calculateTIme.js

.declareMethod('calculateDuration', function (data) {
      // Create a temporary audio element and assign the data to
      // calculate the time duration.
      var gadget = this,
        audioElement = document.createElement('audio');
      audioElement.src = URL.createObjectURL(data);
      return RSVP.Queue()
        .push(function () {
          return promiseEventListener(
            audioElement,
            'loadedmetadata',
            false
          );
        })
        .push(function () {
          gadget.duration = audioElement.duration;
        });
    })