rusty_link

rusty_link is a Rust wrapper for Ableton Link through the official C 11 wrapper extension, abl_link. This library attempts to be mostly unopinionated and plain in copying the functionality of abl_link, while providing some of Rust's safety guarantees.

Ableton Link is a technology that synchronizes musical beat, tempo, phase, and start/stop commands across multiple applications running on one or more devices. Applications on devices connected to a local network discover each other automatically and form a musical session in which each participant can perform independently: anyone can start or stop while still staying in time. Anyone can change the tempo, the others will follow. Anyone can join or leave without disrupting the session.

Examples

To run the examples, clone this repository and change into its directory. Then fetch the Ableton Link source by initializing the git submodules with:

git submodule update --init --recursive

link_hut_silent: A Rust port from C of the simple 'LinkHut' example without sound by Ableton. To run it:

cargo run --release --example link_hut_silent

link_hut: A Rust port from C++ of the more complex 'LinkHut' example with sound by Ableton. Run it like this:

cargo run --release --example link_hut

See the cpal documentation for ASIO and Jack support, if required.

Requirements

Requires a recent version of CMake (3.14 or newer) to be installed and available in your terminal. Test with cmake --version.

Linux may require a few more system libraries to be installed for C compilation, depending on your distro, like build-essential, libclang-dev or libasound2-dev and pkg-config for examples, etc...

Thread and Realtime Safety

'abl_link.h' has doc comments about thread and realtime safety on some of its functions. Those comments have been copied to the functions of this library. A short explainer on what they mean:

• Thread Safety: Thread-safe code only manipulates shared data structures in a manner that ensures that all threads behave properly and fulfil their design specifications without unintended interaction.

• Realtime Safety: These functions can be called in a Realtime environment without blocking the thread. For example, the audio thread/callback.

Implementation

• rusty_link currently wraps around all functions available in 'abl_link.h' and makes them publicly available as methods on either the AblLink or the SessionState struct, except for the destructors, which are implemented on the Drop trait.
• An instance of AblLink can be thought of as an Object with internal mutability. Thread safety is guaranteed in all functions, except for the capture/commit of Session States, with internal Mutexes on the C++ side. Check the function doc comments and official Link documentation for more.
• Includes a Rust port of the C++ HostTimeFilter, which can be used in the audio callback to align the host clock with the sample clock.
• Delete functions have been added to delete previously set num_peers, start_stop and tempo callbacks.

Testing

Ableton designed a Test Plan to test if your implementation of Ableton Link in your project meets all the expected requirements.

Tested Platforms

rusty_link itself works on all major platforms. I only had trouble with the example with sound on Linux. Could be my fault for not using cpal properly?! Any help with that is appreciated 😘. Anyway, this shouldn't stop anyone from using this library in their project. Have fun!

Changelog

Release notes can be seen on the project GitHub page here.

Feedback

I am not a professional Developer, just doing this as a hobby, so any help with updates and corrections of my work are welcome.

License

Ableton Link is dual licensed under GPLv2+ and a proprietary license.

This means that rusty_link has to be under the GPLv2+ as well.

If you would like to incorporate Link into a proprietary software application, please contact Ableton at link-devs@ableton.com.

Credits

Thanks to Magnus Herold for his implementation. I made this library to learn about FFI in Rust and I started it as a fork of his, but then pivotted to using the offical C wrapper by Ableton.

Some code for splitting closures has been borrowed from ffi_helpers with altered functionality. Thanks to Michael F Bryan for his work. Pull request to ffi_helpers pending...