WEB SOUNDER オーディオデータを再生する

WEB SOUNDER オーディオデータを再生する

// 参考
// [WEB SOUNDER オーディオデータを再生する](http://curtaincall.weblike.jp/portfolio-web-sounder/webaudioapi-basic/audio)  

window.onload = function () {
	// body...
	alert('test_02.js: window.onloadが呼ばれました.');
}

window.AudioContext = window.AudioContext || window.webkitAudioContext;
//Create the instance of AudioContext
var context = new AudioContext();
var xhr = new XMLHttpRequest();
var url = './media/sample.wav';

//XMLHttpRequest Level 2
xhr.responseType = 'arraybuffer';
// xhrの状態変化時に呼び出される
// http://memopad.bitter.jp/w3c/ajax/ajax_xmlhttprequest_onreadystatechange.html
xhr.onreadystatechange = function(){
    if ((xhr.readyState === xhr.DONE) && (xhr.status === 200)) {
        var arrayBuffer = xhr.response;
        if (arrayBuffer instanceof ArrayBuffer) {
        	
	var successCallback = function(audioBuffer){
	    /* audioBuffer is the instance of AudioBuffer */

	    //Create the instance of AudioBufferSourceNode
	    var source = context.createBufferSource();

	    //Set the instance of AudioBuffer
	    source.buffer = audioBuffer;

	    //Set parameters
	    source.loop               = false;
	    source.loopStart          = 0;
	    source.loopEnd            = audioBuffer.duration;
	    source.playbackRate.value = 1.0;

	    //AudioBufferSourceNode (input) -> AudioDestinationNode (output)
	    source.connect(context.destination);

	    //for legacy browsers
	    source.start = source.start || source.noteOn;
	    source.stop  = source.stop  || source.noteOff;

	    //Start audio
	    source.start(0);

	    var endedCallback = function(event){
	        //Stop audio
	        source.stop(0);

	        event ? window.alert('STOP by "on' + event.type + '" event handler !!') : window.alert('STOP by "setTimeout" method !!');

	        //Audio is not started !!
	        //It is necessary to create the instance of AudioBufferSourceNode again

	        //source.start(0);
	    };

	    //The 'onended' event is implemented ?
	    if ('onended' in source) {
	        source.onended = endedCallback;
	    } else if (!source.loop) {
	        window.setTimeout(endedCallback, ((source.buffer.duration / source.playbackRate.value) * 1000));
	    }
	};

           var errorCallback = function(){
                window.alert('Error : "decodeAudioData" method !!');
            };

            //Create the instance of AudioBuffer (Asynchronously)
            context.decodeAudioData(arrayBuffer, successCallback, errorCallback);
        }
    }
};
xhr.open('GET', url, true);
xhr.send(null);