Files
nlp-master/transcribe.py
Marius Mutu 763999f3a9 feat: anti-hallucination params + retranscribe script for fixing broken transcripts
- transcribe.py: add --max-context 0, --entropy-thold 2.4, --max-len 60,
  --suppress-nst, --no-fallback to whisper.cpp to prevent hallucination loops
- transcribe.py: remove interactive quality gate (runs unattended now)
- run.bat: remove pause prompts for unattended operation
- retranscribe_tail.py: new script that detects hallucination bursts in SRT
  files, extracts and re-transcribes only the affected audio segments, then
  splices the result back together. Drops segments that re-hallucinate
  (silence/music). Backs up originals to transcripts/backup/.
- fix_hallucinations.bat: Windows wrapper for retranscribe_tail.py

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 21:17:14 +02:00

297 lines
9.5 KiB
Python

"""
Batch transcription using whisper.cpp.
Reads manifest.json, transcribes each audio file in module order,
outputs .txt and .srt files, updates manifest status.
Resumable: skips files with existing transcripts.
Converts MP3 -> WAV (16kHz mono) via ffmpeg before transcription.
"""
import json
import logging
import os
import shutil
import subprocess
import sys
from pathlib import Path
MANIFEST_PATH = Path("manifest.json")
TRANSCRIPTS_DIR = Path("transcripts")
WAV_CACHE_DIR = Path("audio_wav")
# whisper.cpp defaults — override with env vars or CLI args
WHISPER_BIN = os.getenv("WHISPER_BIN", r"whisper-cli.exe")
WHISPER_MODEL = os.getenv("WHISPER_MODEL", r"models\ggml-medium-q5_0.bin")
logging.basicConfig(
level=logging.INFO,
format="%(asctime)s [%(levelname)s] %(message)s",
handlers=[
logging.StreamHandler(),
logging.FileHandler("transcribe_errors.log"),
],
)
log = logging.getLogger(__name__)
def find_ffmpeg() -> str:
"""Find ffmpeg executable."""
if shutil.which("ffmpeg"):
return "ffmpeg"
# Check local directories
for p in [Path("ffmpeg.exe"), Path("ffmpeg-bin/ffmpeg.exe")]:
if p.exists():
return str(p.resolve())
# Try imageio-ffmpeg (pip fallback)
try:
import imageio_ffmpeg
return imageio_ffmpeg.get_ffmpeg_exe()
except ImportError:
pass
return ""
def convert_to_wav(audio_path: str) -> str:
"""
Convert audio file to WAV 16kHz mono (optimal for whisper.cpp).
Returns path to WAV file. Skips if WAV already exists.
"""
src = Path(audio_path)
# Already a WAV file, skip
if src.suffix.lower() == ".wav":
return audio_path
WAV_CACHE_DIR.mkdir(exist_ok=True)
wav_path = WAV_CACHE_DIR / (src.stem + ".wav")
# Skip if already converted
if wav_path.exists() and wav_path.stat().st_size > 0:
log.info(f" WAV cache hit: {wav_path}")
return str(wav_path)
ffmpeg = find_ffmpeg()
if not ffmpeg:
log.warning(" ffmpeg not found, using original file (may cause bad transcription)")
return audio_path
log.info(f" Converting to WAV: {src.name} -> {wav_path.name}")
cmd = [
ffmpeg,
"-i", audio_path,
"-vn", # no video
"-acodec", "pcm_s16le", # 16-bit PCM
"-ar", "16000", # 16kHz sample rate (whisper standard)
"-ac", "1", # mono
"-y", # overwrite
str(wav_path),
]
try:
result = subprocess.run(
cmd,
capture_output=True,
text=True,
timeout=300, # 5 min max for conversion
)
if result.returncode != 0:
log.error(f" ffmpeg failed: {result.stderr[:300]}")
return audio_path
log.info(f" WAV ready: {wav_path.name} ({wav_path.stat().st_size / 1_048_576:.0f} MB)")
return str(wav_path)
except FileNotFoundError:
log.warning(f" ffmpeg not found at: {ffmpeg}")
return audio_path
except subprocess.TimeoutExpired:
log.error(f" ffmpeg conversion timeout for {audio_path}")
return audio_path
def load_manifest() -> dict:
with open(MANIFEST_PATH, encoding="utf-8") as f:
return json.load(f)
def save_manifest(manifest: dict):
with open(MANIFEST_PATH, "w", encoding="utf-8") as f:
json.dump(manifest, f, indent=2, ensure_ascii=False)
def transcribe_file(audio_path: str, output_base: str) -> bool:
"""
Run whisper.cpp on a single file.
Returns True on success.
"""
cmd = [
WHISPER_BIN,
"--model", WHISPER_MODEL,
"--language", "ro",
"--no-gpu",
"--threads", str(os.cpu_count() or 4),
"--beam-size", "1",
"--best-of", "1",
"--max-context", "0", # don't carry context between segments (prevents hallucination loops)
"--entropy-thold", "2.4", # reject high-entropy (hallucinated) segments
"--max-len", "60", # shorter segments reduce drift
"--suppress-nst", # suppress non-speech tokens (reduces hallucination on silence)
"--no-fallback", # don't retry with higher temperature
"--output-txt",
"--output-srt",
"--output-file", output_base,
"--file", audio_path,
]
log.info(f" CMD: {' '.join(cmd)}")
try:
# Add whisper.exe's directory to PATH so Windows finds its DLLs
env = os.environ.copy()
whisper_dir = str(Path(WHISPER_BIN).resolve().parent)
env["PATH"] = whisper_dir + os.pathsep + env.get("PATH", "")
result = subprocess.run(
cmd,
stdout=sys.stdout,
stderr=sys.stderr,
timeout=7200, # 2 hour timeout per file
env=env,
)
if result.returncode != 0:
log.error(f" whisper.cpp failed (exit {result.returncode})")
return False
# Verify output exists and is non-empty
txt_path = Path(f"{output_base}.txt")
srt_path = Path(f"{output_base}.srt")
if not txt_path.exists() or txt_path.stat().st_size == 0:
log.error(f" Empty or missing transcript: {txt_path}")
return False
log.info(f" Output: {txt_path.name} ({txt_path.stat().st_size} bytes)")
if srt_path.exists():
log.info(f" Output: {srt_path.name} ({srt_path.stat().st_size} bytes)")
return True
except subprocess.TimeoutExpired:
log.error(f" Timeout (>2h) for {audio_path}")
return False
except FileNotFoundError:
log.error(f" whisper.cpp not found at: {WHISPER_BIN}")
log.error(f" Set WHISPER_BIN env var or put whisper-cli.exe in PATH")
return False
except Exception as e:
log.error(f" Error: {e}")
return False
def parse_module_filter(arg: str) -> set[int]:
"""Parse module filter like '1-3' or '4,5' or '1-3,5' into a set of 1-based indices."""
result = set()
for part in arg.split(","):
part = part.strip()
if "-" in part:
a, b = part.split("-", 1)
result.update(range(int(a), int(b) + 1))
else:
result.add(int(part))
return result
def main():
if not MANIFEST_PATH.exists():
log.error("manifest.json not found. Run download.py first.")
sys.exit(1)
# Parse --modules filter
module_filter = None
if "--modules" in sys.argv:
idx = sys.argv.index("--modules")
if idx + 1 < len(sys.argv):
module_filter = parse_module_filter(sys.argv[idx + 1])
log.info(f"Module filter: {sorted(module_filter)}")
manifest = load_manifest()
TRANSCRIPTS_DIR.mkdir(exist_ok=True)
total = 0
transcribed = 0
skipped = 0
failed = 0
for mod_idx, mod in enumerate(manifest["modules"], 1):
if module_filter and mod_idx not in module_filter:
log.info(f"\nSkipping module {mod_idx}: {mod['name']}")
continue
log.info(f"\n{'='*60}")
log.info(f"Module: {mod['name']}")
log.info(f"{'='*60}")
for lec in mod["lectures"]:
total += 1
if lec.get("download_status") != "complete":
log.warning(f" Skipping (not downloaded): {lec['title']}")
continue
audio_path = lec["audio_path"]
stem = Path(lec["original_filename"]).stem.replace(" [Audio]", "")
output_base = str(TRANSCRIPTS_DIR / stem)
# Check if already transcribed
txt_path = Path(f"{output_base}.txt")
if txt_path.exists() and txt_path.stat().st_size > 0:
lec["transcribe_status"] = "complete"
skipped += 1
log.info(f" Skipping (exists): {stem}.txt")
continue
log.info(f" Transcribing: {lec['title']}")
log.info(f" File: {audio_path}")
# Convert MP3 -> WAV 16kHz mono for reliable whisper.cpp input
wav_path = convert_to_wav(audio_path)
if transcribe_file(wav_path, output_base):
lec["transcribe_status"] = "complete"
transcribed += 1
else:
lec["transcribe_status"] = "failed"
failed += 1
# Save manifest after each file (checkpoint)
save_manifest(manifest)
# Log milestone after first module (no longer pauses)
if mod == manifest["modules"][0] and transcribed > 0:
log.info(f"First module complete ({transcribed} files). Continuing automatically...")
# Validation
empty_outputs = [
lec["title"]
for mod in manifest["modules"]
for lec in mod["lectures"]
if lec.get("transcribe_status") == "complete"
and not Path(lec["transcript_path"]).exists()
]
log.info("\n" + "=" * 60)
log.info(f"Transcribed {transcribed}/{total} files, {skipped} skipped, {failed} failures.")
log.info(f"No empty outputs: {'PASS' if not empty_outputs else 'FAIL'}")
if empty_outputs:
for t in empty_outputs:
log.error(f" Missing transcript: {t}")
log.info("=" * 60)
save_manifest(manifest)
if failed:
sys.exit(1)
if __name__ == "__main__":
main()