XAudioServer.js

//XAudioJS realtime audio output compatibility library
//Copyright (C) 2010-2015 Grant Galitz
//Released to Public Domain
var XAudioJSscriptsHandle = document.getElementsByTagName("script");
var XAudioJSsourceHandle = XAudioJSscriptsHandle[XAudioJSscriptsHandle.length-1].src;
function XAudioServer(channels, sampleRate, minBufferSize, maxBufferSize, underRunCallback, heartbeatCallback, postheartbeatCallback, volume, failureCallback, userEventLatch) {
	XAudioJSChannelsAllocated = Math.max(channels, 1);
	this.XAudioJSSampleRate = Math.abs(sampleRate);
	XAudioJSMinBufferSize = (minBufferSize >= (XAudioJSSamplesPerCallback * XAudioJSChannelsAllocated) && minBufferSize < maxBufferSize) ? (minBufferSize & (-XAudioJSChannelsAllocated)) : (XAudioJSSamplesPerCallback * XAudioJSChannelsAllocated);
	XAudioJSMaxBufferSize = (Math.floor(maxBufferSize) > XAudioJSMinBufferSize + XAudioJSChannelsAllocated) ? (maxBufferSize & (-XAudioJSChannelsAllocated)) : (XAudioJSMinBufferSize * XAudioJSChannelsAllocated);
	this.underRunCallback = (typeof underRunCallback == "function") ? underRunCallback : function () {};
    XAudioJSCallbackAPIEventNotificationCallback = (typeof heartbeatCallback == "function") ? heartbeatCallback : null;
    XAudioJSCallbackAPIEventNotificationCallback2 = (typeof postheartbeatCallback == "function") ? postheartbeatCallback : null;
	XAudioJSVolume = (volume >= 0 && volume <= 1) ? volume : 1;
	this.failureCallback = (typeof failureCallback == "function") ? failureCallback : function () { throw(new Error("XAudioJS has encountered a fatal error.")); };
	this.userEventLatch = (typeof userEventLatch == "object") ? userEventLatch : null;
	this.initializeAudio();
}
XAudioServer.prototype.MOZWriteAudioNoCallback = function (buffer, upTo) {
    //Resample before passing to the moz audio api:
    var bufferLength  = Math.min(buffer.length, upTo);
    for (var bufferIndex = 0; bufferIndex < bufferLength;) {
        var sliceLength = Math.min(bufferLength - bufferIndex, XAudioJSMaxBufferSize);
        for (var sliceIndex = 0; sliceIndex < sliceLength; ++sliceIndex) {
            XAudioJSAudioContextSampleBuffer[sliceIndex] = buffer[bufferIndex++];
        }
        var resampleLength = XAudioJSResampleControl.resampler(sliceIndex);
        if (resampleLength > 0) {
            var resampledResult = XAudioJSResampleControl.outputBuffer;
            var resampledBuffer = XAudioJSGetArraySlice(resampledResult, resampleLength);
            this.samplesAlreadyWritten += this.audioHandleMoz.mozWriteAudio(resampledBuffer);
        }
    }
}
XAudioServer.prototype.callbackBasedWriteAudioNoCallback = function (buffer, upTo) {
	//Callback-centered audio APIs:
    var bufferLength = Math.min(buffer.length, upTo);
	for (var bufferCounter = 0; bufferCounter < bufferLength && XAudioJSAudioBufferSize < XAudioJSMaxBufferSize;) {
		XAudioJSAudioContextSampleBuffer[XAudioJSAudioBufferSize++] = buffer[bufferCounter++];
	}
}
/*Pass your samples into here!
Pack your samples as a one-dimenional array
With the channel samples packed uniformly.
examples:
    mono - [left, left, left, left]
    stereo - [left, right, left, right, left, right, left, right]
*/
XAudioServer.prototype.writeAudio = function (buffer, upTo) {
	switch (this.audioType) {
		case 0:
			this.MOZWriteAudioNoCallback(buffer, upTo);
			this.MOZExecuteCallback();
			break;
		case 2:
			this.checkFlashInit();
		case 1:
			this.callbackBasedWriteAudioNoCallback(buffer, upTo);
			this.callbackBasedExecuteCallback();
			break;
		default:
			this.failureCallback();
	}
}
/*Pass your samples into here if you don't want automatic callback calling:
Pack your samples as a one-dimenional array
With the channel samples packed uniformly.
examples:
    mono - [left, left, left, left]
    stereo - [left, right, left, right, left, right, left, right]
Useful in preventing infinite recursion issues with calling writeAudio inside your callback.
*/
XAudioServer.prototype.writeAudioNoCallback = function (buffer, upTo) {
	switch (this.audioType) {
		case 0:
			this.MOZWriteAudioNoCallback(buffer, upTo);
			break;
		case 2:
			this.checkFlashInit();
		case 1:
			this.callbackBasedWriteAudioNoCallback(buffer, upTo);
			break;
		default:
			this.failureCallback();
	}
}
//Developer can use this to see how many samples to write (example: minimum buffer allotment minus remaining samples left returned from this function to make sure maximum buffering is done...)
//If null is returned, then that means metric could not be done.
XAudioServer.prototype.remainingBuffer = function () {
	switch (this.audioType) {
		case 0:
			return Math.floor((this.samplesAlreadyWritten - this.audioHandleMoz.mozCurrentSampleOffset()) * XAudioJSResampleControl.ratioWeight / XAudioJSChannelsAllocated) * XAudioJSChannelsAllocated;
		case 2:
			this.checkFlashInit();
		case 1:
			return (Math.floor((XAudioJSResampledSamplesLeft() * XAudioJSResampleControl.ratioWeight) / XAudioJSChannelsAllocated) * XAudioJSChannelsAllocated) + XAudioJSAudioBufferSize;
		default:
			this.failureCallback();
			return null;
	}
}
XAudioServer.prototype.MOZExecuteCallback = function () {
	//mozAudio:
	var samplesRequested = XAudioJSMinBufferSize - this.remainingBuffer();
	if (samplesRequested > 0) {
        var buffer = this.underRunCallback(samplesRequested);
		this.MOZWriteAudioNoCallback(buffer, buffer.length);
	}
}
XAudioServer.prototype.callbackBasedExecuteCallback = function () {
	//WebKit /Flash Audio:
	var samplesRequested = XAudioJSMinBufferSize - this.remainingBuffer();
	if (samplesRequested > 0) {
        var buffer = this.underRunCallback(samplesRequested);
		this.callbackBasedWriteAudioNoCallback(buffer, buffer.length);
	}
}
//If you just want your callback called for any possible refill (Execution of callback is still conditional):
XAudioServer.prototype.executeCallback = function () {
	switch (this.audioType) {
		case 0:
			this.MOZExecuteCallback();
			break;
		case 2:
			this.checkFlashInit();
		case 1:
			this.callbackBasedExecuteCallback();
			break;
		default:
			this.failureCallback();
	}
}
//DO NOT CALL THIS, the lib calls this internally!
XAudioServer.prototype.initializeAudio = function () {
    try {
        this.initializeMozAudio();
    }
    catch (error) {
        try {
            this.initializeWebAudio();
        }
        catch (error) {
            try {
                this.initializeFlashAudio();
            }
            catch (error) {
                this.audioType = -1;
                this.failureCallback();
            }
        }
    }
}
XAudioServer.prototype.initializeMozAudio = function () {
    this.audioHandleMoz = new Audio();
	this.audioHandleMoz.mozSetup(XAudioJSChannelsAllocated, XAudioJSMozAudioSampleRate);
	this.audioHandleMoz.volume = XAudioJSVolume;
	this.samplesAlreadyWritten = 0;
	this.audioType = 0;
	//if (navigator.platform != "MacIntel" && navigator.platform != "MacPPC") {
		//Add some additional buffering space to workaround a moz audio api issue:
		var bufferAmount = (this.XAudioJSSampleRate * XAudioJSChannelsAllocated / 10) | 0;
		bufferAmount -= bufferAmount % XAudioJSChannelsAllocated;
		this.samplesAlreadyWritten -= bufferAmount;
	//}
    this.initializeResampler(XAudioJSMozAudioSampleRate);
}
XAudioServer.prototype.initializeWebAudio = function () {
	if (typeof AudioContext == "undefined" || typeof XAudioJSWebAudioContextHandle == "undefined") {
		throw null;
	}
	else {
		if (!this.userEventLatch) {
			this.setupWebAudio();
		}
		else {
			var parentObj = this;
			var XAudioJSWebAudioDelayedEvent = 0;
			this.userEventLatch.addEventListener("click", function () {
				if (XAudioJSWebAudioDelayedEvent == 0) {
					parentObj.setupWebAudio();
					XAudioJSWebAudioDelayedEvent |= 1;
				}
			}, false);
			this.userEventLatch.addEventListener("touchstart", function () {
				if (XAudioJSWebAudioDelayedEvent < 2) {
					parentObj.setupWebAudio();
					XAudioJSWebAudioDelayedEvent |= 2;
				}
			}, false);
			this.userEventLatch.addEventListener("touchend", function () {
				if (XAudioJSWebAudioDelayedEvent < 4) {
					parentObj.setupWebAudio();
					XAudioJSWebAudioDelayedEvent |= 4;
				}
			}, false);
			//TODO: Restructure API to not have to potentially lie to end client about
			//the samples in buffer before user driven event callback that actually starts WA.
			this.resetCallbackAPIAudioBuffer(44100);
		}
		this.audioType = 1;
	}
}
XAudioServer.prototype.setupWebAudio = function () {
	if (XAudioJSWebAudioLaunchedContext) {
		XAudioJSWebAudioContextHandle.close();
	}
    try {
        XAudioJSWebAudioContextHandle = new AudioContext();								//Create a system audio context.
    }
    catch (error) {
       XAudioJSWebAudioContextHandle = new webkitAudioContext();							//Create a system audio context.
    }
    XAudioJSWebAudioLaunchedContext = true;
    if (XAudioJSWebAudioAudioNode) {
        XAudioJSWebAudioAudioNode.disconnect();
        XAudioJSWebAudioAudioNode.onaudioprocess = null;
        XAudioJSWebAudioAudioNode = null;
    }
	XAudioJSSamplesPerCallback = Math.pow(2, 11 + Math.floor(XAudioJSWebAudioContextHandle.sampleRate / 96000));
	XAudioJSMaxBufferSize = Math.max(XAudioJSSamplesPerCallback * XAudioJSChannelsAllocated, XAudioJSMaxBufferSize);
    try {
        XAudioJSWebAudioAudioNode = XAudioJSWebAudioContextHandle.createScriptProcessor(XAudioJSSamplesPerCallback, 0, XAudioJSChannelsAllocated);	//Create the js event node.
    }
    catch (error) {
        XAudioJSWebAudioAudioNode = XAudioJSWebAudioContextHandle.createJavaScriptNode(XAudioJSSamplesPerCallback, 0, XAudioJSChannelsAllocated);	//Create the js event node.
    }
    XAudioJSWebAudioAudioNode.onaudioprocess = XAudioJSWebAudioEvent;																			//Connect the audio processing event to a handling function so we can manipulate output
    XAudioJSWebAudioAudioNode.connect(XAudioJSWebAudioContextHandle.destination);																//Send and chain the output of the audio manipulation to the system audio output.
	this.resetCallbackAPIAudioBuffer(XAudioJSWebAudioContextHandle.sampleRate);
	/*
     Firefox has a bug in its web audio implementation...
     The node may randomly stop playing on Mac OS X for no
     good reason. Keep a watchdog timer to restart the failed
     node if it glitches. Google Chrome never had this issue.
     */
    XAudioJSWebAudioWatchDogLast = (new Date()).getTime();
    if (!XAudioJSWebAudioWatchDogTimer && navigator.userAgent.indexOf('Gecko/') > -1) {
        if (XAudioJSWebAudioWatchDogTimer) {
            clearInterval(XAudioJSWebAudioWatchDogTimer);
        }
        var parentObj = this;
        XAudioJSWebAudioWatchDogTimer = setInterval(function () {
			if(typeof XAudioJSWebAudioContextHandle.state != "undefined") {
				if (XAudioJSWebAudioContextHandle.state === 'suspended') {
					XAudioJSWebAudioWatchDogLast = (new Date()).getTime();
					try {
						XAudioJSWebAudioContextHandle.resume();
					}
					catch (e) {}
				}
				else {
					var timeDiff = (new Date()).getTime() - XAudioJSWebAudioWatchDogLast;
					if (timeDiff > 500) {
						parentObj.setupWebAudio();
					}
				}
			}
        }, 500);
    }
}
XAudioServer.prototype.initializeFlashAudio = function () {
	var existingFlashload = document.getElementById("XAudioJS");
	this.flashInitialized = false;
	this.resetCallbackAPIAudioBuffer(44100);
	switch (XAudioJSChannelsAllocated) {
		case 1:
			XAudioJSFlashTransportEncoder = XAudioJSGenerateFlashMonoString;
			break;
		case 2:
			XAudioJSFlashTransportEncoder = XAudioJSGenerateFlashStereoString;
			break;
		default:
			XAudioJSFlashTransportEncoder = XAudioJSGenerateFlashSurroundString;
	}
	if (existingFlashload == null) {
		this.audioHandleFlash = null;
		var thisObj = this;
		var mainContainerNode = document.createElement("div");
		mainContainerNode.setAttribute("style", "position: fixed; bottom: 0px; right: 0px; margin: 0px; padding: 0px; border: none; width: 8px; height: 8px; overflow: hidden; z-index: -1000; ");
		var containerNode = document.createElement("div");
		containerNode.setAttribute("style", "position: static; border: none; width: 0px; height: 0px; visibility: hidden; margin: 8px; padding: 0px;");
		containerNode.setAttribute("id", "XAudioJS");
		mainContainerNode.appendChild(containerNode);
		document.getElementsByTagName("body")[0].appendChild(mainContainerNode);
		swfobject.embedSWF(
			XAudioJSsourceHandle.substring(0, XAudioJSsourceHandle.length - 9) + "JS.swf",
			"XAudioJS",
			"8",
			"8",
			"9.0.0",
			"",
			{},
			{"allowscriptaccess":"always"},
			{"style":"position: static; visibility: hidden; margin: 8px; padding: 0px; border: none"},
			function (event) {
				if (event.success) {
					thisObj.audioHandleFlash = event.ref;
					thisObj.checkFlashInit();
				}
				else {
					thisObj.failureCallback();
					thisObj.audioType = -1;
				}
			}
		);
	}
	else {
		this.audioHandleFlash = existingFlashload;
		this.checkFlashInit();
	}
	this.audioType = 2;
}
XAudioServer.prototype.changeVolume = function (newVolume) {
	if (newVolume >= 0 && newVolume <= 1) {
		XAudioJSVolume = newVolume;
		switch (this.audioType) {
			case 0:
				this.audioHandleMoz.volume = XAudioJSVolume;
			case 1:
				break;
			case 2:
				if (this.flashInitialized) {
					this.audioHandleFlash.changeVolume(XAudioJSVolume);
				}
				else {
					this.checkFlashInit();
				}
				break;
			default:
				this.failureCallback();
		}
	}
}
//Checks to see if the NPAPI Adobe Flash bridge is ready yet:
XAudioServer.prototype.checkFlashInit = function () {
	if (!this.flashInitialized) {
		try {
			if (this.audioHandleFlash && this.audioHandleFlash.initialize) {
				this.flashInitialized = true;
				this.audioHandleFlash.initialize(XAudioJSChannelsAllocated, XAudioJSVolume);
			}
		}
		catch (error) {
			this.flashInitialized = false;
		}
	}
}
//Set up the resampling:
XAudioServer.prototype.resetCallbackAPIAudioBuffer = function (APISampleRate) {
	XAudioJSAudioBufferSize = XAudioJSResampleBufferEnd = XAudioJSResampleBufferStart = 0;
    this.initializeResampler(APISampleRate);
    XAudioJSResampledBuffer = this.getFloat32(XAudioJSResampleBufferSize);
}
XAudioServer.prototype.initializeResampler = function (sampleRate) {
    XAudioJSAudioContextSampleBuffer = this.getFloat32(XAudioJSMaxBufferSize);
	XAudioJSResampleControl = new Resampler(this.XAudioJSSampleRate, sampleRate, XAudioJSChannelsAllocated, XAudioJSAudioContextSampleBuffer);
    XAudioJSResampleBufferSize = XAudioJSResampleControl.outputBuffer.length;
}
XAudioServer.prototype.getFloat32 = function (size) {
	try {
		return new Float32Array(size);
	}
	catch (error) {
		return [];
	}
}
function XAudioJSFlashAudioEvent() {		//The callback that flash calls...
    XAudioJSCallbackAPIEventNotificationCallbackCompatTimerClear();
	XAudioJSCallbackAPIEventNotification();
    XAudioJSResampleRefill();
	var outputStr = XAudioJSFlashTransportEncoder();
    XAudioJSCallbackAPIEventNotification2();
    return outputStr;
}
function XAudioJSGenerateFlashSurroundString() {	//Convert the arrays to one long string for speed.
	var XAudioJSTotalSamples = XAudioJSSamplesPerCallback << 1;
	if (XAudioJSBinaryString.length > XAudioJSTotalSamples) {
		XAudioJSBinaryString = [];
	}
	XAudioJSTotalSamples = 0;
	for (var index = 0; index < XAudioJSSamplesPerCallback && XAudioJSResampleBufferStart != XAudioJSResampleBufferEnd; ++index) {
		//Sanitize the buffer:
		XAudioJSBinaryString[XAudioJSTotalSamples++] = String.fromCharCode(((Math.min(Math.max(XAudioJSResampledBuffer[XAudioJSResampleBufferStart++] + 1, 0), 2) * 0x3FFF) | 0) + 0x3000);
		XAudioJSBinaryString[XAudioJSTotalSamples++] = String.fromCharCode(((Math.min(Math.max(XAudioJSResampledBuffer[XAudioJSResampleBufferStart++] + 1, 0), 2) * 0x3FFF) | 0) + 0x3000);
		XAudioJSResampleBufferStart += XAudioJSChannelsAllocated - 2;
		if (XAudioJSResampleBufferStart == XAudioJSResampleBufferSize) {
			XAudioJSResampleBufferStart = 0;
		}
	}
	return XAudioJSBinaryString.join("");
}
function XAudioJSGenerateFlashStereoString() {	//Convert the arrays to one long string for speed.
	var XAudioJSTotalSamples = XAudioJSSamplesPerCallback << 1;
	if (XAudioJSBinaryString.length > XAudioJSTotalSamples) {
		XAudioJSBinaryString = [];
	}
	for (var index = 0; index < XAudioJSTotalSamples && XAudioJSResampleBufferStart != XAudioJSResampleBufferEnd;) {
		//Sanitize the buffer:
		XAudioJSBinaryString[index++] = String.fromCharCode(((Math.min(Math.max(XAudioJSResampledBuffer[XAudioJSResampleBufferStart++] + 1, 0), 2) * 0x3FFF) | 0) + 0x3000);
		XAudioJSBinaryString[index++] = String.fromCharCode(((Math.min(Math.max(XAudioJSResampledBuffer[XAudioJSResampleBufferStart++] + 1, 0), 2) * 0x3FFF) | 0) + 0x3000);
		if (XAudioJSResampleBufferStart == XAudioJSResampleBufferSize) {
			XAudioJSResampleBufferStart = 0;
		}
	}
	return XAudioJSBinaryString.join("");
}
function XAudioJSGenerateFlashMonoString() {	//Convert the array to one long string for speed.
	if (XAudioJSBinaryString.length > XAudioJSSamplesPerCallback) {
		XAudioJSBinaryString = [];
	}
	for (var index = 0; index < XAudioJSSamplesPerCallback && XAudioJSResampleBufferStart != XAudioJSResampleBufferEnd;) {
		//Sanitize the buffer:
		XAudioJSBinaryString[index++] = String.fromCharCode(((Math.min(Math.max(XAudioJSResampledBuffer[XAudioJSResampleBufferStart++] + 1, 0), 2) * 0x3FFF) | 0) + 0x3000);
		if (XAudioJSResampleBufferStart == XAudioJSResampleBufferSize) {
			XAudioJSResampleBufferStart = 0;
		}
	}
	return XAudioJSBinaryString.join("");
}
//Some Required Globals:
var XAudioJSWebAudioContextHandle = null;
var XAudioJSWebAudioAudioNode = null;
var XAudioJSWebAudioWatchDogTimer = null;
var XAudioJSCallbackAPIEventNotificationCallback = null;
var XAudioJSCallbackAPIEventNotificationCallback2 = null;
var XAudioJSCallbackAPIEventNotificationCallbackCompatTimer = setInterval(XAudioJSCallbackAPIEventNotificationDual, 16);
var XAudioJSWebAudioWatchDogLast = false;
var XAudioJSWebAudioLaunchedContext = false;
var XAudioJSAudioContextSampleBuffer = [];
var XAudioJSResampledBuffer = [];
var XAudioJSMinBufferSize = 15000;
var XAudioJSMaxBufferSize = 25000;
var XAudioJSChannelsAllocated = 1;
var XAudioJSVolume = 1;
var XAudioJSResampleControl = null;
var XAudioJSAudioBufferSize = 0;
var XAudioJSResampleBufferStart = 0;
var XAudioJSResampleBufferEnd = 0;
var XAudioJSResampleBufferSize = 0;
var XAudioJSMozAudioSampleRate = 44100;
var XAudioJSSamplesPerCallback = 2048;			//Has to be between 2048 and 4096 (If over, then samples are ignored, if under then silence is added).
var XAudioJSFlashTransportEncoder = null;
var XAudioJSBinaryString = [];
function XAudioJSWebAudioEvent(event) {		//Web Audio API callback...
	if (XAudioJSWebAudioWatchDogTimer) {
		XAudioJSWebAudioWatchDogLast = (new Date()).getTime();
	}
	//Find all output channels:
	for (var bufferCount = 0, buffers = []; bufferCount < XAudioJSChannelsAllocated; ++bufferCount) {
		buffers[bufferCount] = event.outputBuffer.getChannelData(bufferCount);
	}
    XAudioJSCallbackAPIEventNotificationCallbackCompatTimerClear();
	XAudioJSCallbackAPIEventNotification();
    //Make sure we have resampled samples ready:
	XAudioJSResampleRefill();
	//Copy samples from XAudioJS to the Web Audio API:
	for (var index = 0; index < XAudioJSSamplesPerCallback && XAudioJSResampleBufferStart != XAudioJSResampleBufferEnd; ++index) {
		for (bufferCount = 0; bufferCount < XAudioJSChannelsAllocated; ++bufferCount) {
			buffers[bufferCount][index] = XAudioJSResampledBuffer[XAudioJSResampleBufferStart++] * XAudioJSVolume;
		}
		if (XAudioJSResampleBufferStart == XAudioJSResampleBufferSize) {
			XAudioJSResampleBufferStart = 0;
		}
	}
	//Pad with silence if we're underrunning:
	while (index < XAudioJSSamplesPerCallback) {
		for (bufferCount = 0; bufferCount < XAudioJSChannelsAllocated; ++bufferCount) {
			buffers[bufferCount][index] = 0;
		}
		++index;
	}
    XAudioJSCallbackAPIEventNotification2();
}
function XAudioJSResampleRefill() {
	if (XAudioJSAudioBufferSize > 0) {
		//Resample a chunk of audio:
		var resampleLength = XAudioJSResampleControl.resampler(XAudioJSAudioBufferSize);
		var resampledResult = XAudioJSResampleControl.outputBuffer;
		for (var index2 = 0; index2 < resampleLength;) {
			XAudioJSResampledBuffer[XAudioJSResampleBufferEnd++] = resampledResult[index2++];
			if (XAudioJSResampleBufferEnd == XAudioJSResampleBufferSize) {
				XAudioJSResampleBufferEnd = 0;
			}
			if (XAudioJSResampleBufferStart == XAudioJSResampleBufferEnd) {
				XAudioJSResampleBufferStart += XAudioJSChannelsAllocated;
				if (XAudioJSResampleBufferStart == XAudioJSResampleBufferSize) {
					XAudioJSResampleBufferStart = 0;
				}
			}
		}
		XAudioJSAudioBufferSize = 0;
	}
}
function XAudioJSCallbackAPIEventNotificationCallbackCompatTimerClear() {
    if (XAudioJSCallbackAPIEventNotificationCallbackCompatTimer) {
        clearInterval(XAudioJSCallbackAPIEventNotificationCallbackCompatTimer);
    }
}
function XAudioJSCallbackAPIEventNotification() {
    if (typeof XAudioJSCallbackAPIEventNotificationCallback == "function") {
        XAudioJSCallbackAPIEventNotificationCallback();
    }
}
function XAudioJSCallbackAPIEventNotification2() {
    if (typeof XAudioJSCallbackAPIEventNotificationCallback2 == "function") {
        XAudioJSCallbackAPIEventNotificationCallback2();
    }
}
function XAudioJSCallbackAPIEventNotificationDual() {
    XAudioJSCallbackAPIEventNotification();
    XAudioJSCallbackAPIEventNotification2();
}
function XAudioJSResampledSamplesLeft() {
	return ((XAudioJSResampleBufferStart <= XAudioJSResampleBufferEnd) ? 0 : XAudioJSResampleBufferSize) + XAudioJSResampleBufferEnd - XAudioJSResampleBufferStart;
}
function XAudioJSGetArraySlice(buffer, lengthOf) {
	//Typed array and normal array buffer section referencing:
	try {
		return buffer.subarray(0, lengthOf);
	}
	catch (error) {
		try {
			//Regular array pass:
			buffer.length = lengthOf;
			return buffer;
		}
		catch (error) {
			//Nightly Firefox 4 used to have the subarray function named as slice:
			return buffer.slice(0, lengthOf);
		}
	}
}