broaudio

A real-time audio engine library in C++20, built on SDL3 with a lock-free, audio-thread-safe design. It covers synthesis, sample playback, streaming sources, effects, spatial audio, MIDI, audio-file decode and encode, system-audio capture, and a hierarchical mixing bus.

Documentation

Document	Contents
Features	Full capability list by subsystem
Architecture	Signal flow, threading model, producer paths
Building	Requirements, CMake options, tests, coverage

Engine (include/broaudio/engine.h) is the primary entry point. Per-call contracts, including threading rules and clamping, are documented in the headers.

Quick start

#include <broaudio/engine.h>

broaudio::Engine engine;
engine.init();

// Create a voice and play a 440 Hz sine
int voice = engine.createVoice();
engine.setWaveform(voice, broaudio::Waveform::Sine);
engine.setFrequency(voice, 440.0f);
engine.setGain(voice, 0.5f);
engine.startVoice(voice, engine.currentTime());

// Play a sample clip
int clip = engine.createClip(samples, numSamples);
int inst = engine.playClip(clip, 0.8f, /*loop=*/true);

// Route a voice through a reverb bus
int reverbBus = engine.createBus();
engine.setBusReverbEnabled(reverbBus, true);
engine.setBusReverbMix(reverbBus, 0.4f);
engine.setVoiceSend(voice, reverbBus, 0.5f);

// Stream a large file from disk instead of decoding it into RAM
std::string err;
int music = engine.createStreamFromFile("song.flac", &err);
if (music >= 0) engine.setPlaybackGain(music, 0.6f);

Call engine.update() from your frame loop to run non-realtime maintenance: reaping finished voices, servicing async work, and reclaiming retired RCU snapshots.

Build

cmake -B build
cmake --build build
ctest --test-dir build

Requires a C++20 compiler, CMake 3.24+, SDL3, and the header-only sibling bromath at ../bromath. To consume it from another project:

add_subdirectory(broaudio)
target_link_libraries(your_app PRIVATE broaudio)

See docs/building.md for options, optional dependencies, and coverage.

Repository layout

Path	Contents
include/broaudio/	Public headers, mirroring src/
src/	Implementation
tests/	One executable per test, registered with CTest
third_party/	Vendored dr_libs, stb_vorbis, nlohmann; libremidi as a submodule
scripts/	coverage.ps1, the Windows coverage report
docs/	Feature list, architecture, build guide

License

MIT