Paulstretch For Live — Ableton Live extension

This is an experimental program for extreme stretching the audio.

Embeds libpaulstretch — a modern C++ rewrite of paulstretch — as an Ableton Live extension.

See also Paulstretch For Web

Just want to use it?

Extensions are a new feature in Ableton Live 12.4.5 (Suite), currently in beta. They won't work in previous versions.

Grab the prebuilt Paulstretch-<version>.ablx from this repo's Releases and install it into Live (Preferences → Extensions). You don't need any of the build steps below.

Building from source

This extension depends on the Ableton Extensions SDK (@ableton-extensions/sdk and @ableton-extensions/cli), which is not yet published to npm. package.json references both as local tarballs under vendor/:

"@ableton-extensions/sdk": "file:./vendor/ableton-extensions-sdk-<version>.tgz"  // dependency
"@ableton-extensions/cli": "file:./vendor/ableton-extensions-cli-<version>.tgz"  // devDependency

So before npm install will work you have to drop those two tarballs into vendor/ yourself.

1. Get the SDK and CLI in place

Download the Extensions SDK zip (e.g. extensions-sdk-<version>.zip) from the Extensions SDK site and unzip it. Inside you'll find two tarballs:

ableton-extensions-sdk-<version>.tgz
ableton-extensions-cli-<version>.tgz

Copy both into a vendor/ folder at the root of this repo:

mkdir -p vendor
cp /path/to/ableton-extensions-sdk-<version>.tgz vendor/
cp /path/to/ableton-extensions-cli-<version>.tgz vendor/

The filenames must match the file:./vendor/… paths in package.json exactly (they carry the version).

2. Install dependencies

npm run install:all   # installs the host, then src/dialog

3. Build and package

npm run build       # vite-build the dialog + esbuild the host
npm run package     # produce Paulstretch-<version>.ablx

4. Run

npm start

opens Ableton Live against the local build (Live must have Developer Mode enabled in Preferences → Extensions).

Dev tips

• npm run dev:ui — run the dialog standalone in Vite for UI iteration. In standalone mode the file menu / drag-drop are active; the Apply bar is hidden.
• The dialog detects "host mode" by checking whether window.__INITIAL_DATA__ contains real values (vs the placeholder text from index.html).
• The .ablx packager includes the entire Vite-built dist/dialog/ tree as runtime assets (see package.js's ABLX_INCLUDES).

License

Paulstretch For Live is licensed under the GPL v2.0

The bundled dialog ships two fonts, each under the SIL Open Font License 1.1. Their license texts are included both in this repo and inside every .ablx, under src/dialog/public/licenses/ → dist/dialog/licenses/:

• Inter — © The Inter Project Authors — Inter-LICENSE.txt
• JetBrains Mono — © The JetBrains Mono Project Authors — JetBrainsMono-LICENSE.txt

libpaulstretch is also GPL v2.0

Credits

Paulstretch For Live. Copyright Oliver Larkin 2026.

Based on Paulstretch by Nasca Octavian Paul.