mono-to-stereo.html

<link rel="import" href="../polymer/polymer.html">

<dom-module id="mono-to-stereo">
  <template>

  </template>

  <script>
    /**
     * An element that provides a simple way of generating stereo sound from audio
     * 
     * Example:
     *    <mono-to-stereo></mono-to-stereo>
     * 
     * @demo demo/index.html
     */
    Polymer({

      is: 'mono-to-stereo',

      properties: {
        /**
         * `input` represents the input mono stream
         */
        input: {
          type: Object,
          notify: true,
          reflectToAttribute: true
        },
        /**
         * `output` represents the output stereo stream
         */
        output: {
          type: Object,
          notify: true,
          reflectToAttribute: true
        },
        /**
         * `outputUrl` represents a url to the output stereo stream
         */
        outputUrl: {
          type: String,
          notify: true,
          reflectToAttribute: true
        }
      },
      attached: function(){
        setTimeout(function(){
          console.log(this.input);
        
          var context =  new (window.AudioContext || window.webkitAudioContext)();
          // var source = context.createMediaStreamSource(this.input);
          
          this.output = context.createMediaStreamDestination();
          
          // split
          var leftClone = context.createMediaStreamSource(this.input.clone()),
          rightClone = context.createMediaStreamSource(this.input.clone());
          
          // pan left
          var panLeft = context.createStereoPanner();
          panLeft.pan.value = -1;
          leftClone.connect(panLeft);
          
          // delay left by 50 ms
          var delay = context.createDelay(100);
          panLeft.connect(delay);
          
          // pan right
          var panRight = context.createStereoPanner();
          panRight.pan.value = 1;
          leftClone.connect(panRight);
          
          // merge
          var merger = context.createChannelMerger(2);
          delay.connect(merger, 0, 0);
          panRight.connect(merger, 0, 1);
          
          merger.connect(this.output);
          
          this.outputUrl = window.URL.createObjectURL(this.output.stream);
        }.bind(this),1000)
        
      }

    });
  </script>
</dom-module>