rusty_link

rustylink is a Rust wrapper of abllink, which is a C 11 extension for Ableton Link, provided by Ableton. 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

This crate includes a Rust port from C of the simple 'LinkHut'. To run it:

cargo run --release --example link_hut_silent

There is also a Rust from C++ port of the more complex 'LinkHut', which has sound. 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.

Safety

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 fulfill their design specifications without unintended interaction.

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

Testing

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

Implementation

• rustylink currently wraps around all functions available in 'abllink.h' and makes them publicly available, except for the destructors, which are implemented on the Drop trait.
• Functions have been implemented as methods on either the AblLink or the SessionState struct.
• An instance of AblLink can be thought of as an Object with internal mutability. Kind of like a RefCell. 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 and Link documentation for more.
• The create functions for abllink and sessionstate have been renamed to new to make the API more Rust-intuitive.
• Includes a Rust port of the Ableton Link HostTimeFilter, which can be used in the audio callback to align the sample clock to the host clock. See the link_hut example for details.
• Delete functions have been added to delete previously set num_peers, start_stop and tempo callbacks.
• The Example with sound has been implemented with cpal for cross-platform audio support.

Feedback

I am not a professional Developer or expert in C++ or Rust, 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.

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

Links

For anyone interested, I also started making a multi-platform Ableton Link wrapper for Flutter, called f_link.