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audio.js

This module provides the interface to the Web Audio API. It handles the playback of the audio clips that are processed by the filters we design.

 
             		           
                               
                            
                                
                            		                            
define(
    [],
    function() {

    var audio = {

        processor: null,
        source: null,
        context: null,
        buffers: [],



             		           
                               
                            
                                
               
Attempts to initialize the audio context, and creates a script processor node 
which will be responsible for the actual signal processing. The processs callback
is the method which runs the currently active filter over the queued audio buffer.
             		                            
        init: function(process) {
            if (webkitAudioContext) {
                this.context = new webkitAudioContext();
                this.processor = this.context.createScriptProcessor(2048);
                this.processor.onaudioprocess = process;
                this.processor.connect(this.context.destination);
                $('#web-audio-enabled').show();
            }
        },



             		           
                               
                            
                                
               
Asynchronously loads an audio file with URI given by file and stores it in the 
dictionary of audio buffers. success is an optional callback function to run 
when the loading was successful.
             		                            
        loadAudio: function(file, success) {
            var self = this;
            var request = new XMLHttpRequest();
            request.open('GET', file, true);
            request.responseType = 'arraybuffer';
            request.onload = function() {
                self.context.decodeAudioData(request.response,
                    function(buffer) {
                        self.buffers[file] = buffer;
                        if (success) success();
                    }
                );
            };
            request.send();
        },



             		           
                               
                            
                                
               
Stops the current playback, and starts the playback of the audio file with URI given by 
file, hooking it up to the script processor that runs the currently active filter. 
There is no playback if the audio clip could not be found in the audio buffer dictionary.
             		                            
        playAudio: function(file) {
            if (this.source) this.source.stop(0);
            if (!this.buffers[file]) return;
            this.source = this.context.createBufferSource();
            this.source.buffer = this.buffers[file];
            this.source.connect(this.processor);
            this.source.start(0);
        },



             		           
                               
                            
                                
               
Stops the current playback.
             		                            
        stopAudio: function() {
            if (this.source) this.source.stop(0);
        }
    };

    return audio;
});