Cordova Phonegap inappbrowser losing File Api functionality - ios

Question

I am developing an app using Web Audio Api. I have discovered that there is a memory leak in the way that Safari handles audio and doesn't garbage college the Audio Context correctly. For this reason I wish to load a new page. Have that page create the Audio Context, complete the operation and then close the window, so that the memory is released.
I have done the following to achieve this.
ref = window.open('record.html', '_self'); This will open the record.html page in the Cordova WebView according to https://wiki.apache.org/cordova/InAppBrowser
1 window.open('local-url.html');// loads in the
Cordova WebView
2 window.open('local-url.html', '_self');
// loads in the Cordova WebView
The record.html page loads a javascript file, that runs the operations that I wish to run. Here is the recordLoad.js file that makes some calls to native operations ( The native API is only available if loaded in the Cordova Webview and as you can see I need to access the file system, so this is the only way I can see to do it.
window.onload = createAudioContext;
ref = null;
function createAudioContext(){
console.log('createAudioContext');
window.AudioContext = window.AudioContext || window.webkitAudioContext;
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia;
window.URL = window.URL || window.webkitURL;
audioContext = new AudioContext;
getDirectory();
}
function getDirectory(){
console.log('getDirectory');
window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, getFileSystem, fail);
}
function getFileSystem(directory){
console.log('getFileSystem');
var audioPath = localStorage.getItem('audioPath');
directory.root.getFile(audioPath, null, getVocalFile, fail);
}
function getVocalFile(fileEntry){
console.log('getVocalFile');
fileEntry.file(readVocalsToBuffer, fail);
}
function readVocalsToBuffer(file){
console.log('readVocalsToBuffer');
var reader = new FileReader();
reader.onloadend = function(evt){
var x = audioContext.decodeAudioData(evt.target._result, function(buffer){
if(!buffer){
console.log('error decoding file to Audio Buffer');
return;
}
window.voiceBuffer = buffer;
buffer = null;
loadBuffers();
});
}
reader.readAsArrayBuffer(file);
}
//web
function loadBuffers(){
console.log('loadBuffers');
var srcSong = localStorage.getItem('srcSong');
try{
var bufferLoader = new BufferLoader(
audioContext,
[
"."+srcSong
],
createOffLineContext
);
bufferLoader.load()
}
catch(e){
console.log(e.message);
}
}
//
function createOffLineContext(bufferList){
console.log('createOfflineContext');
offline = new webkitOfflineAudioContext(2, window.voiceBuffer.length, 44100);
var vocalSource = offline.createBufferSource();
vocalSource.buffer = window.voiceBuffer;
vocalSource.connect(offline.destination);
var backing = offline.createBufferSource();
backing.buffer = bufferList[0];
backing.connect(offline.destination);
vocalSource.start(0);
backing.start(0);
offline.oncomplete = function(ev){
bufferList = null;
console.log('audioContext');
console.log(audioContext);
audioContext = null;
console.log(audioContext);
vocalSource.stop(0);
backing.stop(0);
vocalSource.disconnect(0);
backing.disconnect(0);
vocalSource = null;
backing = null;
window.voiceBuffer = null;
window.renderedFile = ev.renderedBuffer;
var bufferR = ev.renderedBuffer.getChannelData(0);
var bufferL = ev.renderedBuffer.getChannelData(1);
var interleaved = interleave(bufferL, bufferR);
var dataview = encodeWAV(interleaved);
window.audioBlob = new Blob([dataview], {type: 'Wav'});
saveFile();
}
offline.startRendering();
}
// This file is very long, but once it is finished mixing the two audio buffers it writes a new file to the file system. And when that operation is complete I use
function gotFileWriter(writer){
console.log('gotFileWriter');
writer.onwriteend = function(evt){
console.log('onwriteEnd');
console.log(window.audioBlob);
delete window.audioBlob;
console.log(window.audioBlob);
// checkDirectory();
var ref = window.open('index.html', '_self');
// ref.addEventListener('exit', windowClose);
}
writer.write(audioBlob);
}
I return back to the original index.html file. This solves the memory issues. However, once I try to run the same operation a second time. ie load in the record.html file, and run the recordLoad.js file I receive an error ReferenceError: Can't find variable: LocalFileSystem
It would appear that in reload index.html some, but not all of the links to the Cordova API have been lost. I can still for example use the Media Api but not the File Api. I understand that this is a bit of a hacky way, (opening and closing windows) to solve the memory leak, but I cannot find any other way of doing it. I really need some help with this. So any pointers very very welcome.