Rust Audio Engine

An audio engine implemented in Rust, designed for use in professional audio applications such as DAWs. (WIP)

Overview of Each Crate

• audio_engine_cdylib: Defines the C API for using audio_engine_service from other languages. Required for running example_app_flutter.
• audio_engine_core: Implements core logic and models such as the Audio Graph.
• audio_engine_plugin: Integrates audio_engine_core with nih_plug, allowing CLAP plugins to be built.
• audio_engine_service: Connects audio_engine_core with audio devices, making sound output possible. Can be run as a standalone service.
• example_app_flutter: An example of integrating audio_engine_cdylib with Flutter.
• example_app_tauri: An example of integrating audio_engine_service with Tauri.

Prerequisites

Installing portaudio

This project depends on the portaudio library via the audio_engine_service crate. (However, audio_engine_plugin does not depend on it, so if you only need that, you can skip this section.) The rust-portaudio crate should automatically build and install portaudio, so no manual steps should be necessary.

However, as of March 2025, this automatic build seems to fail on macOS. There are two possible workarounds:

1. Install portaudio via Homebrew.

   This is the easier method, but it does not produce a universal binary.

   brew install portaudio

2. Build portaudio from source.

   The issue appears to be fixed in the master branch on GitHub, so you can clone and build it manually. This allows you to build a universal binary. After building, place the library in /usr/local/lib, where rust-portaudio should be able to find it.

Testing

cargo test --workspace

Building and Installing audio_engine_plugin

Run the following command to build audio_engine_plugin and copy it to the user's CLAP installation directory.

./build_and_install_plugin.sh

Running audio_engine_service

This will produce sound output.

cargo run --package audio_engine_service

Running example_app_flutter

Before running, audio_engine_cdylib must be built. If it is not built yet, run the following command:

cargo build --package audio_engine_cdylib

After building, edit main.dart to set the correct library path.

// Set the library path according to the platform.
const libPath =
'../target/debug/libaudio_engine_cdylib.dylib'; // Library file for macOS

Then, run example_app_flutter.

cd example_app_flutter
flutter run

For example, to run it on a macOS device, use:

flutter run -d macos

Running example_app_tauri

cd example_app_tauri
bun tauri dev

Unimplemented Features

Below is a list of major unimplemented features. Other functionalities necessary for building a professional audio application may also be needed.

Plugin Hosting

Support for hosting CLAP plugins. This repository might be useful as a reference: https://github.com/prokopyl/clack/tree/main/host/examples/cpal

Consideration for example_app_flutter:

Currently, audio_engine_service::init is called from Dart's UI thread, but to support CLAP GUI display, it may need to be called from the platform's main thread.

Editing the Playback Graph

Allow adding and removing nodes and edges in the AudioGraph even while accessing it from the real-time thread. For a lock-free implementation, it may be necessary to use something like ArcSwap to swap the graph.

Event Sequencing

Functionality to place audio regions and MIDI clips on a timeline for playback.

MIDI IO

This library might be a good option: https://github.com/Boddlnagg/midir

iOS Support

Porting portaudio to iOS may be challenging (not yet confirmed). In that case, it may be better to use AudioToolbox or similar to connect AudioIO with audio_engine_core.

Multiple Audio Buses

Support for sidechain inputs and multi-output instruments.

Notice

This is an auto-generated document. README_JA.md is the original version.