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