README.md
# Audio [](https://github.com/audiojs/audio/actions/workflows/test.yml)
Data structure for audio manipulations.
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- gallery:
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## Usage
[](https://npmjs.org/package/audio/)
```js
const Audio = require('audio')
```
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## Use-cases
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ideas:
- image
file → waveform → processed waveform → file
- try yourself - requirebin demo with file opener and processing
mvp:
- stats: averages, variance
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- delete data (splice?)
- insert data (splice?)
- remove Buffer, process from exports
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### Load `./sample.mp3`, trim, normalize, fade in, fade out, save:
```js
let audio = await new Audio('./sample.mp3')
audio
.trim() // remove silent head/tail
.normalize() // make sure max amplitude is at 1
.fade(.5) // fade in 0.5s at the beginning
.fade(-3) // fade out 3s at the end
.save('sample-edited.wav') // save as file
```
### Record 4s of mic input.
```js
navigator.getUserMedia({audio: true}, stream =>
let audio = await new Audio(stream)
audio.save('my-record.wav')
)
```
### Record and download 2 seconds of web-audio experiment
```js
//create web-audio experiment
let ctx = new AudioContext()
let osc = ctx.createOscillator()
osc.type = 'sawtooth'
osc.frequency.value = 440
osc.start()
osc.connect(ctx.destination)
//record 2 seconds of web-audio experiment
let audio = await Audio.record(osc, 2)
audio.save('experiment.wav')
osc.stop()
```
### Download AudioBuffer returned from offline context
```js
//setup offline context
let offlineCtx = new OfflineAudioContext(2, 44100*40, 44100)
audioNode.connect(offlineCtx)
//process result of offline context
offlineCtx.startRendering().then((audioBuffer) => {
Audio(audioBuffer).save()
})
```
### Montage audio
```js
let audio = await Audio('./record.mp3')
// repeat slowed down fragment
audio.write(audio.slice(2.1, 1).scale(.9), 3.1)
// delete fragment, fade out starting from 0.3s for the duration of 2.1s
audio.remove(2.4, 2.6).fade(.3, 2.1)
// insert other fragment not overwriting the existing data
audio.insert(await Audio('./other-record.mp3'))
audio.save('edited-record', 'wav')
```
### Render waveform of HTML5 `<audio>`
```js
import Waveform from '@a-vis/waveform'
//create waveform renderer
let waveform = Waveform();
//get audio element
let audio = <audio src="./chopin.mp3"/>
//create audio holder
audio.on('load', (err, audio) => {
let buf = audio.read(4096).getChannelData(0)
//put left channel data to waveform renderer
waveform.push(data).render()
})
```
### Process audio with _audio-*_ modules
```js
const Biquad = require('audio-biquad')
let lpf = new Biquad({frequency: 2000, type: 'lowpass'})
let audio = Audio(10).noise().process(lpf)
```
Data handle - subaudio, for sprites etc
Load intro, append 1s pause, start recording. Once ended, save as file.
Audio(['./intro.mp3', 1, MediaStream]).once('ready', (err, audio) => audio.save(Date() + '-recording.mp3'))
## [API](https://github.com/audiojs/audio/blob/master/api.md)
**1. [Core](#creation)**
* [new Audio(src?, opts?)]()
* [Audio.from(a, b?, c?, ..., opts?)]()
* [Audio.load(url, opts?, cb?)]()
* [Audio.decode(buf, opts?, cb?)]()
* [audio.buffer]()
* [audio.channels]()
* [audio.duration]()
* [audio.length]()
* [audio.sampleRate]()
* [audio.time(offset)]()
* [audio.offset(time)]()
* [Audio.gain(db)]()
* [Audio.db(gain)]()
* [Audio.isAudio(a)]()
* [Audio.isEqual(a, b, ...c)]()
* [audio.serialize(format)]()
* [audio.save(filename, opts?)]()
* [Audio.record(stream, opts?)]()
* [audio.stream(dst, opts?, onend?)]()
* [audio.clone()]()
**2. [Manipulations](#manipulations)**
* [audio.read(dst?, t?, dur?, opts?)]()
* [audio.write(src|val, t?, dur?, opts?)]()
* [audio.insert(data, t?, dur?, opts?)]()
* [audio.slice(t?, dur?, opts?)]()
* [audio.remove(t?, dur?, opts?)]()
* [audio.pad(dur, opts?)]()
* [audio.shift(amt, t?, opts?)]()
* [audio.trim(opts?)]()
* [audio.repeat(times, t?, dur?, opts?)]()
* [audio.reverse(t?, dur?, opts?)]()
* [audio.invert(t?, dur?, opts?)]()
* [audio.gain(db, t?, dur?, opts?)]()
* [audio.fade(t?, dur, opts?)]()
* [audio.normalize(t?, dur?, opts?)]()
* [audio.pan(amt, t?, dur?, opts?)]()
* [audio.mix(audio, t?, dur?, opts?)]()
* [audio.scale(amt, t?, opts?)]()
* [audio.map(fn, opts?)]()
**3. [Metrics](#metrics)**
* [audio.statistics(t?, dur?, opts?)]()
* [audio.bounds(t?, dur?, opts?)]()
* [audio.spectrum(t?, dur, opts?)]()
* [audio.cepstrum(t?, dur)]()
* [audio.loudness(t?, dur)]()
* [audio.memory(t?, dur, opts?)]()
**4. [Playback](#playback)**
* [audio.play(t?, dur?, opts?)]()
* [audio.pause()]()
* [audio.muted]()
* [audio.loop]()
* [audio.rate]()
* [audio.volume]()
* [audio.paused]() <kbd>readonly</kbd>
* [audio.currentTime]()
## See Also
* [audiojs](https://github.com/audiojs) − open-source audio components for javascript
* [web-audio-api](https://github.com/audiojs/web-audio-api) − web-audio-api implementation for nodejs
## Related
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## Alternatives
* [wad](https://github.com/rserota/wad)
* [tuna](https://github.com/Theodeus/tuna)
* [aural](https://github.com/mjanssen/aural)
* [pizzicato](https://github.com/alemangui/pizzicato)
* [ciseaux](https://github.com/mohayonao/ciseaux)
* [pjsaudio](https://github.com/corbanbrook/pjsaudio)
* [howler](https://github.com/goldfire/howler.js)
* [dsp.js](https://github.com/corbanbrook/dsp.js)
* [audiolet](https://github.com/oampo/Audiolet)
* [dynamicaudio](https://github.com/bfirsh/dynamicaudio.js)
* [audiolib](https://github.com/jussi-kalliokoski/audiolib.js)
* [bufaudio](https://github.com/eipark/buffaudio)
* [crunker](https://github.com/jackedgson/crunker)
* [sonorous](https://github.com/EkoLabs/sonorous)
* [waud](https://github.com/waud/waud)
* [tape.js](https://github.com/alien35/tape.js)
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## Credits
Acknowledgement to contributors:
* [Dmitry Yv](https://github.com/dy) for redesign and take on main implementation.
* [Jamen Marz](https://github.com/jamen) for initiative and help with making decisions.
* [Daniel Gómez Blasco](https://github.com/danigb/) for patience and work on [audio-loader](https://github.com/audiojs/audio-loader).
* [Michael Williams](https://github.com/ahdinosaur) for audio stream insights.
-->
## License
[MIT](LICENSE) © <a href="https://github.com/audiojs">audiojs</a>.