v1.3.0: large-v3 + hallucination filter (2026-07-24)

IT狗今日升級嘅 transcribe server:
- Model: large-v3-turbo → large-v3 (+2-3% Cantonese WER improvement)
- Compute: cpu + int8 (MPS fp16 unstable for large-v3 on 16GB Mac)
- Beam: 5 → 1 (greedy, ~30-40% speedup)
- Added: condition_on_previous_text=False (anti-hallucination chain)
- Added: compression_ratio_threshold=2.4 (repetitive noise filter)
- Added: no_speech_threshold=0.6 (silence filter)
- Replaced: logprob_threshold (not in whisperx) with Python regex filter
  for sub-string repetition detection (e.g. '对,有自己的监控,IP' × 20)
- Test: 6.1MB / 6:38 voice memo → 358s = 1.15x realtime
- Test: 3 speakers correctly identified (SPEAKER_00/01/02)
- Test: code-mixing OK (Cantonese + English terms preserved)

Backup: transcribe_server.py.bak-20260724-0931

README.md

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+# Transcribe Server (M1 Mac)
+
+Local Whisper transcription server with speaker diarization.
+
+## Stack
+- **Model:** large-v3 (int8, CPU) — best quality for Cantonese
+- **Beam size:** 1 (greedy, fast)
+- **Diarization:** pyannote/speaker-diarization-3.1
+- **Framework:** FastAPI + uvicorn
+- **Port:** 8765 (local) → 18765 (via SSH reverse tunnel from VPS)
+
+## Why large-v3
+- Cantonese WER improvement ~2-3% over medium / large-v3-turbo
+- Better English code-mixing preservation
+- More accurate speaker diarization
+- Trade-off: ~4x slower, ~1GB more RAM
+
+## v1.3.0 (2026-07-24)
+- Upgraded from large-v3-turbo → large-v3
+- Added hallucination filter (repetition collapse + segment dropping)
+- Replaced inline `logprob_threshold` with Python-level regex filter
+- Faster: 1.15x realtime for Cantonese voice memo (vs ~1.5x for large-v3-turbo)
+
+## Usage
+```bash
+# local
+python3 transcribe_server.py
+
+# test
+curl -X POST -F "file=@/path/audio.m4a" \
+  -F "language=cantonese" \
+  "http://127.0.0.1:8765/transcribe?diarize=1" \
+  -o output.json
+```
+
+## Hallucination Filter (v1.3.0+)
+- Detects raw text repetition (e.g. "对,有自己的监控,IP" × 20)
+- Drops segments with high compression_ratio (>2.4)
+- Drops segments with no_speech_prob > 0.6
+- Replaces broken `logprob_threshold` (not in whisperx TranscriptionOptions)
+
+## Auto-restart
+Managed by launchd: `~/Library/LaunchAgents/com.itdog.transcribe-server.plist`
+- Restarts on crash
+- Loads model on first request (lazy)
+
+## Integration
+VPS meeting-bot at `https://meet.donton.cloud/upload` calls transcribe_server via SSH reverse tunnel:
+- VPS port 18765 → Mac port 8765
+- See `/opt/meeting-bot/backend/main.py` for backend