首先需要处理下
Web Audio API
在不同浏览器下的名称兼容问题，并初始化
AudioContext
实例，
var g_audio_context = null;
try {
const AudioContext = window.AudioContext || window.webkitAudioContext;
g_audio_context = new AudioContext();
} catch (e) {
alert('Web Audio API is not supported in this browser. Chrome is strongly recommended!');
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DISCLAIMED. IN NO EVENT SHALL DANIEL GUERRERO BE LIABLE FOR ANY
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* Uses the new array typed in javascript to binary base64 encode/decode
* at the moment just decodes a binary base64 encoded
* into either an ArrayBuffer (decodeArrayBuffer)
* or into an Uint8Array (decode)
* References:
* https://developer.mozilla.org/en/JavaScript_typed_arrays/ArrayBuffer
* https://developer.mozilla.org/en/JavaScript_typed_arrays/Uint8Array
var Base64Binary = {
_keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
/* will return a Uint8Array type */
decodeArrayBuffer: function(input) {
var bytes = (input.length/4) * 3;
var ab = new ArrayBuffer(bytes);
this.decode(input, ab);
return ab;
removePaddingChars: function(input){
var lkey = this._keyStr.indexOf(input.charAt(input.length - 1));
if(lkey == 64){
return input.substring(0,input.length - 1);
return input;
decode: function (input, arrayBuffer) {
//get last chars to see if are valid
input = this.removePaddingChars(input);
input = this.removePaddingChars(input);
var bytes = parseInt((input.length / 4) * 3, 10);
var uarray;
var chr1, chr2, chr3;
var enc1, enc2, enc3, enc4;
var i = 0;
var j = 0;
if (arrayBuffer)
uarray = new Uint8Array(arrayBuffer);
uarray = new Uint8Array(bytes);
input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
for (i=0; i<bytes; i+=3) {
//get the 3 octects in 4 ascii chars
enc1 = this._keyStr.indexOf(input.charAt(j++));
enc2 = this._keyStr.indexOf(input.charAt(j++));
enc3 = this._keyStr.indexOf(input.charAt(j++));
enc4 = this._keyStr.indexOf(input.charAt(j++));
chr1 = (enc1 << 2) | (enc2 >> 4);
chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
chr3 = ((enc3 & 3) << 6) | enc4;
uarray[i] = chr1;
if (enc3 != 64) uarray[i+1] = chr2;
if (enc4 != 64) uarray[i+2] = chr3;
return uarray;
// modulize
var factory = function (global) {
global.Base64Binary = Base64Binary;
(function(global, factory) {
if (typeof module === "object" && typeof module.exports === "object") {
// For CommonJS and CommonJS-like environments where a proper `window`
// is present, execute the factory and get jQuery.
// For environments that do not have a `window` with a `document`
// (such as Node.js), expose a factory as module.exports.
// This accentuates the need for the creation of a real `window`.
// e.g. var jQuery = require("jquery")(window);
// See ticket #14549 for more info.
module.exports = global.document ?
factory(global, true) :
function(w) {
return factory(w);
} else {
factory(global);
// Pass this if window is not defined yet
})(typeof window !== "undefined" ? window : this, factory);
