audio-encode

Encode raw audio samples to any format.
JS / WASM – no ffmpeg, no native bindings, works in both node and browser.
Small API, minimal size, near-native performance, stream encoding.

import encode from 'encode-audio';

const buf = await encode.wav(channelData, { sampleRate: 44100 });

Supported formats:

Format	Package	Engine
WAV	@audio/encode-wav	JS
MP3	@audio/encode-mp3	WASM
OGG Vorbis	@audio/encode-ogg	WASM
Opus	@audio/encode-opus	WASM
WebM	@audio/encode-webm	WASM (Opus)
FLAC	@audio/encode-flac	WASM
AAC	@audio/encode-aac	WebCodecs*
AIFF	@audio/encode-aiff	JS
CAF	@audio/encode-caf	JS
QOA	@audio/encode-qoa	JS

_{* AAC uses the native WebCodecs AudioEncoder — browser-only (Chromium/Safari), throws in Node.}

Whole-file encode

Specify the format as method name. Input is Float32Array[] (one per channel), a single Float32Array (mono), or an AudioBuffer.

import encode from 'encode-audio';

const wav  = await encode.wav(channelData, { sampleRate: 44100 });
const aiff = await encode.aiff(channelData, { sampleRate: 44100 });
const caf  = await encode.caf(channelData, { sampleRate: 44100 });
const mp3  = await encode.mp3(channelData, { sampleRate: 44100, bitrate: 128 });
const ogg  = await encode.ogg(channelData, { sampleRate: 44100, quality: 5 });
const flac = await encode.flac(channelData, { sampleRate: 44100 });
const opus = await encode.opus(channelData, { sampleRate: 48000, bitrate: 96 });
const webm = await encode.webm(channelData, { sampleRate: 48000, bitrate: 96 });
const qoa  = await encode.qoa(channelData, { sampleRate: 44100 });
const aac  = await encode.aac(channelData, { sampleRate: 44100, bitrate: 128 }); // browser only

encode.formats lists the supported names and encode.mime maps each to a MIME type — handy for format-agnostic pipelines.

Chunked encoding

Call with just options (no data) to create a streaming encoder:

import encode from 'encode-audio';

const enc = await encode.mp3({ sampleRate: 44100, bitrate: 128 });

const a = await enc(chunk1);  // Uint8Array
const b = await enc(chunk2);
const c = await enc(null);        // end of stream — flush + free

// explicit control: enc.flush(), enc.free()

Streaming

Pass an async iterable as data — returns an async generator:

import encode from 'encode-audio'

for await (let buf of encode.mp3(audioSource, { sampleRate: 44100, bitrate: 128 })) {
  // buf is Uint8Array
}

Works with any async iterable source.

Options

Option	Description	Applies to
sampleRate	Output sample rate (required)	all
bitrate	Target bitrate in kbps	mp3, opus, webm, aac
quality	Quality 0–10 (VBR)	ogg, mp3
channels	Output channel count	all
bitDepth	Bit depth: 16/24/32 (wav), 16/24 (aiff, flac), 16/32 (caf)	wav, aiff, flac, caf
compression	FLAC compression level 0–8	flac
application	'audio', 'voip', or 'lowdelay'	opus, webm
meta	Tags (see below)	wav, mp3, flac, aiff, ogg, opus

Metadata

Pass meta (and, for wav, markers/regions) straight to the encoder:

let bytes = await encode.flac(channelData, {
  sampleRate: 44100,
  meta: { title: 'Hare Krishna', artist: 'Prabhupada', year: '1966' }
})

Tags work for wav, mp3, flac, aiff, ogg and opus. Cue markers and regions are wav-only. opus bakes tags into the OpusTags header at encode time (stays fully streaming); the others splice tags into the finished file — so passing meta to a streaming/chunked encode of wav/mp3/flac/aiff/ogg buffers the output and emits it on flush.

You can also tag already-encoded bytes via encode-audio/meta:

import { wav } from 'encode-audio/meta'

let out = wav(bytes, {
  meta: { title: 'Hare Krishna', artist: 'Prabhupada', year: '1966' },
  markers: [{ sample: 44100, label: 'verse' }],
  regions: [{ sample: 88200, length: 44100, label: 'chorus' }]
})

Each codec sub-package also exposes its writer directly:

import { writeMeta } from '@audio/encode-mp3/meta'
let tagged = writeMeta(mp3Bytes, { meta: { title: 'foo' } })

See also

• audio-decode – decode any audio format to raw samples.
• wasm-media-encoders – compact WASM MP3 & Vorbis encoders.
• AudioEncoder – native WebCodecs encoder API.

License

MIT

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