audio buffer loop

var SpectrumDrawer = function(buffer){
			this.buffer = buffer;
			this.bufferPosition = 0;
			this.bufferLength = this.buffer.length;
			var pixelWidth = $('#wave').width();
			this.sampleBufferLength = Math.floor(this.bufferLength / pixelWidth);

			$('#spectrum').width(pixelWidth);
			$('#spectrum').height($('#wave').height());
			this.spectrumCanvas = $('#spectrum').get(0);
			this.ctx = this.spectrumCanvas.getContext('2d');
			this.ctx.fillStyle = '#f00';
			this.ctx.font = 'bold 12px sans-serif';
			this.ctx.textBaseline = 'bottom';

			this.drawSpectrum = function(){

				var dataArray = new Uint8Array(this.offlineAnalyser.frequencyBinCount);
				this.offlineAnalyser.getByteFrequencyData(dataArray);

				this.ctx.clearRect(0, 0, this.spectrumCanvas.width, this.spectrumCanvas.height);
				var percent = this.bufferPosition/this.bufferLength*100;
				this.ctx.fillText(this.bufferPosition+' / '+this.bufferLength+'('+percent+'%)', this.bufferPosition/this.sampleBufferLength, 100);

				this.run();
			};

			this.getFrequencyData = function(smallBuffer){
				var that = this;
				var offlineAc = new OfflineAudioContext(
					smallBuffer.numberOfChannels,
					smallBuffer.length,
					smallBuffer.sampleRate
				);

				this.offlineAnalyser = offlineAc.createAnalyser();

				var offlineSource = offlineAc.createBufferSource();
				offlineSource.buffer = smallBuffer;
				offlineSource.connect(this.offlineAnalyser);
				this.offlineAnalyser.connect(offlineAc.destination);

				offlineSource.start();

				offlineAc.startRendering().then(function(){
					that.drawSpectrum();
				});


			};

			this.run = function(){
				if(this.bufferPosition < this.bufferLength){
					var audioCtx = new AudioContext();
					var sampleBuffer = audioCtx.createBuffer(this.buffer.numberOfChannels, this.sampleBufferLength, this.buffer.sampleRate);
					var bufferArray = null;
					for(var c = 0; c < this.buffer.numberOfChannels; c++){
						bufferArray = this.buffer.getChannelData(c);
						bufferArray = bufferArray.slice(this.bufferPosition, this.bufferPosition + this.sampleBufferLength);
						sampleBuffer.copyToChannel(bufferArray, c);
					}

					this.getFrequencyData(sampleBuffer);
					this.bufferPosition = this.bufferPosition + this.sampleBufferLength;
					audioCtx.close();
					if(this.bufferPosition/this.bufferLength > .6){
						var pause;
					}

				}
			};
		};