Clausters

Clausters is a port of SuperCollider's scsynth audio server to Rust: a real-time audio synthesis server controlled over OSC (UDP, default port 127.0.0.1:57110). A single process opens the audio device, keeps a tree of nodes (synths and groups), and receives OSC commands to create and destroy synths, set parameters, manage buses and buffers — all with sample-accurate scheduling.

It is conceptually compatible with scsynth (same node-tree model, the same /s_new, /n_set, /c_set, /b_* commands) but uses its own def formats instead of the binary .scsyndef. Its main addition over scsynth is the FaustDef — a synth definition written in Faust and JIT-compiled by the server — as an alternative to SuperCollider's UGen graphs, which Clausters also supports through its own JSON SynthDef format.

Highlights

• Hard real-time audio thread: no allocation, locks or I/O in the audio callback. Commands arrive pre-built over lock-free FIFOs; freed memory leaves through a garbage FIFO and is dropped off the audio thread. Guarded by assert_no_alloc tests.
• Two def formats, both loaded hot over OSC: a flat SynthDef JSON list of UGens (/d_recv, default synth feature), and Faust defs — Faust source or a JSON box tree — JIT-compiled with the LLVM backend (/d_faust, faust feature). The two families are independent build features: enable both or ship a single-family server.
• Sample-accurate scheduling: NTP-timetagged bundles split the audio block at the event's exact frame, plus a direct sample clock (/clock, /sched) as a drift-free client timebase.
• Offline (NRT) rendering: the same engine renders scores to WAV without an audio device, bit-identically to a live take.
• Auto-sorted groups (/g_sortMode): execution order inferred from the buses each def reads and writes — no manual /n_before bookkeeping.
• Parallel groups (/g_parallel + --workers N): independent children run on several cores, bit-identical to the sequential result.
• Control/bus mapping (/n_map, /n_mapa): any control or Faust parameter can track a control or audio bus, live, every block.
• Several transports: OSC over UDP and TCP (both on by default) and WebSocket (--ws), plus local shared memory (--shm) and an in-process C ABI for embedding, with the sample clock and control buses readable in mapped memory.
• Configuration & persistence: a shared TOML config file (user and per-project layers) behind every boot flag, and defs persisted and reloaded across runs (--data-dir).

How to read this book

• New here? Start with Getting started: build it, run the server, play a sound.
• Driving the server over OSC? See Defs, UGens & the OSC protocol and the feature chapters (timed bundles & the sample clock, auto-sorted and parallel groups).
• Embedding it in your own program? See Using Clausters as a library and Local transports & embedding.
• Working on Clausters itself? See Architecture and Contributing.

The API reference for the library crate is the rustdoc: cargo doc --open.

License

GPL-3.0-or-later (the embedded libfaust is GPLv2+).