nickjillings@1682: /**
nickjillings@1682:  * core.js
nickjillings@1682:  * 
nickjillings@1682:  * Main script to run, calls all other core functions and manages loading/store to backend.
nickjillings@1682:  * Also contains all global variables.
nickjillings@1682:  */
nickjillings@1682: 
nickjillings@1682: /* create the web audio API context and store in audioContext*/
nickjillings@1682: var audioContext;
nickjillings@1683: var projectXML;
nickjillings@1682: var audioEngineContext;
nickjillings@1682: 
nickjillings@1682: window.onload = function() {
nickjillings@1682: 	// Function called once the browser has loaded all files.
nickjillings@1682: 	// This should perform any initial commands such as structure / loading documents
nickjillings@1682: 	
nickjillings@1682: 	// Create a web audio API context
nickjillings@1682: 	// NORE: Currently this will only work with webkit browsers (Chrome/Safari)!
nickjillings@1682: 	audioContext = new webkitAudioContext;
nickjillings@1682: 	
nickjillings@1682: 	// Create the audio engine object
nickjillings@1682: 	audioEngineContext = new AudioEngine();
nickjillings@1682: }
nickjillings@1682: 
nickjillings@1682: function loadProjectSpec(url) {
nickjillings@1682: 	// Load the project document from the given URL, decode the XML and instruct audioEngine to get audio data
nickjillings@1682: 	// If url is null, request client to upload project XML document
nickjillings@1683: 	var r = new XMLHttpRequest();
nickjillings@1683: 	r.open('GET',url,true);
nickjillings@1683: 	r.onload = function() {
nickjillings@1683: 		loadProjectSpecCallback(r.response);
nickjillings@1683: 	}
nickjillings@1683: 	r.send();
nickjillings@1683: }
nickjillings@1683: 
nickjillings@1683: function loadProjectSpecCallback(response) {
nickjillings@1683: 	// Function called after asynchronous download of XML project specification
nickjillings@1683: 	var decode = $.parseXML(response);
nickjillings@1683: 	projectXML = $(decode);
nickjillings@1683: 	
nickjillings@1683: 	// Now extract the setup tag
nickjillings@1683: 	var xmlSetup = projectXML.find('setup');
nickjillings@1683: 	var interfaceType = xmlSetup[0].attributes['interface'];
nickjillings@1683: 	var interfaceJS = document.createElement('script');
nickjillings@1683: 	interfaceJS.setAttribute("type","text/javascript");
nickjillings@1683: 	if (interfaceType.value == 'APE') {
nickjillings@1683: 		interfaceJS.setAttribute("src","ape.js");
nickjillings@1683: 	}
nickjillings@1683: 	document.getElementsByTagName("head")[0].appendChild(interfaceJS);
nickjillings@1682: }
nickjillings@1682: 
nickjillings@1682: function createProjectSave(destURL) {
nickjillings@1682: 	// Save the data from interface into XML and send to destURL
nickjillings@1682: 	// If destURL is null then download XML in client
nickjillings@1682: }
nickjillings@1682: 
nickjillings@1682: function AudioEngine() {
nickjillings@1682: 	
nickjillings@1682: 	// Create two output paths, the main outputGain and fooGain.
nickjillings@1682: 	// Output gain is default to 1 and any items for playback route here
nickjillings@1682: 	// Foo gain is used for analysis to ensure paths get processed, but are not heard
nickjillings@1682: 	// because web audio will optimise and any route which does not go to the destination gets ignored.
nickjillings@1682: 	this.outputGain = audioContext.createGain();
nickjillings@1682: 	this.fooGain = audioContext.createGain();
nickjillings@1682: 	this.fooGain.gain = 0;
nickjillings@1682: 	
nickjillings@1682: 	// Connect both gains to output
nickjillings@1682: 	this.outputGain.connect(audioContext.destination);
nickjillings@1682: 	this.fooGain.connect(audioContext.destination);
nickjillings@1682: 	
nickjillings@1682: 	// Create store for new audioObjects
nickjillings@1682: 	this.audioObjects = [];
nickjillings@1682: 	
nickjillings@1682: 	this.play = function() {
nickjillings@1682: 		// Send play command to all playback buffers for synchronised start
nickjillings@1682: 		// Also start timer callbacks to detect if playback has finished
nickjillings@1682: 	}
nickjillings@1682: 	
nickjillings@1682: 	this.stop = function() {
nickjillings@1682: 		// Send stop and reset command to all playback buffers
nickjillings@1682: 	}
nickjillings@1682: 	
nickjillings@1682: 	this.newTrack = function(url) {
nickjillings@1682: 		// Pull data from given URL into new audio buffer
nickjillings@1682: 		// URLs must either be from the same source OR be setup to 'Access-Control-Allow-Origin'
nickjillings@1682: 		var request = new XMLHttpRequest();
nickjillings@1682: 		request.open('GET',url,true);
nickjillings@1682: 		request.responseType = 'arraybuffer';
nickjillings@1682: 		// Create the audioObject with ID of the new track length;
nickjillings@1682: 		audioObjectId = this.audioObjects.length
nickjillings@1682: 		this.audioObjects[audioObjectId] = new audioObject(audioObjectId);
nickjillings@1682: 		
nickjillings@1682: 		// Create callback to decode the data asynchronously
nickjillings@1682: 		request.onload = function() {
nickjillings@1682: 			audioContext.decodeAudioData(request.response, function(decodedData) {
nickjillings@1682: 				audioObj = audioEngineContext.audioObjects[audioObjectId];
nickjillings@1682: 				audioObj.buffer = decodedData;
nickjillings@1682: 				audioObj.bufferNode.buffer = audioObj.buffer;
nickjillings@1682: 				audioObj.state = 1;
nickjillings@1682: 			}, console.log("Err - Buffer not added to " + audioObjectId));
nickjillings@1682: 		}
nickjillings@1682: 		request.send();
nickjillings@1682: 	}
nickjillings@1682: 	
nickjillings@1682: }
nickjillings@1682: 
nickjillings@1682: function audioObject(id) {
nickjillings@1682: 	// The main buffer object with common control nodes to the AudioEngine
nickjillings@1682: 	
nickjillings@1682: 	this.id = id;
nickjillings@1682: 	this.state = 0; // 0 - no data, 1 - ready
nickjillings@1682: 	
nickjillings@1682: 	// Create a buffer and external gain control to allow internal patching of effects and volume leveling.
nickjillings@1682: 	this.bufferNode = audioContext.createBufferSource();
nickjillings@1682: 	this.outputGain = audioContext.createGain();
nickjillings@1682: 	
nickjillings@1682: 	// Connect buffer to the audio graph
nickjillings@1682: 	this.bufferNode.connect(this.outputGain);
nickjillings@1682: 	this.outputGain.connect(audioEngineContext.outputGain);
nickjillings@1682: 	
nickjillings@1682: 	// the audiobuffer is not designed for multi-start playback
nickjillings@1682: 	// When stopeed, the buffer node is deleted and recreated with the stored buffer.
nickjillings@1682: 	this.buffer;
nickjillings@1682: 	
nickjillings@1682: 	this.play = function(startTime) {
nickjillings@1682: 		this.bufferNode.start(startTime);
nickjillings@1682: 	}
nickjillings@1682: 	
nickjillings@1682: 	this.stop = function() {
nickjillings@1682: 		this.bufferNode.stop(0);
nickjillings@1682: 		this.bufferNode = audioContext.createBufferSource();
nickjillings@1682: 		this.bufferNode.connect(this.outputGain);
nickjillings@1682: 		this.bufferNode.buffer = this.buffer;
nickjillings@1682: 	}
nickjillings@1682: 	
nickjillings@1682: }