mpeg-audio

Status: early development (0.x). Not recommended for production; public APIs may change without notice. Part of the Mediaway media stack.

Sans-IO MPEG-1/2/2.5 Layer III ("MP3") elementary-stream framing: mux writes a correct 4-byte header around already-encoded frame bodies, demux is an incremental push_bytes/poll_frame reader. MPEG audio has no container-level header — frames self-describe, so this crate frames, it does not encode/decode. No I/O in the core.

Quick start

use mpeg_audio::{ChannelMode, Demuxer, FrameHeader, MpegVersion, Muxer};

let header = FrameHeader {
    version: MpegVersion::Mpeg1,
    bitrate_kbps: 128,
    sample_rate: 44_100,
    channel_mode: ChannelMode::Stereo,
};
let muxer = Muxer::new(header)?;

let mut mp3 = Vec::new();
muxer.write_frame(&encoded_body, true, &mut mp3)?; // per-call padding bit

let mut demuxer = Demuxer::new();
demuxer.push_bytes(&mp3);
while let Some(frame) = demuxer.poll_frame()? { /* one Layer III frame body */ }

Status

Status marks: ✅ first-class (tests for claimed scope) · ⚡ Zero-Copy path (no payload copy; implies ✅) · 🆗 best-effort / prototype · 🛠️ planned · ❌ attempted and genuinely blocked · 👻 not exercisable yet (no hardware / device / session available)

Area	Status	Notes
Mux (Layer III header + per-call padding)	✅	MPEG-1/2/2.5 bitrate/sample-rate tables
Demux (incremental, partial-input safe)	✅	Reads no-CRC and CRC headers; frame length cross-checked against spec values
Layer I / II	❌	Rejected with a clear `UnsupportedLayer` error, not misparsed
Mux-side CRC	🛠️	Demux already reads it; mux writes no-CRC only
ID3v1/ID3v2 tag skip, Xing/VBR headers	🛠️	Assumes frame-aligned input

Docs

docs/roadmap.md — stages, deferred items, design decisions
mediaway-container — Mediaway-typed mp3 surface over this crate
Root README — container support matrix

Contributing

Contributions are welcome — open an issue or pull request at github.com/nyxways/mediaway.

License