export function PCMPlayer(option)
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{
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this.init(option);
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}
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PCMPlayer.prototype.init=function(option)
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{
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var defaults={
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encoding: '16bitInt',
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channels:1,
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sampleRate:8000,
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flushingTime:1000
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};
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this.option=Object.assign({},defaults,option);
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this.samples=new Float32Array();
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this.flush=this.flush.bind(this);
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this.interval=setInterval(this.flush,this.option.flushingTime);
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this.maxValue=this.getMaxValue();
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this.typedArray=this.getTypedArray();
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this.createContext();
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};
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PCMPlayer.prototype.getMaxValue=function()
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{
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var encodings={
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'8bitInt': 128,
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'16bitInt':32768,
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'32bitInt':2147483648,
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'32bitFloat':1
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}
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return encodings[this.option.encoding]?encodings[this.option.encoding]:encodings['16bitInt'];
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};
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PCMPlayer.prototype.getTypedArray=function()
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{
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var typedArrays={
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'8bitInt': Int8Array,
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'16bitInt':Int16Array,
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'32bitInt':Int32Array,
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'32bitFloat':Float32Array
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}
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return typedArrays[this.option.encoding]?typedArrays[this.option.encoding]:typedArrays['16bitInt'];
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};
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PCMPlayer.prototype.createContext=function()
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{
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this.audioCtx=new (window.AudioContext||window.webkitAudioContext)();
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this.gainNode=this.audioCtx.createGain();
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this.gainNode.gain.value=1;
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this.gainNode.connect(this.audioCtx.destination);
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this.startTime=this.audioCtx.currentTime;
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};
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PCMPlayer.prototype.isTypedArray=function(data)
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{
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return (data.byteLength&&data.buffer&&data.buffer.constructor==ArrayBuffer);
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};
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PCMPlayer.prototype.feed=function(data)
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{
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if(!this.isTypedArray(data)) return;
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data=this.getFormatedValue(data);
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var tmp=new Float32Array(this.samples.length+data.length);
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tmp.set(this.samples,0);
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tmp.set(data,this.samples.length);
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this.samples=tmp;
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};
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PCMPlayer.prototype.getFormatedValue=function(data)
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{
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var data=new this.typedArray(data.buffer),
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float32=new Float32Array(data.length),
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i;
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for(i=0; i<data.length; i++)
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{
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float32[i]=data[i]/this.maxValue;
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}
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return float32;
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};
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PCMPlayer.prototype.volume=function(volume)
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{
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this.gainNode.gain.value=volume;
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};
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PCMPlayer.prototype.destroy=function()
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{
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if(this.interval)
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{
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clearInterval(this.interval);
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}
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this.samples=null;
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this.audioCtx.close();
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this.audioCtx=null;
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};
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PCMPlayer.prototype.flush=function()
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{
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if(!this.samples.length) return;
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var bufferSource=this.audioCtx.createBufferSource(),
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length=this.samples.length/this.option.channels,
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audioBuffer=this.audioCtx.createBuffer(this.option.channels,length,this.option.sampleRate),
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audioData,
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channel,
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offset,
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i,
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decrement;
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for(channel=0; channel<this.option.channels; channel++)
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{
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audioData=audioBuffer.getChannelData(channel);
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offset=channel;
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decrement=50;
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for(i=0; i<length; i++)
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{
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audioData[i]=this.samples[offset];
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/* fadein */
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if(i<50)
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{
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audioData[i]=(audioData[i]*i)/50;
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}
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/* fadeout*/
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if(i>=(length-51))
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{
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audioData[i]=(audioData[i]*decrement--)/50;
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}
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offset+=this.option.channels;
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}
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}
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if(this.startTime<this.audioCtx.currentTime)
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{
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this.startTime=this.audioCtx.currentTime;
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}
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//console.log('start vs current '+this.startTime+' vs '+this.audioCtx.currentTime+' duration: '+audioBuffer.duration);
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bufferSource.buffer=audioBuffer;
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bufferSource.connect(this.gainNode);
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bufferSource.start(this.startTime);
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this.startTime+=audioBuffer.duration;
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this.samples=new Float32Array();
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};
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PCMPlayer.prototype.getTimestamp=function()
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{
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if(this.audioCtx)
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{
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return this.audioCtx.currentTime;
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}
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else
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{
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return 0;
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}
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};
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PCMPlayer.prototype.play=function(data)
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{
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if(!this.isTypedArray(data))
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{
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return;
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}
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data=this.getFormatedValue(data);
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if(!data.length)
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{
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return;
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}
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var bufferSource=this.audioCtx.createBufferSource(),
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length=data.length/this.option.channels,
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audioBuffer=this.audioCtx.createBuffer(this.option.channels,length,this.option.sampleRate),
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audioData,
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channel,
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offset,
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i,
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decrement;
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for(channel=0; channel<this.option.channels; channel++)
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{
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audioData=audioBuffer.getChannelData(channel);
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offset=channel;
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decrement=50;
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for(i=0; i<length; i++)
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{
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audioData[i]=data[offset];
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/* fadein */
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if(i<50)
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{
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audioData[i]=(audioData[i]*i)/50;
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}
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/* fadeout*/
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if(i>=(length-51))
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{
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audioData[i]=(audioData[i]*decrement--)/50;
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}
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offset+=this.option.channels;
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}
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}
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if(this.startTime<this.audioCtx.currentTime)
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{
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this.startTime=this.audioCtx.currentTime;
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}
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//console.log('start vs current '+this.startTime+' vs '+this.audioCtx.currentTime+' duration: '+audioBuffer.duration);
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bufferSource.buffer=audioBuffer;
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bufferSource.connect(this.gainNode);
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bufferSource.start(this.startTime);
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this.startTime+=audioBuffer.duration;
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};
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PCMPlayer.prototype.pause=function()
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{
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if(this.audioCtx.state==='running')
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{
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this.audioCtx.suspend()
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}
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}
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PCMPlayer.prototype.resume=function()
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{
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if(this.audioCtx.state==='suspended')
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{
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this.audioCtx.resume()
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}
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}
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