@dr.pogodin/audio-loader

Audio Loader

It used to be a patched fork of audio-loader library, but starting from v1.2.0 it has been refactored to drop NodeJS support, and thanks to that to use the minimum of dependencies (many of which were not actively maintained).

There are also some changes in the API.

ORIGINAL README BELOW, IT IS PENDING AN UPDATE

An simple and flexible audio buffer loader for browser.

var load = require('@dr.pogodin/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 – Optional. 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} - Optional. When loading objects, if provided, only the given keys will be included in the decoded object: load('piano.json', { only: ['C2', 'D2'] })`
• 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

License

MIT License