@mediaway/container

Sans-IO mux and demux over Mediaway's C ABI, covering all 8 mediaway-container formats. Nothing here touches files or sockets — you push packets in and poll (or pull) bytes out, and own every byte of I/O.

| Format | API | Notes | | --- | --- | --- | | MP4 | Muxer, Demuxer (default) | fragmented MP4 (fMP4); typestated via begin() | | WebM | new Muxer("webm"), new Demuxer("webm") | same Muxer/Demuxer shape as MP4 | | Ogg | OggMuxer, OggDemuxer | no track registration — push() is ready immediately | | ADTS (AAC) | AdtsMuxer, AdtsDemuxer | raw ADTS frame stream | | FLV | FlvMuxer, FlvDemuxer | tag-based, writeHeader() before any tag | | MPEG-TS | TsMuxer, TsDemuxer | PAT/PMT + access units | | MP3 | Mp3Muxer, Mp3Demuxer | fixed Layer III frame header | | WAV | WavMuxer, parseWav() | mux via finish(); demux is a one-shot function, no class |

MP4/WebM share Muxer/Demuxer; the other 6 formats have dedicated classes because their C ABI shape genuinely differs (no track registration, out-buffer-per-call mux, or a construction-time stream list — see each module's own top comment: ogg.ts/adts.ts/flv.ts/ts.ts/mp3.ts/wav.ts).

Backed by the iso-bmff/mediaway-container core crates (sans-io, unit-tested) and the native mediaway_ffi.dll (shipped by @mediaway/ffi).

Install

npm install @mediaway/container

Windows x64 (native DLL). The @mediaway/ffi dependency is installed automatically.

MP4 mux example

import { Muxer, Demuxer, type VideoTrackInfo, type AudioTrackInfo, type Packet } from "@mediaway/container";

const muxer = new Muxer();

const videoTrack: VideoTrackInfo = {
  codec: "h264",
  width: 640,
  height: 480,
  pixelFormat: "nv12",
  timeBase: { num: 1, den: 30 },
};
const audioTrack: AudioTrackInfo = {
  codec: "aac",
  sampleRate: 48_000,
  channels: 2,
  timeBase: { num: 1, den: 48_000 },
};

const v = muxer.addVideoTrack(videoTrack);
const a = muxer.addAudioTrack(audioTrack);
const chunks: Buffer[] = [muxer.begin()]; // init segment (ftyp + moov)

for (let i = 0; i < 90; i++) {
  muxer.push({
    trackIndex: v,
    data: fakeH264Packet(i),       // your encoded bytes
    pts: i,                        // ticks of the track timeBase
    duration: 1,
    key: i % 30 === 0,
  } satisfies Packet);
}
muxer.flush();                     // finalize the last fragment
chunks.push(muxer.pollBytes());    // drain everything queued
muxer.close();
// chunks -> concatenate and write to a file / stream

MP4 demux example

const demuxer = new Demuxer();
demuxer.pushBytes(buffer);          // feed chunks as they arrive
const streams = demuxer.streams();  // TrackInfo[] once moov parsed
for (;;) {
  const packet = demuxer.pollPacket(); // Packet | null
  if (!packet) break;
  // packet.trackIndex, packet.data, packet.pts, packet.duration, packet.key
}
demuxer.close();

WebM works the same way — pass "webm" to the Muxer/Demuxer constructor: new Muxer("webm") / new Demuxer("webm").

Other formats

Ogg/ADTS/FLV/MPEG-TS/MP3/WAV are exported from the same package but have their own classes and functions (see the format table above), not Muxer/Demuxer:

import { OggMuxer, OggDemuxer } from "@mediaway/container";
import { AdtsMuxer, AdtsDemuxer } from "@mediaway/container";
import { FlvMuxer, FlvDemuxer } from "@mediaway/container";
import { TsMuxer, TsDemuxer } from "@mediaway/container";
import { Mp3Muxer, Mp3Demuxer } from "@mediaway/container";
import { WavMuxer, parseWav } from "@mediaway/container";

Each has its own DX contract because the underlying C ABI shape differs (e.g. Ogg/ADTS have no track registration; FLV needs writeHeader(); WAV mux uses a terminal finish() and WAV demux is the one-shot parseWav(buffer) function, not a class) — see src/ogg.ts, src/adts.ts, src/flv.ts, src/ts.ts, src/mp3.ts, src/wav.ts for each format's full API.

API (MP4 / WebM)

| Class | Methods | Notes | | --- | --- | --- | | Muxer | addVideoTrack, addAudioTrack, begin, push, flush, pollBytes, close | sans-io: never blocks, never touches I/O | | Demuxer | pushBytes, streams, pollPacket, close | streaming — feed repeatedly |

Errors surface as MediawayError (with an ABI-level code) across every format.

License

MIT OR Apache-2.0. Part of the Mediaway project — pre-1.0, APIs may change.