Groove Transplant

An Ableton Live extension that extracts the timing and velocity "feel" of a MIDI or audio clip and stamps it onto other MIDI clips — and builds playable Drum Racks by slicing the individual drum voices out of an audio loop.

What it does

Producers often have one clip that grooves — a drummed hi-hat pattern, a humanized bassline, a sampled break — and want everything else in the session to lock to that same pocket. Groove Transplant analyses a source clip, measures how far each hit sits ahead of or behind the grid and how its velocity varies, and saves that as a reusable groove profile. You can then apply it to any MIDI clip with adjustable timing and velocity strength, previewing the result before committing it as a single undo step. Extracted grooves are also written out as native Live .agr files so they show up in Live's browser and can be dragged straight into the Groove Pool.

It also goes the other direction with audio: point it at a drum loop and it detects the kick, snare, hi-hat and open-hat hits, slices each voice into its own WAV, and assembles a Drum Rack on a fresh MIDI track — turning a one-shot loop into a fully playable kit.

Usage

All actions are reached by right-clicking an object in Live. The exact context-menu labels and the object types they appear on:

Object type	Menu item	What happens
MIDI clip	Copy Groove	Detects the optimal grid resolution, extracts per-slot timing and velocity offsets, and opens a dialog with a bar chart, a resolution override, and a name field. Save stores the profile and exports a .agr to the Groove Pool.
MIDI clip	Apply Groove…	Opens a picker of saved grooves with Timing strength and Velocity strength sliders and a live before/after preview. Apply rewrites the clip's notes in one undo step. You can also delete a groove from this dialog, which reopens it with the updated list.
Audio clip	Extract Groove from Audio…	Reads the audio file, estimates BPM (from the clip/file name or by analysis), then shows a settings dialog (BPM, frequency band, sensitivity, resolution). Detects transients, builds a groove, and lets you save/export it as .agr.
Audio clip	Build Drum Rack from Audio…	Shows a settings dialog (BPM, sensitivity, which voices to detect, track name, fill-gaps). Detects drum voices, slices them to WAV, and creates a new MIDI track with a Drum Rack.
Audio track	Manage Drum Rack Samples…	Lists previously-created drum rack sample sets with size and date; select sets and delete them from disk. (The handler ignores the clicked track — it is surfaced here purely so the action is discoverable.)

Audio commands accept WAV and AIFF (PCM 16-bit or 24-bit) only; MP3/AAC and 32-bit/compressed formats are rejected.

Where files go

• Exported grooves: ~/Music/Ableton .../User Library/Grooves/Groove Transplant/<name>.agr
• Drum rack sample sets: ~/Music/Ableton .../User Library/Samples/Groove Transplant/<loop name>/
• Internal groove profiles (JSON): the extension's storageDirectory.

A groove profile records offsets (per-slot timing deviations in beats), velocityOffsets (per-slot velocity deviation, –1..+1), plus resolution, swingAmount, tempo, name, id, and createdAt.

Requirements

• A build of Ableton Live whose Extension Host negotiates Extensions API 1.0.0, with Developer Mode enabled (Live → Preferences → Extensions).
• The Ableton Extensions SDK (@ableton-extensions/sdk), which is proprietary and not bundled here — see ../BUILDING.md for how to obtain and place it.

Build & install

From the repo root:

pnpm install
pnpm run build

Then deploy this extension into your Live User Library:

cd groove-transplant && pnpm run deploy

deploy rebuilds the bundle and copies dist/extension.js plus manifest.json into your Ableton Extensions/ folder. See ../BUILDING.md for full prerequisites, the SDK setup, and per-extension build details.

Development

After editing source, run pnpm run deploy again and reload the running Extension Host via the dev-launch workflow described in ../DEVELOPMENT.md. A bare pnpm run build is not enough on its own — the Extension Host only loads the deployed copy in your User Library, so you must deploy before reloading.

Limitations / notes

• Audio extraction and slicing support WAV/AIFF PCM 16-bit or 24-bit only; 32-bit int PCM and compressed AIFF are rejected with an error.
• At very high tempos (200 BPM+), tightly-spaced drum hits (16th-note doublets) may occasionally be merged by the transient deduplication pass.
• Building a Drum Rack does not roll back partial state: if a voice fails to load, an orphan MIDI track can be left in Live.
• The Apply Groove dialog previews timing/velocity visually but does not play back audio.
• CC/automation grooves are out of scope — this extension works on note timing and velocity only.

License

GPL-3.0-or-later.