mynah 🐦

Local-first transcription for Korean meetings.
Record directly or drop an audio file — get a clean .txt in minutes.
No cloud. No per-meeting cost. Runs entirely on your Mac.

Screenshots

Features

• Transcribes while you record — 60–90 s chunks are cut at natural pauses and transcribed in the background, so the transcript is ready seconds after you stop instead of an hour later
• Survives a crash — audio is written as headerless raw PCM with no close step, so killing the terminal cannot corrupt it. Unfinished sessions are found on the next launch and can be resumed, finished, or discarded
• Apple GPU acceleration — MLX runs Whisper on the Metal GPU at 7.8–10.9× realtime, against 0.86× on the CPU path. Falls back automatically off Apple Silicon
• Automatic gain correction — quiet recordings are the single largest cause of Whisper hallucination loops; input is normalized to −18 dBFS before transcription (the archived audio keeps its original level)
• Or drop an existing file — m4a, mp3, wav, flac, webm, mp4 supported
• Korean-first — Whisper large-v3, fixed ko language, VAD always on to prevent hallucinations on silence
• English code-switching — three-layer defense (initial_prompt + hotwords + post-process replacements) keeps project names and technical terms intact
• Speaker diarization — SPEAKER_01: labels per segment (optional, requires HF token)
• Word-level timestamps — [HH:MM:SS] prefix per segment (optional)
• Denoising — Demucs vocals stem strips HVAC and keyboard noise (optional)
• Glossary & replacements — editable inside the TUI; glossary fed into Whisper as context and hotwords
• TUI for daily use, CLI for scripting — both first-class, same pipeline
• System health check — mynah --doctor verifies all dependencies and shows actionable fixes
• Offline, always — no API calls after the first model download (~3 GB, one-time)

Output formats

Output filename: <input>.txt. On collision: <input> (1).txt, <input> (2).txt, etc. — never silently overwrites.

Install

Prerequisites

⚠️ Python 3.13+ is not yet supported — the ML stack (torch, torchaudio, ctranslate2) does not have stable wheels for 3.13+.

One-line install

pipx install mynah-stt

# Optional: with denoising (Demucs) support
# pipx install 'mynah-stt[denoise]'

# Optional: speaker diarization needs a free HuggingFace token
mynah --setup

Package vs. command name: the PyPI distribution is mynah-stt, but the CLI you actually run is mynah (and Python imports are import mynah). The -stt suffix only shows up at install time — same pattern as pip install Pillow → import PIL.

First run: Whisper large-v3 (~3 GB) downloads automatically on the first transcription and is cached for all subsequent runs.

Quick start

mynah                               # open TUI → Record → Stop → transcript ready
mynah meeting.m4a                   # CLI: transcribe existing file
mynah meeting.m4a --diarize         # with speaker labels
mynah meeting.m4a --timestamps      # with time codes
mynah --doctor                      # check system dependencies

TUI

Run mynah with no arguments to open the TUI.

Main screen — press R or Space to start recording, F to open an existing audio file, S for settings, G for glossary, Q to quit.

Recording screen — microphone captures at 16 kHz mono. The level meter shows live input amplitude, and transcribed text appears in the panel below as each chunk finishes. Space to pause/resume, S to stop, Esc to cancel and discard.

Recovering an unfinished session — if mynah was killed mid-recording, the main screen shows a banner. Press U to resume recording into the same session, finalize what was captured, or discard it. Nothing is deleted until you confirm twice.

Settings (S from anywhere) — toggle speaker diarization, word-level timestamps, and denoising with on/off switches; switch the Whisper model and input language; set your HuggingFace token inline without leaving the TUI.

Result screen — transcript is auto-copied to the clipboard the moment it appears. Open the file or reveal it in Finder directly from this screen.

CLI

mynah <audio_file> [flags]

Glossary — the biggest quality lever

Add the project names, people, and technical terms that appear in your meetings. mynah feeds them to Whisper as context (initial_prompt + hotwords), which keeps code-switched proper nouns in their original form.

# Edit from the TUI (G key) or directly:
~/.config/mynah/glossary.txt   # one term per line

Example entries: Whisper, Slack, Q3 OKR, 홍길동, CTranslate2

Replacements (safety net)

Post-processing find/replace rules for known mistakes:

# ~/.config/mynah/replacements.toml
[[rule]]
from = "슬랙"
to = "Slack"

[[rule]]
from = "위스퍼"
to = "Whisper"

Set regex = true on any rule to use Python regex syntax.

Configuration files

Recording sessions

Each recording gets its own folder under ~/Documents/mynah-recordings/:

2026-08-12-145934/
├── audio.pcm         raw 16 kHz mono, appended as you speak — no header to corrupt
├── transcript.jsonl  one line per finished chunk
├── session.json      options + status
├── meeting.wav       written when the session is finalized
└── meeting.txt       the transcript

audio.pcm deliberately has no header. A WAV header stores the total length and can only be written when the file is closed, so a process killed mid-recording leaves an unreadable file. Headerless PCM is valid at every instant, and the header is added afterwards from the file size — the same code path for a normal stop and for a crash recovery.

Performance

Measured on a MacBook Pro M5 with large-v3, on real Korean meeting audio.

CPU inference is slower than the recording itself, which is why a one-hour meeting used to mean an hour of waiting. On the GPU path the transcription keeps pace with the microphone, so a chunk is finished long before the next one is recorded and the wait after you press stop is a few seconds.

Dropping int8 quantization along with the CPU makes the GPU path both faster and more accurate — quantization was a compromise the CPU forced.

Speaker diarization is the exception. It needs word-level timestamps and global speaker clustering across the whole meeting, neither of which per-chunk transcription produces, so enabling it re-runs the full file pipeline after recording ends. Expect a wait proportional to the meeting length.

Check which backend you are actually on:

mynah --doctor        # reports backend, model, and last input level

Troubleshooting

Run the built-in health check first:

mynah --doctor

Common issues and fixes:

Development

git clone https://github.com/rlawjdghksdlqslek/mynah-stt.git
cd mynah-stt

# Install with dev extras (editable mode — code changes take effect immediately)
pipx install -e '.[dev]'

# Unit tests — no model download required
pytest tests/

# Lint
ruff check .

mynah/core/ and mynah/config/ have no UI dependencies; the TUI and CLI are thin wrappers over them. ML packages are imported lazily inside the functions that need them, so the whole test suite runs without downloading a model.

mynah/
├── core/
│   ├── session.py    # session folder, raw PCM, JSONL, crash recovery
│   ├── live.py       # chunk transcription worker + hallucination guard
│   ├── record.py     # mic capture, silence-based chunk boundaries
│   ├── audio.py      # ffmpeg normalize + gain correction
│   ├── transcribe.py # MLX / WhisperX backend dispatch
│   └── pipeline.py   # file pipeline + session finalization
├── config/           # settings, glossary, replacements (no ML deps)
├── tui/              # Textual app + screens
└── app.py            # dispatches TUI vs CLI based on argv

There are two pipelines. Live recording streams PCM to a session folder while a worker transcribes silence-cut chunks into transcript.jsonl; finalize_session() renders it and wraps the audio into a WAV. File input (pipeline.run()) is the original path: normalize, optional denoise, whole-file transcribe, optional diarize, render.

MLX has no beam search, and beam search is what suppressed Whisper's repetition loops on the CPU path. core/live.py therefore checks each chunk for a loop and retries it through WhisperX with beam_size=5, falling back to an explicit gap marker rather than writing garbage or dropping audio silently.

License

Apache-2.0. See LICENSE.

Acknowledgments

• OpenAI Whisper — speech recognition model
• MLX — Apple Silicon array framework
• mlx-whisper — Whisper on the Metal GPU
• WhisperX — alignment + diarization wrapper
• faster-whisper — CTranslate2-accelerated Whisper inference
• pyannote-audio — speaker diarization
• Textual — TUI framework
• Demucs — audio source separation