whisper.py

from pydub import AudioSegment
import os
import torchaudio
import torch
import re
from transformers import pipeline, WhisperForConditionalGeneration, WhisperProcessor, GenerationConfig
from pyannote.audio import Pipeline as DiarizationPipeline
import whisperx
import whisper_timestamped as whisper_ts
import spaces
from typing import Dict

device = 0 if torch.cuda.is_available() else "cpu"
torch_dtype = torch.float32

MODEL_PATH_1 = "./whisper-large-v3-tiny-caesar"
MODEL_PATH_2 = "langtech-veu/whisper-timestamped-cs"
DEVICE = "cuda" if torch.cuda.is_available() else "cpu"

def clean_text(input_text):
    remove_chars = ['.', ',', ';', ':', '¿', '?', '«', '»', '-', '¡', '!', '@',
                    '*', '{', '}', '[', ']', '=', '/', '\\', '&', '#', '…']
    output_text = ''.join(char if char not in remove_chars else ' ' for char in input_text)
    return ' '.join(output_text.split()).lower()


def split_stereo_channels(audio_path):

    audio = AudioSegment.from_wav(audio_path)
    
    channels = audio.split_to_mono()
    if len(channels) != 2:
        raise ValueError(f"Audio {audio_path} does not have 2 channels.")

    channels[0].export(f"temp_mono_speaker1.wav", format="wav")  # Right
    channels[1].export(f"temp_mono_speaker2.wav", format="wav")  # Left


def convert_to_mono(input_path):
    audio = AudioSegment.from_file(input_path)
    base, ext = os.path.splitext(input_path)
    output_path = f"{base}_merged.wav"
    mono = audio.set_channels(1)
    mono.export(output_path, format="wav")
    return output_path

def save_temp_audio(waveform, sample_rate, path):
    waveform = waveform.unsqueeze(0) if waveform.dim() == 1 else waveform
    torchaudio.save(path, waveform, sample_rate)

def format_audio(audio_path):
    input_audio, sample_rate = torchaudio.load(audio_path)
    if input_audio.shape[0] == 2:
        input_audio = torch.mean(input_audio, dim=0, keepdim=True)
    resampler = torchaudio.transforms.Resample(orig_freq=sample_rate, new_freq=16000)
    input_audio = resampler(input_audio)
    return input_audio.squeeze(), 16000

def assign_timestamps(asr_segments, audio_path):
    waveform, sr = format_audio(audio_path)
    total_duration = waveform.shape[-1] / sr

    total_words = sum(len(seg["text"].split()) for seg in asr_segments)
    if total_words == 0:
        raise ValueError("Total number of words in ASR segments is zero. Cannot assign timestamps.")

    avg_word_duration = total_duration / total_words

    current_time = 0.0
    for segment in asr_segments:
        word_count = len(segment["text"].split())
        segment_duration = word_count * avg_word_duration
        segment["start"] = round(current_time, 3)
        segment["end"] = round(current_time + segment_duration, 3)
        current_time += segment_duration

    return asr_segments

def hf_chunks_to_whisperx_segments(chunks):
    return [
        {
            "text": chunk["text"],
            "start": chunk["timestamp"][0],
            "end": chunk["timestamp"][1],
        }
        for chunk in chunks
        if chunk["timestamp"] and isinstance(chunk["timestamp"], (list, tuple))
    ]

def align_words_to_segments(words, segments, window=5.0):
    aligned = []
    seg_idx = 0
    for word in words:
        while seg_idx < len(segments) and segments[seg_idx]["end"] < word["start"] - window:
            seg_idx += 1
        for j in range(seg_idx, len(segments)):
            seg = segments[j]
            if seg["start"] > word["end"] + window:
                break
            if seg["start"] <= word["start"] < seg["end"]:
                aligned.append((word, seg))
                break
    return aligned
    
def post_process_transcription(transcription, max_repeats=2): 
    tokens = re.findall(r'\b\w+\'?\w*\b[.,!?]?', transcription)

    cleaned_tokens = []
    repetition_count = 0
    previous_token = None

    for token in tokens:
        reduced_token = re.sub(r"(\w{1,3})(\1{2,})", "", token)

        if reduced_token == previous_token:
            repetition_count += 1
            if repetition_count <= max_repeats:
                cleaned_tokens.append(reduced_token)
        else:
            repetition_count = 1
            cleaned_tokens.append(reduced_token)

        previous_token = reduced_token

    cleaned_transcription = " ".join(cleaned_tokens)
    cleaned_transcription = re.sub(r'\s+', ' ', cleaned_transcription).strip()

    return cleaned_transcription

def post_merge_consecutive_segments(input_file, output_file): #check
    with open(input_file, "r") as f:
        transcription_text = f.read()

    segments = re.split(r'(\[SPEAKER_\d{2}\])', transcription_text)
    merged_transcription = ''
    current_speaker = None
    current_segment = []

    for i in range(1, len(segments) - 1, 2):
        speaker_tag = segments[i]
        text = segments[i + 1].strip()

        speaker = re.search(r'\d{2}', speaker_tag).group()

        if speaker == current_speaker:
            current_segment.append(text)
        else:
            if current_speaker is not None:
                merged_transcription += f'[SPEAKER_{current_speaker}] {" ".join(current_segment)}\n'
            current_speaker = speaker
            current_segment = [text]

    if current_speaker is not None:
        merged_transcription += f'[SPEAKER_{current_speaker}] {" ".join(current_segment)}\n'

    with open(output_file, "w") as f:
        f.write(merged_transcription.strip())

def cleanup_temp_files(*file_paths):
    for path in file_paths:
        if path and os.path.exists(path):
            os.remove(path)



def load_whisper_model(model_path: str):
    device = "cuda" if torch.cuda.is_available() else "cpu"
    model = whisper_ts.load_model(model_path, device=device)
    return model

def transcribe_audio(model, audio_path: str) -> Dict:
    try:
        result = whisper_ts.transcribe(
            model,
            audio_path,
            beam_size=5,
            best_of=5,
            temperature=(0.0, 0.2, 0.4, 0.6, 0.8, 1.0),
            vad=False,  
            detect_disfluencies=True,
        )
        
        words = []
        for segment in result.get('segments', []):
            for word in segment.get('words', []):
                word_text = word.get('word', '').strip()
                if word_text.startswith(' '):
                    word_text = word_text[1:]
                
                words.append({
                    'word': word_text,
                    'start': word.get('start', 0),
                    'end': word.get('end', 0),
                    'confidence': word.get('confidence', 0)
                })
        
        return {
            'audio_path': audio_path,
            'text': result['text'].strip(),
            'segments': result.get('segments', []),
            'words': words,
            'duration': result.get('duration', 0),
            'success': True
        }
        
    except Exception as e:
        return {
            'audio_path': audio_path,
            'error': str(e),
            'success': False
        }
        


diarization_pipeline = DiarizationPipeline.from_pretrained("pyannote/diarization_config.yaml")
align_model, metadata = whisperx.load_align_model(language_code="en", device=DEVICE)

asr_pipe = pipeline(
    task="automatic-speech-recognition",
    model=MODEL_PATH_1,
    chunk_length_s=30,
    device=DEVICE,
    return_timestamps=True)

def diarization(audio_path):
    diarization_result = diarization_pipeline(audio_path) 
    diarized_segments = list(diarization_result.itertracks(yield_label=True))
    return diarized_segments

def asr(audio_path):
    asr_result = asr_pipe(audio_path, return_timestamps=True)
    asr_segments = hf_chunks_to_whisperx_segments(asr_result['chunks'])
    asr_segments = assign_timestamps(asr_segments, audio_path)
    return asr_segments

def align_asr_to_diarization(asr_segments, diarized_segments, audio_path):
    waveform, sample_rate = format_audio(audio_path)
    
    word_segments = whisperx.align(asr_segments, align_model, metadata, waveform, DEVICE)
    words = word_segments['word_segments']

    diarized = [{"start": segment.start,"end": segment.end,"speaker": speaker} for segment, _, speaker in diarized_segments]

    aligned_pairs = align_words_to_segments(words, diarized)

    output = []
    segment_map = {}
    for word, segment in aligned_pairs:
        key = (segment["start"], segment["end"], segment["speaker"])
        if key not in segment_map:
            segment_map[key] = []
        segment_map[key].append(word["word"])

    for (start, end, speaker), words in sorted(segment_map.items()):
        output.append(f"[{speaker}] {' '.join(words)}")

    return output

def generate(audio_path, use_v2):

    if use_v2:
        model = load_whisper_model(MODEL_PATH_2)
        split_stereo_channels(audio_path)

        audio_id = os.path.splitext(os.path.basename(audio_path))[0]

        left_channel_path = "temp_mono_speaker2.wav"
        right_channel_path = "temp_mono_speaker1.wav"
        
        left_waveform, left_sr = format_audio(left_channel_path)
        right_waveform, right_sr = format_audio(right_channel_path)
        left_result = transcribe_audio(model, left_waveform)
        right_result = transcribe_audio(model, right_waveform)

        def get_segments(result, speaker_label):
            segments = result.get("segments", [])
            if not segments:
                return []
            return [
                (seg.get("start", 0.0), seg.get("end", 0.0), speaker_label, post_process_transcription(seg.get("text", "").strip()))
                for seg in segments if seg.get("text")
            ]

        left_segs = get_segments(left_result, "Speaker 1")
        right_segs = get_segments(right_result, "Speaker 2")

        merged_transcript = sorted(
            left_segs + right_segs,
            key=lambda x: float(x[0]) if x[0] is not None else float("inf")
        )     
        
        output = ""
        for start, end, speaker, text in merged_transcript:
            output += f"[{speaker}]: {text}\n"        
       
        clean_output = output.strip()
        
    else: 
        mono_audio_path = convert_to_mono(audio_path)
        waveform, sr = format_audio(mono_audio_path)
        tmp_full_path = "tmp_full.wav"
        save_temp_audio(waveform, sr, tmp_full_path)
        diarized_segments = diarization(tmp_full_path)
        asr_segments = asr(tmp_full_path)
        for segment in asr_segments:
            segment["text"] = post_process_transcription(segment["text"])
        aligned_text = align_asr_to_diarization(asr_segments, diarized_segments, tmp_full_path)
        
        clean_output = ""
        for line in aligned_text:
            clean_output += f"{line}\n"
        cleanup_temp_files(mono_audio_path,tmp_full_path)

    cleanup_temp_files(
        "temp_mono_speaker1.wav",
        "temp_mono_speaker2.wav"
    )

    return clean_output