121 lines
6.0 KiB
Markdown
121 lines
6.0 KiB
Markdown
# Blurt
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Tray-based push-to-talk voice-to-text for Linux and Windows. Toggle recording
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with a hotkey, speak, toggle off — Blurt transcribes the clip and copies the
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text to your clipboard.
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If a transcript starts with `to my agent`, the rest is dispatched as an agent
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task instead of copied.
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## Setup
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Requires [uv](https://docs.astral.sh/uv/) and Python 3.11+.
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```sh
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uv sync
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```
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### API key
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Blurt reads the key for its current model's provider in this order:
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environment variable → OS keyring → local file.
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| Provider | Env var | Keyring (`service` / `user`) | File |
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|------------|----------------------|---------------------------------|----------------------|
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| OpenAI | `OPENAI_API_KEY` | `openai-api-key` / `felixm` | `api_key.txt` |
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| OpenRouter | `OPENROUTER_API_KEY` | `openrouter-api-key` / `felixm` | `openrouter_key.txt` |
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Key files and runtime config stay local (gitignored).
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## Running
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**Linux** — `uv run blurt` starts the tray icon. Bind a hotkey to
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`./blurt-toggle`, which signals the running instance to start/stop recording.
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**Windows** — launch `blurt.vbs` (runs Blurt with no console window). The
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global hotkey is **F20**.
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## Configuration
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Set from the tray menu, or via files / env vars:
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- **Model** — `model.txt` / `BLURT_TRANSCRIPTION_MODEL`. For lowest latency use
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`openai/whisper-large-v3-turbo` (OpenRouter, served by Groq).
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To use [Microsoft MAI-Transcribe 2](https://openrouter.ai/microsoft/mai-transcribe-2),
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select **OpenRouter: MAI-Transcribe 2** from the tray menu or set
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`BLURT_TRANSCRIPTION_MODEL=microsoft/mai-transcribe-2`. Requires an OpenRouter API key.
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- **Language** — `language.txt` / `BLURT_TRANSCRIPTION_LANGUAGE` (`en`, `de`).
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- **Input device** — tray menu (persisted by name in `device.txt` /
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`BLURT_INPUT_DEVICE`). Pick an explicit mic: PortAudio device indices shift
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when USB gear comes and goes, and the OS default source can change under you.
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The menu hides playback endpoints and raw ALSA `hw:` devices that the sound
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server already owns; `BLURT_INPUT_DEVICE` can still name one directly.
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Devices that refuse 16 kHz (raw ALSA and PipeWire's JACK endpoints do) are
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captured at their native rate and resampled.
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By default, Blurt transcribes while you speak. It conditions the incoming audio,
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then seals and uploads phrases as pauses provide natural boundaries. A chunk is
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at least about 8 seconds long; early cuts require roughly 800 ms of quiet, while
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the required pause falls towards 500 ms as the chunk approaches the 20-second
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target. After 45 seconds it uses the quietest recent point even without a full
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pause, so one uninterrupted passage cannot hold up the whole recording. Pause
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detection follows the microphone's noise floor and only skips near-digital
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silence; ordinary quiet speech and the silence around phrase boundaries remain
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in the audio.
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Up to three chunks are transcribed concurrently. Their results are retained by
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position and delivered once, in recording order, after you stop and the final
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chunk finishes. Starting another recording does not mix the two sessions, and
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each session keeps the model, language, provider, and API key selection it had
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when recording began even if you change the tray settings meanwhile. The tray
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icon shows progress as chunks finish.
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While recording, the red icon brightens and its three level bars rise with
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microphone volume, settling back down during pauses. This shows incoming audio
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activity; it does not indicate that the transcription service has recognized words.
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Each session has a recovery directory under `spool/` (gitignored). Sealed chunks,
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completed text, and a checkpoint of the unsealed tail are kept there until the
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complete transcript reaches the clipboard or agent. The tail is checkpointed
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about once a second; an abrupt crash can lose audio since the last checkpoint.
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**Retry failed transcriptions (N)** re-uploads unfinished chunks and reconstructs
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the saved recording, including text that succeeded before a network error,
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timeout, server error, or empty response. A partial result is copied with ` […] `
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and retained for retry; retried results are
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copied rather than dispatched to an agent. The upload timeout scales with each
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chunk: 30 seconds plus 30 seconds per minute of audio, capped at five minutes.
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Set `BLURT_STREAMING=0` before starting Blurt to use the legacy whole-clip flow.
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That mode trims up to 150 ms of stream-open click, filters DC bias, normalises
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towards -20 dBFS, and rejects near-silent clips. It spools the complete clip
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before upload, splits recordings longer than five minutes near pauses into
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roughly four-minute parallel uploads, retains retryable failures, and marks
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missing chunks with ` […] `. Rejected requests (4xx other than 408 and 429) are
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discarded because retrying the same request cannot fix them.
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If a transcript comes back missing words, check `blurt.log`; streaming mode logs
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chunk boundaries, noise floor, and `dead=`, the longest run of digital silence
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per chunk, plus the time from Stop to delivery. A non-zero `dead=` can indicate
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an input dropout. Pinning an
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input device avoids the system default moving between sources. In legacy mode,
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set `BLURT_SAVE_CAPTURES=1` (or to a directory) to retain raw and uploaded WAVs
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and hear exactly what the API received.
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## Checking the microphone
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`uv run mic_check.py [device] [seconds]` records from Blurt's configured input,
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prints levels before and after conditioning, saves the WAV it would have
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uploaded, and transcribes it with the current model. Use it when transcripts
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come back wrong: bad audio shows up as a DC bias, clipping, or a speech level
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far below -30 dBFS.
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Logs are written to `blurt.log` in your temp directory (openable from the tray
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menu).
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## Moving to another machine
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`uv run export.py` writes a zip of just the source (no 200 MB+ `.venv`, no
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caches, no key files) to your temp directory. It's pure Python, so it runs the
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same on Linux and Windows — no shell needed — and it only reads, so it's safe
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while Blurt is recording. Unzip on the other machine and `uv sync` to rebuild
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`.venv` for that OS. (Or simply `git clone` the repo fresh.)
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