midifier
Turns a song into a multi-track General MIDI file. It works out which instruments are playing,transcribes each one, and names and assigns the tracks, so the result can be practised againstin kinesthesia.
Available as a REST API and as MCP tools.
Run it
uv sync --extra dev
uv run python -m midifier # API on :8000, docs at /docs
uv run python -m midifier mcp # MCP server
No configuration is needed to start; results are written to ./data.
Use it
# start a transcription
curl -F '[email protected]' http://localhost:8000/v1/jobs
# {"id":"...","state":"queued"}
# poll it
curl http://localhost:8000/v1/jobs/<id>
One job runs at a time, and each takes roughly three times the length of the song, so jobs arepolled rather than waited on. While a job waits, GET /v1/jobs/<id> reports queue_ahead andeta_seconds, and GET /v1/queue reports how busy the service is. The estimate is measured fromcompleted jobs rather than configured, so it reflects whatever hardware this runs on.
The OpenAPI schema is at /openapi.json.
Secure it
The service holds only the hash of an API key, so reading the deployed secret does notlet anyone call it. Generate a pair:
uv run python -m midifier keygen
Deploy the hash as MIDIFIER_API_KEY_HASH, and give the key to callers. With no hashconfigured the service is open, which suits local use.
Callers present the key one of three ways, whichever their client makes easiest:
| caller | how |
|---|---|
| REST | X-API-Key: <key> |
| MCP over HTTP | X-API-Key: <key> or Authorization: Bearer <key> |
| MCP over stdio | the api_key tool argument |
The MCP server is served from the same app at /mcp, so one URL and one key cover bothsurfaces, and a job started over MCP is visible over REST.
Configure it
Every setting is an environment variable prefixed MIDIFIER_. See.env.example for the full list. The ones that matter:
| variable | default | |
|---|---|---|
MIDIFIER_API_KEY_HASH |
unset | when set, callers must present the key |
MIDIFIER_STORAGE_BACKEND |
local |
local or s3 |
MIDIFIER_MINIO_BUCKET |
— | with the other MINIO_* values, for s3 |
MIDIFIER_MODEL_SIZE |
medium |
small, medium or large |
MIDIFIER_HF_TOKEN |
— | needed to download the transcription weights |
MIDIFIER_MAX_DURATION_SECONDS |
360 |
longest song accepted |
MIDIFIER_MAX_CONCURRENT_JOBS |
1 |
transcriptions run at a time |
Develop it
uv run pre-commit run --all-files # everything CI runs
uv run pytest --cov # tests, 80% gate
Conventions and the reasoning behind the pipeline are in AGENTS.md.
Licence
MIT. The transcription weights it downloads are licensed separately and are not redistributedhere.
