Crate rusty_opus 

A complete, pure-Rust implementation of the Opus audio codec (RFC 6716 / RFC 8251): encoder and decoder, SILK, CELT and Hybrid modes, with no C code and no dependencies.

Quick start

use rusty_opus::{Application, Error, OpusDecoder, OpusEncoder};

const RATE: i32 = 48_000;
const FRAME: usize = 960; // 20 ms at 48 kHz

let mut encoder = OpusEncoder::new(RATE, 2, Application::Audio)?;
encoder.bitrate_bps = 96_000;
let pcm = vec![0.0f32; FRAME * 2]; // interleaved stereo, nominal range [-1, 1]
let mut packet = [0u8; 1500];
let len = encoder.encode(&pcm, FRAME, &mut packet)?;

let mut decoder = OpusDecoder::new(RATE, 2)?;
let mut out = vec![0.0f32; FRAME * 2];
assert_eq!(decoder.decode(&packet[..len], FRAME, &mut out)?, FRAME);

// An empty packet signals a lost frame: the decoder conceals it.
assert_eq!(decoder.decode(&[], FRAME, &mut out)?, FRAME);

// Malformed input is an error, never a panic.
assert!(decoder.decode(&[0xFF, 0x03], FRAME, &mut out).is_err());

Public API

• OpusEncoder and OpusDecoder — mono/stereo coding, packet-loss concealment (OpusDecoder::decode with an empty packet) and in-band FEC (OpusDecoder::decode_fec).
• multistream — surround encoding and decoding (mapping families 0 and 1).
• repacketizer — merge, split, pad and unpad packets without re-encoding.
• parallel — frame-parallel and batch encoding across threads.
• Error — the error type of every fallible operation; variants mirror libopus error codes.

Other modules are internal codec stages: they are public so integration tests can reach them, but hidden from this documentation and not covered by semantic versioning.

Performance and platforms

SIMD kernels (AVX2/FMA, AVX and SSE2 on x86; NEON on aarch64) are selected at runtime, each with a scalar fallback; RUSTY_OPUS_ISA=scalar|sse2|avx|avx2 caps the instruction set. After warm-up, OpusEncoder::encode and OpusDecoder::decode perform no heap allocation per frame. The crate builds for every Rust target, including wasm32.

Modules

multistream

Opus multistream (surround) — port of the core of src/opus_multistream_{encoder,decoder}.c. Wraps N mono/coupled Opus coders behind a channel-mapping layout so >2-channel audio (quad, 5.1, 7.1) can be coded as a set of standard Opus streams concatenated with the self-delimited framing.

parallel

Frame/chunk-parallel Opus encoding (R1) — the structural win that beats a single-threaded libopus on wall-clock.

repacketizer

Port of libopus src/repacketizer.c + the packet helpers from src/opus.c: split Opus packets into frames and recombine/re-frame/pad them WITHOUT re-encoding. Used to merge several packets into a longer one, split a multi-frame packet, or pad a packet to a target size (e.g. for CBR transport). All frames in a repacketizer must share the same TOC config (mode/bandwidth/frame-size); only the code (0..3) and framing change.

Macros

tell_frac_inline

Structs

OpusDecoder

An Opus decoder for one mono or stereo stream.

OpusEncoder

An Opus encoder for one mono or stereo stream.

Enums

Application

The intended use of an encoder, which steers its mode and tuning decisions (libopus OPUS_APPLICATION_*; the discriminants are the libopus values).

Bandwidth

Audio bandwidth of a coded stream (libopus OPUS_BANDWIDTH_*; the discriminants are the libopus values).

Error

Why an encoder, decoder, or packet operation failed.

SignalType

OPUS_SET_SIGNAL hint: bias mode selection toward speech or music. None = OPUS_AUTO (let the analysis decide).