allen

Utilities for the Web Audio API

npm install allen
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allen

Build Status

allen is a collection of utilities for the Web Audio API. As of right now, mostly type checking different objects to determine what kind of type of node an object is, but if you find yourself reusing the same methods when developing with the Web Audio API, please add them!

Installation

Install via npm, bower or component(1)

npm install allen
component install jsantell/allen

Methods

getAudioContext()

Creates and returns an available AudioContext for the environment. If this method was called previously, or an AudioContext was set via setAudioContext(), then the same instance will be returned.

setAudioContext( context )

Sets the AudioContext to be returned from getAudioContext().

isAudioContext( node )

Returns true if node is an AudioContext; false otherwise.

isAudioSource( node )

Returns true if node inherits from an AudioSourceNode, like BufferSourceNode, MediaElementAudioSourceNode, MediaStreamAudioSourceNode or OscillatorNode; false otherwise.

isAudioDestination( node )

Returns true if node is an AudioDestinationNode; false otherwise.

isAudioNode( node )

Returns true if node inherits from AudioNode; false otherwise.

isRegularAudioNode( node )

Returns true if node inherits from AudioNode, and is not a source or destination node; false otherwise.

isAudioParam( param )

Returns true if param inherits from AudioParam; false otherwise.

getBuffer( url, callback, [sendImmediately] )

Sets up an XHR GET to the url, sets responseType to 'arraybuffer', and calls callback on load. If sendImmediately truthy, calls send() on the xhr object. Returns the xhr object. Used commonly with the Web Audio API.

canPlayType( type )

Checks if the browser can play audio of type. Strings accepted: 'ogg', 'mp3', 'wav', 'm4a'

Example

  var
    ctx = allen.getAudioContext(),
    src = ctx.createMediaElementSource( new Audio() ),
    gain = ctx.createGainNode();

  allen.isAudioNode( gain );  // true
  allen.isAudioNode( src );   // true
  allen.isAudioSource( src ); // true
  allen.isAudioSource( gain ); // false
  allen.isAudioParam( gain.gain ); // true

Development

Init and update git submodules and install grunt installed globally -- build src and specs and run tests with grunt, or fire off the watcher with grunt watch to build and test changes.

Run tests with grunt mocha. In test/mocks/mockContext.coffee, there is a mock AudioContext object for running tests headlessly -- tests should pass in PhantomJS, as well as browsers.

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