utils.py

from pydub import AudioSegment, silence
import tempfile
import hashlib
import matplotlib.pylab as plt
import librosa
from transformers import pipeline
import re
import torch
import numpy as np
import os
from scipy.io import wavfile
from scipy.signal import resample_poly

_ref_audio_cache = {}
asr_pipe = None

def resample_to_24khz(input_path: str, output_path: str):
    """
    Resample WAV audio file to 24,000 Hz using scipy.

    Parameters:
    - input_path (str): Path to the input WAV file.
    - output_path (str): Path to save the output WAV file.
    """
    # Load WAV file
    orig_sr, audio = wavfile.read(input_path)

    # Convert to mono if stereo
    if len(audio.shape) == 2:
        audio = audio.mean(axis=1)

    # Convert to float32 for processing
    if audio.dtype != np.float32:
        audio = audio.astype(np.float32) / np.iinfo(audio.dtype).max

    # Resample
    target_sr = 24000
    resampled = resample_poly(audio, target_sr, orig_sr)

    # Convert back to int16 for saving
    resampled_int16 = (resampled * 32767).astype(np.int16)

    # Save output
    wavfile.write(output_path, target_sr, resampled_int16)

def chunk_text(text, max_chars=135):

    # print(text)

    # Bước 1: Tách câu theo dấu ". "
    sentences = [s.strip() for s in text.split('. ') if s.strip()]
    
    # Ghép câu ngắn hơn 4 từ với câu liền kề
    i = 0
    while i < len(sentences):
        if len(sentences[i].split()) < 4:
            if i == 0 and i + 1 < len(sentences):
                # Ghép với câu sau
                sentences[i + 1] = sentences[i] + ', ' + sentences[i + 1]
                del sentences[i]
            else:
                if i - 1 >= 0:
                    # Ghép với câu trước
                    sentences[i - 1] = sentences[i - 1] + ', ' + sentences[i]
                    del sentences[i]
                    i -= 1
        else:
            i += 1

    # print(sentences)

    # Bước 2: Tách phần quá dài trong câu theo dấu ", "
    final_sentences = []
    for sentence in sentences:
        parts = [p.strip() for p in sentence.split(', ')]
        buffer = []
        for part in parts:
            buffer.append(part)
            total_words = sum(len(p.split()) for p in buffer)
            if total_words > 20:
                # Tách câu ra
                long_part = ', '.join(buffer)
                final_sentences.append(long_part)
                buffer = []
        if buffer:
            final_sentences.append(', '.join(buffer))

    # print(final_sentences)

    if len(final_sentences[-1].split()) < 4 and len(final_sentences) >= 2:
        final_sentences[-2] = final_sentences[-2] + ", " + final_sentences[-1]
        final_sentences = final_sentences[0:-1]
    
    # print(final_sentences)

    return final_sentences

def initialize_asr_pipeline(device="cuda", dtype=None):
    if dtype is None:
        dtype = (
            torch.float16
            if "cuda" in device
            and torch.cuda.get_device_properties(device).major >= 6
            and not torch.cuda.get_device_name().endswith("[ZLUDA]")
            else torch.float32
        )
    global asr_pipe
    asr_pipe = pipeline(
        "automatic-speech-recognition",
        model="vinai/PhoWhisper-medium",
        torch_dtype=dtype,
        device=device,
    )

# transcribe
def transcribe(ref_audio, language=None):
    global asr_pipe
    if asr_pipe is None:
        initialize_asr_pipeline(device="cuda")
    return asr_pipe(
        ref_audio,
        chunk_length_s=30,
        batch_size=128,
        generate_kwargs={"task": "transcribe", "language": language} if language else {"task": "transcribe"},
        return_timestamps=False,
    )["text"].strip()

def caculate_spec(audio):
    # Compute spectrogram (Short-Time Fourier Transform)
    stft = librosa.stft(audio, n_fft=512, hop_length=256, win_length=512)
    spectrogram = np.abs(stft)
    # Convert to dB
    spectrogram_db = librosa.amplitude_to_db(spectrogram, ref=np.max)
    return spectrogram_db

def save_spectrogram(audio, path):
    spectrogram = caculate_spec(audio)
    plt.figure(figsize=(12, 4))
    plt.imshow(spectrogram, origin="lower", aspect="auto")
    plt.colorbar()
    plt.savefig(path)
    plt.close()

def remove_silence_edges(audio, silence_threshold=-42):
    # Remove silence from the start
    non_silent_start_idx = silence.detect_leading_silence(audio, silence_threshold=silence_threshold)
    audio = audio[non_silent_start_idx:]

    # Remove silence from the end
    non_silent_end_duration = audio.duration_seconds
    for ms in reversed(audio):
        if ms.dBFS > silence_threshold:
            break
        non_silent_end_duration -= 0.001
    trimmed_audio = audio[: int(non_silent_end_duration * 1000)]

    return trimmed_audio

def preprocess_ref_audio_text(ref_audio_orig, ref_text, clip_short=True, show_info=print, device="cuda"):

    show_info("Converting audio...")

    resample_to_24khz(ref_audio_orig, ref_audio_orig_converted)

    ref_audio_orig = ref_audio_orig_converted

    with tempfile.NamedTemporaryFile(delete=False, suffix=".wav") as f:

        aseg = AudioSegment.from_file(ref_audio_orig)

        if clip_short:
            # 1. try to find long silence for clipping
            non_silent_segs = silence.split_on_silence(
                aseg, min_silence_len=1000, silence_thresh=-50, keep_silence=1000, seek_step=10
            )
            non_silent_wave = AudioSegment.silent(duration=0)
            for non_silent_seg in non_silent_segs:
                if len(non_silent_wave) > 6000 and len(non_silent_wave + non_silent_seg) > 15000:
                    show_info("Audio is over 15s, clipping short. (1)")
                    break
                non_silent_wave += non_silent_seg

            # 2. try to find short silence for clipping if 1. failed
            if len(non_silent_wave) > 15000:
                non_silent_segs = silence.split_on_silence(
                    aseg, min_silence_len=100, silence_thresh=-40, keep_silence=1000, seek_step=10
                )
                non_silent_wave = AudioSegment.silent(duration=0)
                for non_silent_seg in non_silent_segs:
                    if len(non_silent_wave) > 6000 and len(non_silent_wave + non_silent_seg) > 15000:
                        show_info("Audio is over 15s, clipping short. (2)")
                        break
                    non_silent_wave += non_silent_seg

            aseg = non_silent_wave

            # 3. if no proper silence found for clipping
            if len(aseg) > 15000:
                aseg = aseg[:15000]
                show_info("Audio is over 15s, clipping short. (3)")

        aseg = remove_silence_edges(aseg) + AudioSegment.silent(duration=50)
        aseg.export(f.name, format="wav")
        ref_audio = f.name

    # Compute a hash of the reference audio file
    with open(ref_audio, "rb") as audio_file:
        audio_data = audio_file.read()
        audio_hash = hashlib.md5(audio_data).hexdigest()

    if not ref_text.strip():
        global _ref_audio_cache
        if audio_hash in _ref_audio_cache:
            # Use cached asr transcription
            show_info("Using cached reference text...")
            ref_text = _ref_audio_cache[audio_hash]
        else:
            show_info("No reference text provided, transcribing reference audio...")
            ref_text = transcribe(ref_audio)
            # Cache the transcribed text (not caching custom ref_text, enabling users to do manual tweak)
            _ref_audio_cache[audio_hash] = ref_text
    else:
        show_info("Using custom reference text...")

    # Ensure ref_text ends with a proper sentence-ending punctuation
    if not ref_text.endswith(". ") and not ref_text.endswith("。"):
        if ref_text.endswith("."):
            ref_text += " "
        else:
            ref_text += ". "

    print("\nref_text  ", ref_text)

    return ref_audio, ref_text