maolan-engine

maolan-engine is the Rust audio engine that powers Maolan.

It provides:

• Real-time Audio and MIDI track processing
• Timeline-oriented recording and clip playback
• Track routing and plugin graph routing
• Offline bounce and export helpers
• Out-of-process (OOP) plugin hosting for CLAP, VST3, and LV2 (Unix) — each plugin runs in a separate OS process for crash isolation
• Platform audio backends for Linux, FreeBSD, macOS (CoreAudio), and Windows (WASAPI)

Architecture

The engine uses a two-tier process model:

1. Main DAW process — hosts the UI, audio engine, and project state.
2. Plugin host processes — one per plugin instance, launched by the engine. Each host loads the plugin binary in-process and communicates with the DAW via shared-memory IPC (mmap on Unix, CreateFileMappingW on Windows) and lightweight cross-process events (pipe on Unix, named auto-reset events on Windows).

Plugins are never loaded directly into the DAW. If a plugin crashes, only its host process dies; the DAW detects the failure, bypasses the plugin, and continues playback.

Cargo features

All capabilities beyond core real-time track processing are opt-in cargo features; the crate builds with default = []:

Feature	Enables	Dependencies
audio	Audio file decode/encode (import, export, recording takes, freeze/bounce WAV)	symphonia, oxideav-*
midi	Standard MIDI File import/export (.mid clips and MIDI takes)	midly
plugins	Out-of-process CLAP/VST3/LV2/AU plugin hosting, plugin graphs, plugin messages	maolan-plugin-protocol
mixosc	OSC control-surface automation	mixosc

Without audio, engine-rate PCM/WAV clips still play via the codec-free seekable streaming path, but compressed formats and file export are unavailable. Without midi, MIDI tracks still process internal events, but .mid file I/O is disabled. Without plugins, the plugin API is absent entirely.

Platform support

Feature	Linux	FreeBSD	macOS	Windows
Audio backend	ALSA, JACK	OSS, JACK	CoreAudio	WASAPI
CLAP hosting	✅ OOP	✅ OOP	✅ OOP	✅ OOP
VST3 hosting	✅ OOP	✅ OOP	✅ OOP	✅ OOP
LV2 hosting	✅ OOP	✅ OOP	✅ OOP	N/A
GUI embedding	X11	—	—	HWND (SetParent)