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audio-loader

Build Status Code Climate js-standard-style npm Greenkeeper badge license

An simple and flexible audio buffer loader for browser and node:

var load = require('audio-loader')

// load one file
load('http://example.net/audio/file.mp3').then(function (buffer) {
  console.log(buffer) // => <AudioBuffer>
})

// load a collection of files
load({ snare: 'samples/snare.wav', kick: 'samples/kick.wav' },
  { from: 'http://example.net/'} ).then(function (audio) {
  console.log(audio) // => { snare: <AudioBuffer>, kick: <AudioBuffer> }
})

Features

  • Load single audio files or collection of them (either using arrays or data objects)
  • Load base64 encoded audio strings
  • Compatible with midi.js pre-rendered soundfonts packages like midi-js-soundfonts
  • Compatible with json encoded audio like sampled

Install

Npm

npm i --save audio-loader

Yarn

yarn add audio-loader

Browser

Download the minified distribution which exports loadAudio as window global:

<script src="audio-loader.min.js"></script>
<script>
  loadAudio({ snare: 'snare.wav' }, { from: 'oramics.github.io/sampled/' }).then(..)
</script>

Usage

Load audio files

You can load individual or collection of files:

load('http://path/to/file.mp3').then(function (buffer) {
  // buffer is an AudioBuffer
  play(buffer)
})

// apply a prefix using options.from
load(['snare.mp3', 'kick.mp3'], { from: 'http://server.com/audio/' }).then(function (buffers) {
  // buffers is an array of AudioBuffers
  play(buffers[0])
})

// the options.from can be a function
function toUrl (name) { return 'http://server.com/samples' + name + '?key=secret' }
load({ snare: 'snare.mp3', kick: 'kick.mp3' }, { from: toUrl }).then(function (buffers) {
  // buffers is a hash of names to AudioBuffers
  play(buffers['snare'])
})

Recursive loading

audio-loader will detect if some of the values of an object is an audio file name and try to fetch it:

var inst = { name: 'piano', gain: 0.2, audio: 'samples/piano.mp3' }
load(inst).then(function (piano) {
  console.log(piano.name) // => 'piano' (it's not an audio file)
  console.log(piano.gain) // => 0.2 (it's not an audio file)
  console.log(piano.audio) // => <AudioBuffer> (it loaded the file)
})

Load soundfont files

If you provide a .js file, audio-loader will interpret it as a midi.js soundfont file and try to load it:

load('acoustic_grand_piano-ogg.js').then(function (buffers) {
  buffers['C2'] // => <AudioBuffer>
})

This is a repository of them: https://github.com/gleitz/midi-js-soundfonts

API

load(source, [options])

Param Type Description
source Object the object to be loaded: can be an URL string, ArrayBuffer with encoded data or an array/map of sources
options Object (Optional) the load options for that source

Possible options keys are:

  • from {Function|String}: a function or string to convert from file names to urls. If is a string it will be prefixed to the name: load('snare.mp3', { from: 'http://audio.net/samples/' }) If it's a function it receives the file name and should return the url as string.
  • only {Array} - when loading objects, if provided, only the given keys will be included in the decoded object: load('piano.json', { only: ['C2', 'D2'] })
  • context {AudioContext}: (browser only) The audio context to use. By default uses audio-context
  • decode {Function}: a function to decode audio. It receives a buffer and must return a promise to an audio buffer.
  • fetch {Function}: a function to fetch files. It receives an url and a response type (one of 'arraybuffer' or 'text') and must return a promise to the contents

Run tests and examples

To run the test, clone this repo and:

npm install
npm test

To run the browser example:

npm i -g budo
npm run browser-example

To run the node (audiojs) example:

node example/node.js

License

MIT License