Pure JS implementation of the Web Audio API
npm install @descript/web-audio-js!Node CI
> Pure JS implementation of the Web Audio API
Fork of mohayonao/web-audio-engine with following changes:
- Use TypeScript and fix some types (#5)
- Remove BaseAudioContext.suspend() (#6)
- Add new RawDataAudioContext (#5)
- Add support for DynamicsCompressorNode (#1)
- Bug fixes
- Fixes for BiquadFilterNode and DelayNode (#8)
- Fix WAVE file decoding (#5)
- Fix AudioNode.disconnect(x) not disconnecting (#7)
``
npm install --save web-audio-engine
web-audio-engine provides some AudioContext class for each use-case: audio playback, rendering and simulation.
StreamAudioContext writes raw PCM audio data to a writable node stream. It can be used to playback audio in realtime.
##### new StreamAudioContext(opts?: object)
Creates new StreamAudioContext instance.
- opts.sampleRate: number audio sample rate (in Hz) - _default: 44100_opts.numberOfChannels: number
- audio channels (e.g. 2: stereo) - _default: 2_opts.blockSize: number
- samples each rendering quantum - _default: 128_opts.bitDepth: number
- bits per sample - _default: 16_opts.float: boolean
- use floating-point values - _default: false_
##### context.pipe(destination: stream.Writable): stream.Writable
:constructionworker: \_TODO: WRITE DESCRIPTION
`js
import { StreamAudioContext as AudioContext } from 'web-audio-engine';
const context = new AudioContext();
// Set the output for audio streaming
context.pipe(process.stdout);
// If you want to playback sound directly in this process, you can use 'node-speaker'.
// const Speaker = require("speaker");
// context.pipe(new Speaker());
// Start to render audio
context.resume();
// composeWith(context);
`
RenderingAudioContext records audio data with stepwise processing. It is used to export to a wav file or test a web audio application.
##### new RenderingAudioContext(opts?: object)
Creates new RenderingAudioContext instance.
- opts.sampleRate: number audio sample rate (in Hz) - _default: 44100_opts.numberOfChannels: number
- audio channels (e.g. 2: stereo) - _default: 2_opts.blockSize: number
- samples each rendering quantum - _default: 128_
##### context.processTo(time: number|string)
Executes rendering process until the provided time.
- time: e.g. 10 (10 seconds), "01:30.500" (convert to 90.5 seconds)
##### context.exportAsAudioData(): AudioData
Exports the rendered data as AudioData format.
##### context.encodeAudioData(audioData: AudioData, opts?:object): Promise< ArrayBuffer >
Encode audio data to the binary format.
- audioData: AudioData
- bits per sample - _default: 16_opts.float: boolean
- use floating-point values - _default: false_
`js
import fs from 'fs';
import { RenderingAudioContext as AudioContext } from 'web-audio-engine';
const context = new AudioContext();
// composeWith(context);
context.processTo('00:01:30.000');
// context.currentTime -> 90.00054421768708
context.processTo('00:02:00.000');
// context.currentTime -> 120.00072562358277
const audioData = context.exportAsAudioData();
context.encodeAudioData(audioData).then((arrayBuffer) => {
fs.writeFile('output.wav', new Buffer(arrayBuffer));
});
`
RawDataAudioContext allows you to synchronously step through an AudioContext. This is useful for streaming output at
and controlling the rate
##### new RawDataAudioContext(opts?: object)
Creates new RenderingAudioContext instance.
- opts.sampleRate: number audio sample rate (in Hz) - _default: 44100_opts.numberOfChannels: number
- audio channels (e.g. 2: stereo) - _default: 2_opts.blockSize: number
- samples each rendering quantum - _default: 128_
##### context.process(channelData: Float32Array[], offset: number = 0)
Renders the next blockSize samples of audio into channelData.
`js
import { RawDataAudioContext } from 'web-audio-engine';
const context = new RawDataAudioContext();
const { blockSize } = context;
const channelData = [
new Float32Array(blockSize),
new Float32Array(blockSize),
];
for (let i = 0; i < 100_000; i += blockSize)
context.process(channelData);
// Do something with channeLData
}
`
:constructionworker: \_TODO: WRITE DESCRIPTION
##### new WebAudioContext(opts?: object)
Creates new WebAudioContext instance.
- opts.context?: AudioContext the native Web Audio API AudioContext instanceopts.destination?: AudioNode
- - _default: opts.context.destination_opts.numberOfChannels: number
- audio channels (e.g. 2: stereo) - _default: 2_opts.blockSize: number
- samples each rendering quantum - _default: 128_
`html`
This context is compatible with the natvie Web Audio API OfflineAudioContext.
`js
import { OfflineAudioContext } from 'web-audio-engine';
const context = new OfflineAudioContext(2, 44100 * 10, 44100);
// composeWith(context);
context.startRendering().then((audioBuffer) => {
console.log(audioBuffer);
});
`
`
interface AudioData {
numberOfChannels?: number;
length?: number;
sampleRate: number;
channelData: Float32Array[];
}
The default decoder of web-audio-engine supports "wav" format only. If you need to support other audio format, you are necessary to prepare a decoder yourself.
##### decoder.get(type: string): function
Returns the function for decoding currently set.
##### decoder.set(type: string, decodeFn: function)
Sets the function for decoding.
- decodeFn: (audioData: ArrayBuffer, opts?: object) => Promise< AudioData > The decoding to use.
##### decoder.decode(audioData: ArrayBuffer, opts?: object): Promise< AudioData >
Executes decoding.
- audioData: ArrayBuffer
###### mp3 decoder example
`js
import wae from 'web-audio-engine';
import mp3decoder from '/path/to/mp3decoder';
import fs from 'fs';
wae.decoder.set('mp3', mp3decoder);
const AudioContext = wae.RenderingAudioContext;
const context = new AudioContext();
const audioData = fs.readFileSync('amen.mp3');
context.decodeAudioData(audioData).then((audioBuffer) => {
console.log(audioBuffer);
});
`
The default encoder of web-audio-engine supports "wav" format only. If you need to support other audio format, you are necessary to prepare an encoder yourself.
##### encoder.get(type: string): function
Returns the function for encoding currently set.
##### encoder.set(type: string, encodeFn: function)
Sets the function for encoding.
- encodeFn: (audioData: AudioData, opts?: object) => Promise< ArrayBuffer > The encoding to use.
##### encoder.encode(audioData: AudioData, opts?: object): Promise< ArrayBuffer >
Executes encoding.
- audioData: AudioData
- audio format type - _default: "wav"_
###### mp3 encoder example
`js
import wae from 'web-audio-engine';
import mp3encoder from '/path/to/mp3encoder';
import fs from 'fs';
wae.encoder.set('mp3', mp3encoder);
const AudioContext = wae.RenderingAudioContext;
const context = new AudioContext();
const audioData = context.exportAsAudioData();
context.encodeAudioData(audioData, { type: 'mp3' }).then((arrayBuffer) => {
fs.writeFile('output.mp3', new Buffer(arrayBuffer));
});
`
- AnalyserNode
-
-
-
-
-
-
- (audio rate parameter is not supported)ChannelMergerNode
-
-
- (noisy..)DynamicsCompressorNode
-
-
-
- (use wave-table synthesis, not use periodic wave)PeriodicWave
-
-
-
-
- The other not implemented nodes will pass its input to its output without modification.
- See: Comparison Chart of implemented nodes
`js
import Speaker from 'speaker';
import { StreamAudioContext as AudioContext } from 'web-audio-engine';
const context = new AudioContext();
const osc = context.createOscillator();
const amp = context.createGain();
osc.type = 'square';
osc.frequency.setValueAtTime(987.7666, 0);
osc.frequency.setValueAtTime(1318.5102, 0.075);
osc.start(0);
osc.stop(2);
osc.connect(amp);
osc.onended = () => {
context.close().then(() => {
process.exit(0);
});
};
amp.gain.setValueAtTime(0.25, 0);
amp.gain.setValueAtTime(0.25, 0.075);
amp.gain.linearRampToValueAtTime(0, 2);
amp.connect(context.destination);
context.pipe(new Speaker());
context.resume();
`
The online demo is here. In this site, you can compare web-audio-engine and the native Web Audio API.
- https://mohayonao.github.io/web-audio-engine/demo/
`
$ git clone git@github.com:mohayonao/web-audio-engine.git
$ cd web-audio-engine
$ npm install && npm run build
$ cd demo
$ npm install
$ node demo --help
Simplest play demo with node-speaker.
`
$ node demo sines
Rendering and export to the wav file.
`
$ node demo -o out.wav sines
Currently, this benchmark doesn't work in Chrome or Safari, please use Firefox.
- https://mohayonao.github.io/web-audio-engine/benchmark/
`
$ git clone git@github.com:mohayonao/web-audio-engine.git
$ cd web-audio-engine
$ npm install && npm run build
$ cd benchmark
$ npm install
$ node .
MIT