added conditioning latents
+        latents = latents[:, num_cond_latents:]
+
+        latents = self.patchifier.unpatchify(
+            latents=latents,
+            output_height=latent_height,
+            output_width=latent_width,
+            out_channels=self.transformer.in_channels
+            // math.prod(self.patchifier.patch_size),
+        )
+        if output_type != "latent":
+            if self.vae.decoder.timestep_conditioning:
+                noise = torch.randn_like(latents)
+                if not isinstance(decode_timestep, list):
+                    decode_timestep = [decode_timestep] * latents.shape[0]
+                if decode_noise_scale is None:
+                    decode_noise_scale = decode_timestep
+                elif not isinstance(decode_noise_scale, list):
+                    decode_noise_scale = [decode_noise_scale] * latents.shape[0]
+
+                decode_timestep = torch.tensor(decode_timestep).to(latents.device)
+                decode_noise_scale = torch.tensor(decode_noise_scale).to(
+                    latents.device
+                )[:, None, None, None, None]
+                latents = (
+                    latents * (1 - decode_noise_scale) + noise * decode_noise_scale
+                )
+            else:
+                decode_timestep = None
+            image = vae_decode(
+                latents,
+                self.vae,
+                is_video,
+                vae_per_channel_normalize=kwargs["vae_per_channel_normalize"],
+                timestep=decode_timestep,
+            )
+
+            image = self.image_processor.postprocess(image, output_type=output_type)
+
+        else:
+            image = latents
+
+        # Offload all models
+        self.maybe_free_model_hooks()
+
+        if not return_dict:
+            return (image,)
+
+        return ImagePipelineOutput(images=image)
+
+    def denoising_step(
+        self,
+        latents: torch.Tensor,
+        noise_pred: torch.Tensor,
+        current_timestep: torch.Tensor,
+        conditioning_mask: torch.Tensor,
+        t: float,
+        extra_step_kwargs,
+        t_eps=1e-6,
+        stochastic_sampling=False,
+    ):
+        """
+        Perform the denoising step for the required tokens, based on the current timestep and
+        conditioning mask:
+        Conditioning latents have an initial timestep and noising level of (1.0 - conditioning_mask)
+        and will start to be denoised when the current timestep is equal or lower than their
+        conditioning timestep.
+        (hard-conditioning latents with conditioning_mask = 1.0 are never denoised)
+        """
+        # Denoise the latents using the scheduler
+        denoised_latents = self.scheduler.step(
+            noise_pred,
+            t if current_timestep is None else current_timestep,
+            latents,
+            **extra_step_kwargs,
+            return_dict=False,
+            stochastic_sampling=stochastic_sampling,
+        )[0]
+
+        if conditioning_mask is None:
+            return denoised_latents
+
+        tokens_to_denoise_mask = (t - t_eps < (1.0 - conditioning_mask)).unsqueeze(-1)
+        return torch.where(tokens_to_denoise_mask, denoised_latents, latents)
+
+    def prepare_conditioning(
+        self,
+        conditioning_items: Optional[List[ConditioningItem]],
+        init_latents: torch.Tensor,
+        num_frames: int,
+        height: int,
+        width: int,
+        vae_per_channel_normalize: bool = False,
+        generator=None,
+    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, int]:
+        """
+        Prepare conditioning tokens based on the provided conditioning items.
+
+        This method encodes provided conditioning items (video frames or single frames) into latents
+        and integrates them with the initial latent tensor. It also calculates corresponding pixel
+        coordinates, a mask indicating the influence of conditioning latents, and the total number of
+        conditioning latents.
+
+        Args:
+            conditioning_items (Optional[List[ConditioningItem]]): A list of ConditioningItem objects.
+            init_latents (torch.Tensor): The initial latent tensor of shape (b, c, f_l, h_l, w_l), where
+                `f_l` is the number of latent frames, and `h_l` and `w_l` are latent spatial dimensions.
+            num_frames, height, width: The dimensions of the generated video.
+            vae_per_channel_normalize (bool, optional): Whether to normalize channels during VAE encoding.
+                Defaults to `False`.
+            generator: The random generator
+
+        Returns:
+            Tuple[torch.Tensor, torch.Tensor, torch.Tensor, int]:
+                - `init_latents` (torch.Tensor): The updated latent tensor including conditioning latents,
+                  patchified into (b, n, c) shape.
+                - `init_pixel_coords` (torch.Tensor): The pixel coordinates corresponding to the updated
+                  latent tensor.
+                - `conditioning_mask` (torch.Tensor): A mask indicating the conditioning-strength of each
+                  latent token.
+                - `num_cond_latents` (int): The total number of latent tokens added from conditioning items.
+
+        Raises:
+            AssertionError: If input shapes, dimensions, or conditions for applying conditioning are invalid.
+        """
+        assert isinstance(self.vae, CausalVideoAutoencoder)
+
+        if conditioning_items:
+            batch_size, _, num_latent_frames = init_latents.shape[:3]
+
+            init_conditioning_mask = torch.zeros(
+                init_latents[:, 0, :, :, :].shape,
+                dtype=torch.float32,
+                device=init_latents.device,
+            )
+
+            extra_conditioning_latents = []
+            extra_conditioning_pixel_coords = []
+            extra_conditioning_mask = []
+            extra_conditioning_num_latents = 0  # Number of extra conditioning latents added (should be removed before decoding)
+
+            # Process each conditioning item
+            for conditioning_item in conditioning_items:
+                conditioning_item = self._resize_conditioning_item(
+                    conditioning_item, height, width
+                )
+                media_item = conditioning_item.media_item
+                media_frame_number = conditioning_item.media_frame_number
+                strength = conditioning_item.conditioning_strength
+                assert media_item.ndim == 5  # (b, c, f, h, w)
+                b, c, n_frames, h, w = media_item.shape
+                assert (
+                    height == h and width == w
+                ) or media_frame_number == 0, f"Dimensions do not match: {height}x{width} != {h}x{w} - allowed only when media_frame_number == 0"
+                assert n_frames % 8 == 1
+                assert (
+                    media_frame_number >= 0
+                    and media_frame_number + n_frames <= num_frames
+                )
+
+                # Encode the provided conditioning media item
+                media_item_latents = vae_encode(
+                    media_item.to(dtype=self.vae.dtype, device=self.vae.device),
+                    self.vae,
+                    vae_per_channel_normalize=vae_per_channel_normalize,
+                ).to(dtype=init_latents.dtype)
+
+                # Handle the different conditioning cases
+                if media_frame_number == 0:
+                    # Get the target spatial position of the latent conditioning item
+                    media_item_latents, l_x, l_y = self._get_latent_spatial_position(
+                        media_item_latents,
+                        conditioning_item,
+                        height,
+                        width,
+                        strip_latent_border=True,
+                    )
+                    b, c_l, f_l, h_l, w_l = media_item_latents.shape
+
+                    # First frame or sequence - just update the initial noise latents and the mask
+                    init_latents[:, :, :f_l, l_y : l_y + h_l, l_x : l_x + w_l] = (
+                        torch.lerp(
+                            init_latents[:, :, :f_l, l_y : l_y + h_l, l_x : l_x + w_l],
+                            media_item_latents,
+                            strength,
+                        )
+                    )
+                    init_conditioning_mask[
+                        :, :f_l, l_y : l_y + h_l, l_x : l_x + w_l
+                    ] = strength
+                else:
+                    # Non-first frame or sequence
+                    if n_frames > 1:
+                        # Handle non-first sequence.
+                        # Encoded latents are either fully consumed, or the prefix is handled separately below.
+                        (
+                            init_latents,
+                            init_conditioning_mask,
+                            media_item_latents,
+                        ) = self._handle_non_first_conditioning_sequence(
+                            init_latents,
+                            init_conditioning_mask,
+                            media_item_latents,
+                            media_frame_number,
+                            strength,
+                        )
+
+                    # Single frame or sequence-prefix latents
+                    if media_item_latents is not None:
+                        noise = randn_tensor(
+                            media_item_latents.shape,
+                            generator=generator,
+                            device=media_item_latents.device,
+                            dtype=media_item_latents.dtype,
+                        )
+
+                        media_item_latents = torch.lerp(
+                            noise, media_item_latents, strength
+                        )
+
+                        # Patchify the extra conditioning latents and calculate their pixel coordinates
+                        media_item_latents, latent_coords = self.patchifier.patchify(
+                            latents=media_item_latents
+                        )
+                        pixel_coords = latent_to_pixel_coords(
+                            latent_coords,
+                            self.vae,
+                            causal_fix=self.transformer.config.causal_temporal_positioning,
+                        )
+
+                        # Update the frame numbers to match the target frame number
+                        pixel_coords[:, 0] += media_frame_number
+                        extra_conditioning_num_latents += media_item_latents.shape[1]
+
+                        conditioning_mask = torch.full(
+                            media_item_latents.shape[:2],
+                            strength,
+                            dtype=torch.float32,
+                            device=init_latents.device,
+                        )
+
+                        extra_conditioning_latents.append(media_item_latents)
+                        extra_conditioning_pixel_coords.append(pixel_coords)
+                        extra_conditioning_mask.append(conditioning_mask)
+
+        # Patchify the updated latents and calculate their pixel coordinates
+        init_latents, init_latent_coords = self.patchifier.patchify(
+            latents=init_latents
+        )
+        init_pixel_coords = latent_to_pixel_coords(
+            init_latent_coords,
+            self.vae,
+            causal_fix=self.transformer.config.causal_temporal_positioning,
+        )
+
+        if not conditioning_items:
+            return init_latents, init_pixel_coords, None, 0
+
+        init_conditioning_mask, _ = self.patchifier.patchify(
+            latents=init_conditioning_mask.unsqueeze(1)
+        )
+        init_conditioning_mask = init_conditioning_mask.squeeze(-1)
+
+        if extra_conditioning_latents:
+            # Stack the extra conditioning latents, pixel coordinates and mask
+            init_latents = torch.cat([*extra_conditioning_latents, init_latents], dim=1)
+            init_pixel_coords = torch.cat(
+                [*extra_conditioning_pixel_coords, init_pixel_coords], dim=2
+            )
+            init_conditioning_mask = torch.cat(
+                [*extra_conditioning_mask, init_conditioning_mask], dim=1
+            )
+
+            if self.transformer.use_tpu_flash_attention:
+                # When flash attention is used, keep the original number of tokens by removing
+                #   tokens from the end.
+                init_latents = init_latents[:, :-extra_conditioning_num_latents]
+                init_pixel_coords = init_pixel_coords[
+                    :, :, :-extra_conditioning_num_latents
+                ]
+                init_conditioning_mask = init_conditioning_mask[
+                    :, :-extra_conditioning_num_latents
+                ]
+
+        return (
+            init_latents,
+            init_pixel_coords,
+            init_conditioning_mask,
+            extra_conditioning_num_latents,
+        )
+
+    @staticmethod
+    def _resize_conditioning_item(
+        conditioning_item: ConditioningItem,
+        height: int,
+        width: int,
+    ):
+        if conditioning_item.media_x or conditioning_item.media_y:
+            raise ValueError(
+                "Provide media_item in the target size for spatial conditioning."
+            )
+        new_conditioning_item = copy.copy(conditioning_item)
+        new_conditioning_item.media_item = LTXVideoPipeline.resize_tensor(
+            conditioning_item.media_item, height, width
+        )
+        return new_conditioning_item
+
+    def _get_latent_spatial_position(
+        self,
+        latents: torch.Tensor,
+        conditioning_item: ConditioningItem,
+        height: int,
+        width: int,
+        strip_latent_border,
+    ):
+        """
+        Get the spatial position of the conditioning item in the latent space.
+        If requested, strip the conditioning latent borders that do not align with target borders.
+        (border latents look different then other latents and might confuse the model)
+        """
+        scale = self.vae_scale_factor
+        h, w = conditioning_item.media_item.shape[-2:]
+        assert (
+            h <= height and w <= width
+        ), f"Conditioning item size {h}x{w} is larger than target size {height}x{width}"
+        assert h % scale == 0 and w % scale == 0
+
+        # Compute the start and end spatial positions of the media item
+        x_start, y_start = conditioning_item.media_x, conditioning_item.media_y
+        x_start = (width - w) // 2 if x_start is None else x_start
+        y_start = (height - h) // 2 if y_start is None else y_start
+        x_end, y_end = x_start + w, y_start + h
+        assert (
+            x_end <= width and y_end <= height
+        ), f"Conditioning item {x_start}:{x_end}x{y_start}:{y_end} is out of bounds for target size {width}x{height}"
+
+        if strip_latent_border:
+            # Strip one latent from left/right and/or top/bottom, update x, y accordingly
+            if x_start > 0:
+                x_start += scale
+                latents = latents[:, :, :, :, 1:]
+
+            if y_start > 0:
+                y_start += scale
+                latents = latents[:, :, :, 1:, :]
+
+            if x_end < width:
+                latents = latents[:, :, :, :, :-1]
+
+            if y_end < height:
+                latents = latents[:, :, :, :-1, :]
+
+        return latents, x_start // scale, y_start // scale
+
+    @staticmethod
+    def _handle_non_first_conditioning_sequence(
+        init_latents: torch.Tensor,
+        init_conditioning_mask: torch.Tensor,
+        latents: torch.Tensor,
+        media_frame_number: int,
+        strength: float,
+        num_prefix_latent_frames: int = 2,
+        prefix_latents_mode: str = "concat",
+        prefix_soft_conditioning_strength: float = 0.15,
+    ):
+        """
+        Special handling for a conditioning sequence that does not start on the first frame.
+        The special handling is required to allow a short encoded video to be used as middle
+        (or last) sequence in a longer video.
+        Args:
+            init_latents (torch.Tensor): The initial noise latents to be updated.
+            init_conditioning_mask (torch.Tensor): The initial conditioning mask to be updated.
+            latents (torch.Tensor): The encoded conditioning item.
+            media_frame_number (int): The target frame number of the first frame in the conditioning sequence.
+            strength (float): The conditioning strength for the conditioning latents.
+            num_prefix_latent_frames (int, optional): The length of the sequence prefix, to be handled
+                separately. Defaults to 2.
+            prefix_latents_mode (str, optional): Special treatment for prefix (boundary) latents.
+                - "drop": Drop the prefix latents.
+                - "soft": Use the prefix latents, but with soft-conditioning
+                - "concat": Add the prefix latents as extra tokens (like single frames)
+            prefix_soft_conditioning_strength (float, optional): The strength of the soft-conditioning for
+                the prefix latents, relevant if `prefix_latents_mode` is "soft". Defaults to 0.1.
+
+        """
+        f_l = latents.shape[2]
+        f_l_p = num_prefix_latent_frames
+        assert f_l >= f_l_p
+        assert media_frame_number % 8 == 0
+        if f_l > f_l_p:
+            # Insert the conditioning latents **excluding the prefix** into the sequence
+            f_l_start = media_frame_number // 8 + f_l_p
+            f_l_end = f_l_start + f_l - f_l_p
+            init_latents[:, :, f_l_start:f_l_end] = torch.lerp(
+                init_latents[:, :, f_l_start:f_l_end],
+                latents[:, :, f_l_p:],
+                strength,
+            )
+            # Mark these latent frames as conditioning latents
+            init_conditioning_mask[:, f_l_start:f_l_end] = strength
+
+        # Handle the prefix-latents
+        if prefix_latents_mode == "soft":
+            if f_l_p > 1:
+                # Drop the first (single-frame) latent and soft-condition the remaining prefix
+                f_l_start = media_frame_number // 8 + 1
+                f_l_end = f_l_start + f_l_p - 1
+                strength = min(prefix_soft_conditioning_strength, strength)
+                init_latents[:, :, f_l_start:f_l_end] = torch.lerp(
+                    init_latents[:, :, f_l_start:f_l_end],
+                    latents[:, :, 1:f_l_p],
+                    strength,
+                )
+                # Mark these latent frames as conditioning latents
+                init_conditioning_mask[:, f_l_start:f_l_end] = strength
+            latents = None  # No more latents to handle
+        elif prefix_latents_mode == "drop":
+            # Drop the prefix latents
+            latents = None
+        elif prefix_latents_mode == "concat":
+            # Pass-on the prefix latents to be handled as extra conditioning frames
+            latents = latents[:, :, :f_l_p]
+        else:
+            raise ValueError(f"Invalid prefix_latents_mode: {prefix_latents_mode}")
+        return (
+            init_latents,
+            init_conditioning_mask,
+            latents,
+        )
+
+    def trim_conditioning_sequence(
+        self, start_frame: int, sequence_num_frames: int, target_num_frames: int
+    ):
+        """
+        Trim a conditioning sequence to the allowed number of frames.
+
+        Args:
+            start_frame (int): The target frame number of the first frame in the sequence.
+            sequence_num_frames (int): The number of frames in the sequence.
+            target_num_frames (int): The target number of frames in the generated video.
+
+        Returns:
+            int: updated sequence length
+        """
+        scale_factor = self.video_scale_factor
+        num_frames = min(sequence_num_frames, target_num_frames - start_frame)
+        # Trim down to a multiple of temporal_scale_factor frames plus 1
+        num_frames = (num_frames - 1) // scale_factor * scale_factor + 1
+        return num_frames
+
+
+def adain_filter_latent(
+    latents: torch.Tensor, reference_latents: torch.Tensor, factor=1.0
+):
+    """
+    Applies Adaptive Instance Normalization (AdaIN) to a latent tensor based on
+    statistics from a reference latent tensor.
+
+    Args:
+        latent (torch.Tensor): Input latents to normalize
+        reference_latent (torch.Tensor): The reference latents providing style statistics.
+        factor (float): Blending factor between original and transformed latent.
+                       Range: -10.0 to 10.0, Default: 1.0
+
+    Returns:
+        torch.Tensor: The transformed latent tensor
+    """
+    result = latents.clone()
+
+    for i in range(latents.size(0)):
+        for c in range(latents.size(1)):
+            r_sd, r_mean = torch.std_mean(
+                reference_latents[i, c], dim=None
+            )  # index by original dim order
+            i_sd, i_mean = torch.std_mean(result[i, c], dim=None)
+
+            result[i, c] = ((result[i, c] - i_mean) / i_sd) * r_sd + r_mean
+
+    result = torch.lerp(latents, result, factor)
+    return result
+
+
+class LTXMultiScalePipeline:
+    def _upsample_latents(
+        self, latest_upsampler: LatentUpsampler, latents: torch.Tensor
+    ):
+        assert latents.device == latest_upsampler.device
+
+        latents = un_normalize_latents(
+            latents, self.vae, vae_per_channel_normalize=True
+        )
+        upsampled_latents = latest_upsampler(latents)
+        upsampled_latents = normalize_latents(
+            upsampled_latents, self.vae, vae_per_channel_normalize=True
+        )
+        return upsampled_latents
+
+    def __init__(
+        self, video_pipeline: LTXVideoPipeline, latent_upsampler: LatentUpsampler
+    ):
+        self.video_pipeline = video_pipeline
+        self.vae = video_pipeline.vae
+        self.latent_upsampler = latent_upsampler
+
+    def __call__(
+        self,
+        downscale_factor: float,
+        first_pass: dict,
+        second_pass: dict,
+        *args: Any,
+        **kwargs: Any,
+    ) -> Any:
+        original_kwargs = kwargs.copy()
+        original_output_type = kwargs["output_type"]
+        original_width = kwargs["width"]
+        original_height = kwargs["height"]
+
+        x_width = int(kwargs["width"] * downscale_factor)
+        downscaled_width = x_width - (x_width % self.video_pipeline.vae_scale_factor)
+        x_height = int(kwargs["height"] * downscale_factor)
+        downscaled_height = x_height - (x_height % self.video_pipeline.vae_scale_factor)
+
+        kwargs["output_type"] = "latent"
+        kwargs["width"] = downscaled_width
+        kwargs["height"] = downscaled_height
+        kwargs.update(**first_pass)
+        result = self.video_pipeline(*args, **kwargs)
+        latents = result.images
+
+        upsampled_latents = self._upsample_latents(self.latent_upsampler, latents)
+        upsampled_latents = adain_filter_latent(
+            latents=upsampled_latents, reference_latents=latents
+        )
+
+        kwargs = original_kwargs
+
+        kwargs["latents"] = upsampled_latents
+        kwargs["output_type"] = original_output_type
+        kwargs["width"] = downscaled_width * 2
+        kwargs["height"] = downscaled_height * 2
+        kwargs.update(**second_pass)
+
+        result = self.video_pipeline(*args, **kwargs)
+        if original_output_type != "latent":
+            num_frames = result.images.shape[2]
+            videos = rearrange(result.images, "b c f h w -> (b f) c h w")
+
+            videos = F.interpolate(
+                videos,
+                size=(original_height, original_width),
+                mode="bilinear",
+                align_corners=False,
+            )
+            videos = rearrange(videos, "(b f) c h w -> b c f h w", f=num_frames)
+            result.images = videos
+
+        return result

ltx_video/schedulers/rf.py

@@ -0,0 +1,386 @@
+import math
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
+from typing import Callable, Optional, Tuple, Union
+import json
+import os
+from pathlib import Path
+
+import torch
+from diffusers.configuration_utils import ConfigMixin, register_to_config
+from diffusers.schedulers.scheduling_utils import SchedulerMixin
+from diffusers.utils import BaseOutput
+from torch import Tensor
+from safetensors import safe_open
+
+
+from ltx_video.utils.torch_utils import append_dims
+
+from ltx_video.utils.diffusers_config_mapping import (
+    diffusers_and_ours_config_mapping,
+    make_hashable_key,
+)
+
+
+def linear_quadratic_schedule(num_steps, threshold_noise=0.025, linear_steps=None):
+    if num_steps == 1:
+        return torch.tensor([1.0])
+    if linear_steps is None:
+        linear_steps = num_steps // 2
+    linear_sigma_schedule = [
+        i * threshold_noise / linear_steps for i in range(linear_steps)
+    ]
+    threshold_noise_step_diff = linear_steps - threshold_noise * num_steps
+    quadratic_steps = num_steps - linear_steps
+    quadratic_coef = threshold_noise_step_diff / (linear_steps * quadratic_steps**2)
+    linear_coef = threshold_noise / linear_steps - 2 * threshold_noise_step_diff / (
+        quadratic_steps**2
+    )
+    const = quadratic_coef * (linear_steps**2)
+    quadratic_sigma_schedule = [
+        quadratic_coef * (i**2) + linear_coef * i + const
+        for i in range(linear_steps, num_steps)
+    ]
+    sigma_schedule = linear_sigma_schedule + quadratic_sigma_schedule + [1.0]
+    sigma_schedule = [1.0 - x for x in sigma_schedule]
+    return torch.tensor(sigma_schedule[:-1])
+
+
+def simple_diffusion_resolution_dependent_timestep_shift(
+    samples_shape: torch.Size,
+    timesteps: Tensor,
+    n: int = 32 * 32,
+) -> Tensor:
+    if len(samples_shape) == 3:
+        _, m, _ = samples_shape
+    elif len(samples_shape) in [4, 5]:
+        m = math.prod(samples_shape[2:])
+    else:
+        raise ValueError(
+            "Samples must have shape (b, t, c), (b, c, h, w) or (b, c, f, h, w)"
+        )
+    snr = (timesteps / (1 - timesteps)) ** 2
+    shift_snr = torch.log(snr) + 2 * math.log(m / n)
+    shifted_timesteps = torch.sigmoid(0.5 * shift_snr)
+
+    return shifted_timesteps
+
+
+def time_shift(mu: float, sigma: float, t: Tensor):
+    return math.exp(mu) / (math.exp(mu) + (1 / t - 1) ** sigma)
+
+
+def get_normal_shift(
+    n_tokens: int,
+    min_tokens: int = 1024,
+    max_tokens: int = 4096,
+    min_shift: float = 0.95,
+    max_shift: float = 2.05,
+) -> Callable[[float], float]:
+    m = (max_shift - min_shift) / (max_tokens - min_tokens)
+    b = min_shift - m * min_tokens
+    return m * n_tokens + b
+
+
+def strech_shifts_to_terminal(shifts: Tensor, terminal=0.1):
+    """
+    Stretch a function (given as sampled shifts) so that its final value matches the given terminal value
+    using the provided formula.
+
+    Parameters:
+    - shifts (Tensor): The samples of the function to be stretched (PyTorch Tensor).
+    - terminal (float): The desired terminal value (value at the last sample).
+
+    Returns:
+    - Tensor: The stretched shifts such that the final value equals `terminal`.
+    """
+    if shifts.numel() == 0:
+        raise ValueError("The 'shifts' tensor must not be empty.")
+
+    # Ensure terminal value is valid
+    if terminal <= 0 or terminal >= 1:
+        raise ValueError("The terminal value must be between 0 and 1 (exclusive).")
+
+    # Transform the shifts using the given formula
+    one_minus_z = 1 - shifts
+    scale_factor = one_minus_z[-1] / (1 - terminal)
+    stretched_shifts = 1 - (one_minus_z / scale_factor)
+
+    return stretched_shifts
+
+
+def sd3_resolution_dependent_timestep_shift(
+    samples_shape: torch.Size,
+    timesteps: Tensor,
+    target_shift_terminal: Optional[float] = None,
+) -> Tensor:
+    """
+    Shifts the timestep schedule as a function of the generated resolution.
+
+    In the SD3 paper, the authors empirically how to shift the timesteps based on the resolution of the target images.
+    For more details: https://arxiv.org/pdf/2403.03206
+
+    In Flux they later propose a more dynamic resolution dependent timestep shift, see:
+    https://github.com/black-forest-labs/flux/blob/87f6fff727a377ea1c378af692afb41ae84cbe04/src/flux/sampling.py#L66
+
+
+    Args:
+        samples_shape (torch.Size): The samples batch shape (batch_size, channels, height, width) or
+            (batch_size, channels, frame, height, width).
+        timesteps (Tensor): A batch of timesteps with shape (batch_size,).
+        target_shift_terminal (float): The target terminal value for the shifted timesteps.
+
+    Returns:
+        Tensor: The shifted timesteps.
+    """
+    if len(samples_shape) == 3:
+        _, m, _ = samples_shape
+    elif len(samples_shape) in [4, 5]:
+        m = math.prod(samples_shape[2:])
+    else:
+        raise ValueError(
+            "Samples must have shape (b, t, c), (b, c, h, w) or (b, c, f, h, w)"
+        )
+
+    shift = get_normal_shift(m)
+    time_shifts = time_shift(shift, 1, timesteps)
+    if target_shift_terminal is not None:  # Stretch the shifts to the target terminal
+        time_shifts = strech_shifts_to_terminal(time_shifts, target_shift_terminal)
+    return time_shifts
+
+
+class TimestepShifter(ABC):
+    @abstractmethod
+    def shift_timesteps(self, samples_shape: torch.Size, timesteps: Tensor) -> Tensor:
+        pass
+
+
+@dataclass
+class RectifiedFlowSchedulerOutput(BaseOutput):
+    """
+    Output class for the scheduler's step function output.
+
+    Args:
+        prev_sample (`torch.FloatTensor` of shape `(batch_size, num_channels, height, width)` for images):
+            Computed sample (x_{t-1}) of previous timestep. `prev_sample` should be used as next model input in the
+            denoising loop.
+        pred_original_sample (`torch.FloatTensor` of shape `(batch_size, num_channels, height, width)` for images):
+            The predicted denoised sample (x_{0}) based on the model output from the current timestep.
+            `pred_original_sample` can be used to preview progress or for guidance.
+    """
+
+    prev_sample: torch.FloatTensor
+    pred_original_sample: Optional[torch.FloatTensor] = None
+
+
+class RectifiedFlowScheduler(SchedulerMixin, ConfigMixin, TimestepShifter):
+    order = 1
+
+    @register_to_config
+    def __init__(
+        self,
+        num_train_timesteps=1000,
+        shifting: Optional[str] = None,
+        base_resolution: int = 32**2,
+        target_shift_terminal: Optional[float] = None,
+        sampler: Optional[str] = "Uniform",
+        shift: Optional[float] = None,
+    ):
+        super().__init__()
+        self.init_noise_sigma = 1.0
+        self.num_inference_steps = None
+        self.sampler = sampler
+        self.shifting = shifting
+        self.base_resolution = base_resolution
+        self.target_shift_terminal = target_shift_terminal
+        self.timesteps = self.sigmas = self.get_initial_timesteps(
+            num_train_timesteps, shift=shift
+        )
+        self.shift = shift
+
+    def get_initial_timesteps(
+        self, num_timesteps: int, shift: Optional[float] = None
+    ) -> Tensor:
+        if self.sampler == "Uniform":
+            return torch.linspace(1, 1 / num_timesteps, num_timesteps)
+        elif self.sampler == "LinearQuadratic":
+            return linear_quadratic_schedule(num_timesteps)
+        elif self.sampler == "Constant":
+            assert (
+                shift is not None
+            ), "Shift must be provided for constant time shift sampler."
+            return time_shift(
+                shift, 1, torch.linspace(1, 1 / num_timesteps, num_timesteps)
+            )
+
+    def shift_timesteps(self, samples_shape: torch.Size, timesteps: Tensor) -> Tensor:
+        if self.shifting == "SD3":
+            return sd3_resolution_dependent_timestep_shift(
+                samples_shape, timesteps, self.target_shift_terminal
+            )
+        elif self.shifting == "SimpleDiffusion":
+            return simple_diffusion_resolution_dependent_timestep_shift(
+                samples_shape, timesteps, self.base_resolution
+            )
+        return timesteps
+
+    def set_timesteps(
+        self,
+        num_inference_steps: Optional[int] = None,
+        samples_shape: Optional[torch.Size] = None,
+        timesteps: Optional[Tensor] = None,
+        device: Union[str, torch.device] = None,
+    ):
+        """
+        Sets the discrete timesteps used for the diffusion chain. Supporting function to be run before inference.
+        If `timesteps` are provided, they will be used instead of the scheduled timesteps.
+
+        Args:
+            num_inference_steps (`int` *optional*): The number of diffusion steps used when generating samples.
+            samples_shape (`torch.Size` *optional*): The samples batch shape, used for shifting.
+            timesteps ('torch.Tensor' *optional*): Specific timesteps to use instead of scheduled timesteps.
+            device (`Union[str, torch.device]`, *optional*): The device to which the timesteps tensor will be moved.
+        """
+        if timesteps is not None and num_inference_steps is not None:
+            raise ValueError(
+                "You cannot provide both `timesteps` and `num_inference_steps`."
+            )
+        if timesteps is None:
+            num_inference_steps = min(
+                self.config.num_train_timesteps, num_inference_steps
+            )
+            timesteps = self.get_initial_timesteps(
+                num_inference_steps, shift=self.shift
+            ).to(device)
+            timesteps = self.shift_timesteps(samples_shape, timesteps)
+        else:
+            timesteps = torch.Tensor(timesteps).to(device)
+            num_inference_steps = len(timesteps)
+        self.timesteps = timesteps
+        self.num_inference_steps = num_inference_steps
+        self.sigmas = self.timesteps
+
+    @staticmethod
+    def from_pretrained(pretrained_model_path: Union[str, os.PathLike]):
+        pretrained_model_path = Path(pretrained_model_path)
+        if pretrained_model_path.is_file():
+            comfy_single_file_state_dict = {}
+            with safe_open(pretrained_model_path, framework="pt", device="cpu") as f:
+                metadata = f.metadata()
+                for k in f.keys():
+                    comfy_single_file_state_dict[k] = f.get_tensor(k)
+            configs = json.loads(metadata["config"])
+            config = configs["scheduler"]
+            del comfy_single_file_state_dict
+
+        elif pretrained_model_path.is_dir():
+            diffusers_noise_scheduler_config_path = (
+                pretrained_model_path / "scheduler" / "scheduler_config.json"
+            )
+
+            with open(diffusers_noise_scheduler_config_path, "r") as f:
+                scheduler_config = json.load(f)
+            hashable_config = make_hashable_key(scheduler_config)
+            if hashable_config in diffusers_and_ours_config_mapping:
+                config = diffusers_and_ours_config_mapping[hashable_config]
+        return RectifiedFlowScheduler.from_config(config)
+
+    def scale_model_input(
+        self, sample: torch.FloatTensor, timestep: Optional[int] = None
+    ) -> torch.FloatTensor:
+        # pylint: disable=unused-argument
+        """
+        Ensures interchangeability with schedulers that need to scale the denoising model input depending on the
+        current timestep.
+
+        Args:
+            sample (`torch.FloatTensor`): input sample
+            timestep (`int`, optional): current timestep
+
+        Returns:
+            `torch.FloatTensor`: scaled input sample
+        """
+        return sample
+
+    def step(
+        self,
+        model_output: torch.FloatTensor,
+        timestep: torch.FloatTensor,
+        sample: torch.FloatTensor,
+        return_dict: bool = True,
+        stochastic_sampling: Optional[bool] = False,
+        **kwargs,
+    ) -> Union[RectifiedFlowSchedulerOutput, Tuple]:
+        """
+        Predict the sample from the previous timestep by reversing the SDE. This function propagates the diffusion
+        process from the learned model outputs (most often the predicted noise).
+        z_{t_1} = z_t - \Delta_t * v
+        The method finds the next timestep that is lower than the input timestep(s) and denoises the latents
+        to that level. The input timestep(s) are not required to be one of the predefined timesteps.
+
+        Args:
+            model_output (`torch.FloatTensor`):
+                The direct output from learned diffusion model - the velocity,
+            timestep (`float`):
+                The current discrete timestep in the diffusion chain (global or per-token).
+            sample (`torch.FloatTensor`):
+                A current latent tokens to be de-noised.
+            return_dict (`bool`, *optional*, defaults to `True`):
+                Whether or not to return a [`~schedulers.scheduling_ddim.DDIMSchedulerOutput`] or `tuple`.
+            stochastic_sampling (`bool`, *optional*, defaults to `False`):
+                Whether to use stochastic sampling for the sampling process.
+
+        Returns:
+            [`~schedulers.scheduling_utils.RectifiedFlowSchedulerOutput`] or `tuple`:
+                If return_dict is `True`, [`~schedulers.rf_scheduler.RectifiedFlowSchedulerOutput`] is returned,
+                otherwise a tuple is returned where the first element is the sample tensor.
+        """
+        if self.num_inference_steps is None:
+            raise ValueError(
+                "Number of inference steps is 'None', you need to run 'set_timesteps' after creating the scheduler"
+            )
+        t_eps = 1e-6  # Small epsilon to avoid numerical issues in timestep values
+
+        timesteps_padded = torch.cat(
+            [self.timesteps, torch.zeros(1, device=self.timesteps.device)]
+        )
+
+        # Find the next lower timestep(s) and compute the dt from the current timestep(s)
+        if timestep.ndim == 0:
+            # Global timestep case
+            lower_mask = timesteps_padded < timestep - t_eps
+            lower_timestep = timesteps_padded[lower_mask][0]  # Closest lower timestep
+            dt = timestep - lower_timestep
+
+        else:
+            # Per-token case
+            assert timestep.ndim == 2
+            lower_mask = timesteps_padded[:, None, None] < timestep[None] - t_eps
+            lower_timestep = lower_mask * timesteps_padded[:, None, None]
+            lower_timestep, _ = lower_timestep.max(dim=0)
+            dt = (timestep - lower_timestep)[..., None]
+
+        # Compute previous sample
+        if stochastic_sampling:
+            x0 = sample - timestep[..., None] * model_output
+            next_timestep = timestep[..., None] - dt
+            prev_sample = self.add_noise(x0, torch.randn_like(sample), next_timestep)
+        else:
+            prev_sample = sample - dt * model_output
+
+        if not return_dict:
+            return (prev_sample,)
+
+        return RectifiedFlowSchedulerOutput(prev_sample=prev_sample)
+
+    def add_noise(
+        self,
+        original_samples: torch.FloatTensor,
+        noise: torch.FloatTensor,
+        timesteps: torch.FloatTensor,
+    ) -> torch.FloatTensor:
+        sigmas = timesteps
+        sigmas = append_dims(sigmas, original_samples.ndim)
+        alphas = 1 - sigmas
+        noisy_samples = alphas * original_samples + sigmas * noise
+        return noisy_samples

ltx_video/utils/diffusers_config_mapping.py

@@ -0,0 +1,174 @@
+def make_hashable_key(dict_key):
+    def convert_value(value):
+        if isinstance(value, list):
+            return tuple(value)
+        elif isinstance(value, dict):
+            return tuple(sorted((k, convert_value(v)) for k, v in value.items()))
+        else:
+            return value
+
+    return tuple(sorted((k, convert_value(v)) for k, v in dict_key.items()))
+
+
+DIFFUSERS_SCHEDULER_CONFIG = {
+    "_class_name": "FlowMatchEulerDiscreteScheduler",
+    "_diffusers_version": "0.32.0.dev0",
+    "base_image_seq_len": 1024,
+    "base_shift": 0.95,
+    "invert_sigmas": False,
+    "max_image_seq_len": 4096,
+    "max_shift": 2.05,
+    "num_train_timesteps": 1000,
+    "shift": 1.0,
+    "shift_terminal": 0.1,
+    "use_beta_sigmas": False,
+    "use_dynamic_shifting": True,
+    "use_exponential_sigmas": False,
+    "use_karras_sigmas": False,
+}
+DIFFUSERS_TRANSFORMER_CONFIG = {
+    "_class_name": "LTXVideoTransformer3DModel",
+    "_diffusers_version": "0.32.0.dev0",
+    "activation_fn": "gelu-approximate",
+    "attention_bias": True,
+    "attention_head_dim": 64,
+    "attention_out_bias": True,
+    "caption_channels": 4096,
+    "cross_attention_dim": 2048,
+    "in_channels": 128,
+    "norm_elementwise_affine": False,
+    "norm_eps": 1e-06,
+    "num_attention_heads": 32,
+    "num_layers": 28,
+    "out_channels": 128,
+    "patch_size": 1,
+    "patch_size_t": 1,
+    "qk_norm": "rms_norm_across_heads",
+}
+DIFFUSERS_VAE_CONFIG = {
+    "_class_name": "AutoencoderKLLTXVideo",
+    "_diffusers_version": "0.32.0.dev0",
+    "block_out_channels": [128, 256, 512, 512],
+    "decoder_causal": False,
+    "encoder_causal": True,
+    "in_channels": 3,
+    "latent_channels": 128,
+    "layers_per_block": [4, 3, 3, 3, 4],
+    "out_channels": 3,
+    "patch_size": 4,
+    "patch_size_t": 1,
+    "resnet_norm_eps": 1e-06,
+    "scaling_factor": 1.0,
+    "spatio_temporal_scaling": [True, True, True, False],
+}
+
+OURS_SCHEDULER_CONFIG = {
+    "_class_name": "RectifiedFlowScheduler",
+    "_diffusers_version": "0.25.1",
+    "num_train_timesteps": 1000,
+    "shifting": "SD3",
+    "base_resolution": None,
+    "target_shift_terminal": 0.1,
+}
+
+OURS_TRANSFORMER_CONFIG = {
+    "_class_name": "Transformer3DModel",
+    "_diffusers_version": "0.25.1",
+    "_name_or_path": "PixArt-alpha/PixArt-XL-2-256x256",
+    "activation_fn": "gelu-approximate",
+    "attention_bias": True,
+    "attention_head_dim": 64,
+    "attention_type": "default",
+    "caption_channels": 4096,
+    "cross_attention_dim": 2048,
+    "double_self_attention": False,
+    "dropout": 0.0,
+    "in_channels": 128,
+    "norm_elementwise_affine": False,
+    "norm_eps": 1e-06,
+    "norm_num_groups": 32,
+    "num_attention_heads": 32,
+    "num_embeds_ada_norm": 1000,
+    "num_layers": 28,
+    "num_vector_embeds": None,
+    "only_cross_attention": False,
+    "out_channels": 128,
+    "project_to_2d_pos": True,
+    "upcast_attention": False,
+    "use_linear_projection": False,
+    "qk_norm": "rms_norm",
+    "standardization_norm": "rms_norm",
+    "positional_embedding_type": "rope",
+    "positional_embedding_theta": 10000.0,
+    "positional_embedding_max_pos": [20, 2048, 2048],
+    "timestep_scale_multiplier": 1000,
+}
+OURS_VAE_CONFIG = {
+    "_class_name": "CausalVideoAutoencoder",
+    "dims": 3,
+    "in_channels": 3,
+    "out_channels": 3,
+    "latent_channels": 128,
+    "blocks": [
+        ["res_x", 4],
+        ["compress_all", 1],
+        ["res_x_y", 1],
+        ["res_x", 3],
+        ["compress_all", 1],
+        ["res_x_y", 1],
+        ["res_x", 3],
+        ["compress_all", 1],
+        ["res_x", 3],
+        ["res_x", 4],
+    ],
+    "scaling_factor": 1.0,
+    "norm_layer": "pixel_norm",
+    "patch_size": 4,
+    "latent_log_var": "uniform",
+    "use_quant_conv": False,
+    "causal_decoder": False,
+}
+
+
+diffusers_and_ours_config_mapping = {
+    make_hashable_key(DIFFUSERS_SCHEDULER_CONFIG): OURS_SCHEDULER_CONFIG,
+    make_hashable_key(DIFFUSERS_TRANSFORMER_CONFIG): OURS_TRANSFORMER_CONFIG,
+    make_hashable_key(DIFFUSERS_VAE_CONFIG): OURS_VAE_CONFIG,
+}
+
+
+TRANSFORMER_KEYS_RENAME_DICT = {
+    "proj_in": "patchify_proj",
+    "time_embed": "adaln_single",
+    "norm_q": "q_norm",
+    "norm_k": "k_norm",
+}
+
+
+VAE_KEYS_RENAME_DICT = {
+    "decoder.up_blocks.3.conv_in": "decoder.up_blocks.7",
+    "decoder.up_blocks.3.upsamplers.0": "decoder.up_blocks.8",
+    "decoder.up_blocks.3": "decoder.up_blocks.9",
+    "decoder.up_blocks.2.upsamplers.0": "decoder.up_blocks.5",
+    "decoder.up_blocks.2.conv_in": "decoder.up_blocks.4",
+    "decoder.up_blocks.2": "decoder.up_blocks.6",
+    "decoder.up_blocks.1.upsamplers.0": "decoder.up_blocks.2",
+    "decoder.up_blocks.1": "decoder.up_blocks.3",
+    "decoder.up_blocks.0": "decoder.up_blocks.1",
+    "decoder.mid_block": "decoder.up_blocks.0",
+    "encoder.down_blocks.3": "encoder.down_blocks.8",
+    "encoder.down_blocks.2.downsamplers.0": "encoder.down_blocks.7",
+    "encoder.down_blocks.2": "encoder.down_blocks.6",
+    "encoder.down_blocks.1.downsamplers.0": "encoder.down_blocks.4",
+    "encoder.down_blocks.1.conv_out": "encoder.down_blocks.5",
+    "encoder.down_blocks.1": "encoder.down_blocks.3",
+    "encoder.down_blocks.0.conv_out": "encoder.down_blocks.2",
+    "encoder.down_blocks.0.downsamplers.0": "encoder.down_blocks.1",
+    "encoder.down_blocks.0": "encoder.down_blocks.0",
+    "encoder.mid_block": "encoder.down_blocks.9",
+    "conv_shortcut.conv": "conv_shortcut",
+    "resnets": "res_blocks",
+    "norm3": "norm3.norm",
+    "latents_mean": "per_channel_statistics.mean-of-means",
+    "latents_std": "per_channel_statistics.std-of-means",
+}

ltx_video/utils/prompt_enhance_utils.py

@@ -0,0 +1,226 @@
+import logging
+from typing import Union, List, Optional
+
+import torch
+from PIL import Image
+
+logger = logging.getLogger(__name__)  # pylint: disable=invalid-name
+
+T2V_CINEMATIC_PROMPT = """You are an expert cinematic director with many award winning movies, When writing prompts based on the user input, focus on detailed, chronological descriptions of actions and scenes.
+Include specific movements, appearances, camera angles, and environmental details - all in a single flowing paragraph.
+Start directly with the action, and keep descriptions literal and precise.
+Think like a cinematographer describing a shot list.
+Do not change the user input intent, just enhance it.
+Keep within 150 words.
+For best results, build your prompts using this structure:
+Start with main action in a single sentence
+Add specific details about movements and gestures
+Describe character/object appearances precisely
+Include background and environment details
+Specify camera angles and movements
+Describe lighting and colors
+Note any changes or sudden events
+Do not exceed the 150 word limit!
+Output the enhanced prompt only.
+"""
+
+I2V_CINEMATIC_PROMPT = """You are an expert cinematic director with many award winning movies, When writing prompts based on the user input, focus on detailed, chronological descriptions of actions and scenes.
+Include specific movements, appearances, camera angles, and environmental details - all in a single flowing paragraph.
+Start directly with the action, and keep descriptions literal and precise.
+Think like a cinematographer describing a shot list.
+Keep within 150 words.
+For best results, build your prompts using this structure:
+Describe the image first and then add the user input. Image description should be in first priority! Align to the image caption if it contradicts the user text input.
+Start with main action in a single sentence
+Add specific details about movements and gestures
+Describe character/object appearances precisely
+Include background and environment details
+Specify camera angles and movements
+Describe lighting and colors
+Note any changes or sudden events
+Align to the image caption if it contradicts the user text input.
+Do not exceed the 150 word limit!
+Output the enhanced prompt only.
+"""
+
+
+def tensor_to_pil(tensor):
+    # Ensure tensor is in range [-1, 1]
+    assert tensor.min() >= -1 and tensor.max() <= 1
+
+    # Convert from [-1, 1] to [0, 1]
+    tensor = (tensor + 1) / 2
+
+    # Rearrange from [C, H, W] to [H, W, C]
+    tensor = tensor.permute(1, 2, 0)
+
+    # Convert to numpy array and then to uint8 range [0, 255]
+    numpy_image = (tensor.cpu().numpy() * 255).astype("uint8")
+
+    # Convert to PIL Image
+    return Image.fromarray(numpy_image)
+
+
+def generate_cinematic_prompt(
+    image_caption_model,
+    image_caption_processor,
+    prompt_enhancer_model,
+    prompt_enhancer_tokenizer,
+    prompt: Union[str, List[str]],
+    conditioning_items: Optional[List] = None,
+    max_new_tokens: int = 256,
+) -> List[str]:
+    prompts = [prompt] if isinstance(prompt, str) else prompt
+
+    if conditioning_items is None:
+        prompts = _generate_t2v_prompt(
+            prompt_enhancer_model,
+            prompt_enhancer_tokenizer,
+            prompts,
+            max_new_tokens,
+            T2V_CINEMATIC_PROMPT,
+        )
+    else:
+        if len(conditioning_items) > 1 or conditioning_items[0].media_frame_number != 0:
+            logger.warning(
+                "prompt enhancement does only support unconditional or first frame of conditioning items, returning original prompts"
+            )
+            return prompts
+
+        first_frame_conditioning_item = conditioning_items[0]
+        first_frames = _get_first_frames_from_conditioning_item(
+            first_frame_conditioning_item
+        )
+
+        assert len(first_frames) == len(
+            prompts
+        ), "Number of conditioning frames must match number of prompts"
+
+        prompts = _generate_i2v_prompt(
+            image_caption_model,
+            image_caption_processor,
+            prompt_enhancer_model,
+            prompt_enhancer_tokenizer,
+            prompts,
+            first_frames,
+            max_new_tokens,
+            I2V_CINEMATIC_PROMPT,
+        )
+
+    return prompts
+
+
+def _get_first_frames_from_conditioning_item(conditioning_item) -> List[Image.Image]:
+    frames_tensor = conditioning_item.media_item
+    return [
+        tensor_to_pil(frames_tensor[i, :, 0, :, :])
+        for i in range(frames_tensor.shape[0])
+    ]
+
+
+def _generate_t2v_prompt(
+    prompt_enhancer_model,
+    prompt_enhancer_tokenizer,
+    prompts: List[str],
+    max_new_tokens: int,
+    system_prompt: str,
+) -> List[str]:
+    messages = [
+        [
+            {"role": "system", "content": system_prompt},
+            {"role": "user", "content": f"user_prompt: {p}"},
+        ]
+        for p in prompts
+    ]
+
+    texts = [
+        prompt_enhancer_tokenizer.apply_chat_template(
+            m, tokenize=False, add_generation_prompt=True
+        )
+        for m in messages
+    ]
+    model_inputs = prompt_enhancer_tokenizer(texts, return_tensors="pt").to(
+        prompt_enhancer_model.device
+    )
+
+    return _generate_and_decode_prompts(
+        prompt_enhancer_model, prompt_enhancer_tokenizer, model_inputs, max_new_tokens
+    )
+
+
+def _generate_i2v_prompt(
+    image_caption_model,
+    image_caption_processor,
+    prompt_enhancer_model,
+    prompt_enhancer_tokenizer,
+    prompts: List[str],
+    first_frames: List[Image.Image],
+    max_new_tokens: int,
+    system_prompt: str,
+) -> List[str]:
+    image_captions = _generate_image_captions(
+        image_caption_model, image_caption_processor, first_frames
+    )
+
+    messages = [
+        [
+            {"role": "system", "content": system_prompt},
+            {"role": "user", "content": f"user_prompt: {p}\nimage_caption: {c}"},
+        ]
+        for p, c in zip(prompts, image_captions)
+    ]
+
+    texts = [
+        prompt_enhancer_tokenizer.apply_chat_template(
+            m, tokenize=False, add_generation_prompt=True
+        )
+        for m in messages
+    ]
+    model_inputs = prompt_enhancer_tokenizer(texts, return_tensors="pt").to(
+        prompt_enhancer_model.device
+    )
+
+    return _generate_and_decode_prompts(
+        prompt_enhancer_model, prompt_enhancer_tokenizer, model_inputs, max_new_tokens
+    )
+
+
+def _generate_image_captions(
+    image_caption_model,
+    image_caption_processor,
+    images: List[Image.Image],
+    system_prompt: str = "<DETAILED_CAPTION>",
+) -> List[str]:
+    image_caption_prompts = [system_prompt] * len(images)
+    inputs = image_caption_processor(
+        image_caption_prompts, images, return_tensors="pt"
+    ).to(image_caption_model.device)
+
+    with torch.inference_mode():
+        generated_ids = image_caption_model.generate(
+            input_ids=inputs["input_ids"],
+            pixel_values=inputs["pixel_values"],
+            max_new_tokens=1024,
+            do_sample=False,
+            num_beams=3,
+        )
+
+    return image_caption_processor.batch_decode(generated_ids, skip_special_tokens=True)
+
+
+def _generate_and_decode_prompts(
+    prompt_enhancer_model, prompt_enhancer_tokenizer, model_inputs, max_new_tokens: int
+) -> List[str]:
+    with torch.inference_mode():
+        outputs = prompt_enhancer_model.generate(
+            **model_inputs, max_new_tokens=max_new_tokens
+        )
+        generated_ids = [
+            output_ids[len(input_ids) :]
+            for input_ids, output_ids in zip(model_inputs.input_ids, outputs)
+        ]
+        decoded_prompts = prompt_enhancer_tokenizer.batch_decode(
+            generated_ids, skip_special_tokens=True
+        )
+
+    return decoded_prompts

ltx_video/utils/skip_layer_strategy.py

@@ -0,0 +1,8 @@
+from enum import Enum, auto
+
+
+class SkipLayerStrategy(Enum):
+    AttentionSkip = auto()
+    AttentionValues = auto()
+    Residual = auto()
+    TransformerBlock = auto()

ltx_video/utils/torch_utils.py

@@ -0,0 +1,25 @@
+import torch
+from torch import nn
+
+
+def append_dims(x: torch.Tensor, target_dims: int) -> torch.Tensor:
+    """Appends dimensions to the end of a tensor until it has target_dims dimensions."""
+    dims_to_append = target_dims - x.ndim
+    if dims_to_append < 0:
+        raise ValueError(
+            f"input has {x.ndim} dims but target_dims is {target_dims}, which is less"
+        )
+    elif dims_to_append == 0:
+        return x
+    return x[(...,) + (None,) * dims_to_append]
+
+
+class Identity(nn.Module):
+    """A placeholder identity operator that is argument-insensitive."""
+
+    def __init__(self, *args, **kwargs) -> None:  # pylint: disable=unused-argument
+        super().__init__()
+
+    # pylint: disable=unused-argument
+    def forward(self, x: torch.Tensor, *args, **kwargs) -> torch.Tensor:
+        return x