# Rust bindings for Oboe library
[](https://github.com/katyo/oboe-rs)
[](https://crates.io/crates/oboe)
[](https://docs.rs/oboe)
[](https://opensource.org/licenses/Apache-2.0)
[](https://github.com/katyo/oboe-rs/actions?query=workflow%3ARust)
Safe Rust interface for [Oboe](https://github.com/google/oboe) High-Performance Audio library for Android.
Also it provides interface for some platform APIs significant to Audio IO.
__Oboe__ is a C++ library which makes it easy to build high-performance audio apps on Android. It was created primarily to allow developers to target a simplified API that works across multiple API levels back to API level 16 (Jelly Bean).
## Crate features
- __java-interface__ Add interface for some Android platform APIs.
- __generate-bindings__ Generate bindings at compile-time. By default the pregenerated bindings will be used.
- __compile-library__ Compile _oboe_ C++ library at compile-time using __cmake__. By default the precompiled library will be used.
- __shared-link__ Use shared linking. By default the static Oboe libarary will be used.
The crate already has pregenerated bindings and precompiled static libraries for the following Android targets:
- __armv7__
- __aarch64__
- __i686__
- __x86_64__
## Build issues
The **[clang-sys](https://crates.io/crates/clang-sys)** crate uses **[llvm-config](http://llvm.org/docs/CommandGuide/llvm-config.html)** for searching [libclang](https://clang.llvm.org/docs/Tooling.html) library and preparing _C_/_C++_ compiler configuration. In order to get proper setup you should add *llvm-config* to your executables search path.
In case of using tools with libclang under the hood like __bindgen__ you must be sure in proper your setup. Otherwise you get an errors related to missing headers or definitions.
To build applications you need recent version of __cargo-apk__, which supports latest Android [SDK](https://developer.android.com/studio#command-tools) (28+) and [NDK](https://developer.android.com/ndk) (20+). Don't forget to set ANDROID_SDK_ROOT environment variable with paths to installed SDK.
For building host crates which requires C-compiler you may also set __HOST_CC__ environment variable with path to your C-compiler.
## Usage example
Playing sine wave in asynchronous (callback-driven) mode:
```rust
use oboe::{
AudioOutputCallback,
AudioOutputStream,
AudioStreamBuilder,
DataCallbackResult,
PerformanceMode,
SharingMode,
Mono,
};
// Structure for sound generator
pub struct SineWave {
frequency: f32,
gain: f32,
phase: f32,
delta: Option<f32>,
}
// Default constructor for sound generator
impl Default for SineWave {
fn default() -> Self {
Self {
frequency: 440.0,
gain: 0.5,
phase: 0.0,
delta: None,
}
}
}
// Audio output callback trait implementation
impl AudioOutputCallback for SineWave {
// Define type for frames which we would like to process
type FrameType = (f32, Mono);
// Implement sound data output callback
fn on_audio_ready(&mut self, stream: &mut dyn AudioOutputStream, frames: &mut [f32]) -> DataCallbackResult {
// Configure out wave generator
if self.delta.is_none() {
let sample_rate = stream.get_sample_rate() as f32;
self.delta = (self.frequency * 2.0 * PI / sample_rate).into();
println!("Prepare sine wave generator: samplerate={}, time delta={}", sample_rate, self.delta.unwrap());
}
let delta = self.delta.unwrap();
// Generate audio frames to fill the output buffer
for frame in frames {
*frame = self.gain * self.phase.sin();
self.phase += delta;
while self.phase > 2.0 * PI {
self.phase -= 2.0 * PI;
}
}
// Notify the oboe that stream is continued
DataCallbackResult::Continue
}
}
// ...
// Create playback stream
let mut sine = AudioStreamBuilder::default()
// select desired performance mode
.set_performance_mode(PerformanceMode::LowLatency)
// select desired sharing mode
.set_sharing_mode(SharingMode::Shared)
// select sound sample format
.set_format::<f32>()
// select channels configuration
.set_channel_count::<Mono>()
// set our generator as callback
.set_callback(SineWave::default())
// open the output stream
.open_stream()
.unwrap();
// Start playback
sine.start().unwrap();
// ...
```