<!DOCTYPE html>
<html>

<head>
  <script src="../resources/js-test.js"></script>
  <script src="resources/compatibility.js"></script>
  <script src="resources/audio-testing.js"></script>
</head>

<body>
  <script>
    description('AudioBufferSourceNode: test the "zero" playbackRate.');
    window.jsTestIsAsync = true;

    // Sample rate should be power of 128 to observe the change of AudioParam at
    // the beginning of rendering quantum. (playbackRate is k-rate) This is the
    // minimum sample rate in the valid sample rate range.
    var sampleRate = 4096;

    // The render duration in seconds, and the length in samples.
    var renderDuration = 1.0;
    var renderLength = renderDuration * sampleRate;

    var context = new OfflineAudioContext(1, renderLength, sampleRate);
    var audit = Audit.createTaskRunner();


    // Task: Render the actual buffer and compare with the reference.
    audit.defineTask('synthesize-verify', function (done) {
      var ramp = context.createBufferSource();
      var rampBuffer = createLinearRampBuffer(context, renderLength);
      ramp.buffer = rampBuffer;

      ramp.connect(context.destination);
      ramp.start();

      // Leave the playbackRate as 1 for the first half, then change it
      // to zero at the exact half. The zero playback rate should hold the
      // sample value of the buffer index at the moment. (sample-and-hold)
      ramp.playbackRate.setValueAtTime(1.0, 0.0);
      ramp.playbackRate.setValueAtTime(0.0, renderDuration / 2);

      context.startRendering().then(function (renderedBuffer) {
        var data = renderedBuffer.getChannelData(0);
        var rampData = rampBuffer.getChannelData(0);
        var half = rampData.length / 2;
        var passed = true;

        for (var i = 1; i < rampData.length; i++) {
          if (i < half) {
            // Before the half position, the actual should match with the
            // original ramp data.
            if (data[i] !== rampData[i]) {
              passed = false;
              break;
            }
          } else {
            // From the half position, the actual value should not change.
            if (data[i] !== rampData[half]) {
              passed = false;
              break;
            }
          }
        }

        if (passed) {
          testPassed('The zero playbackRate held the sample value correctly.');
        } else {
          testFailed('The zero playbackRate should hold the sample value. ' +
            'Expected ' + rampData[half] + ' but got ' + data[i] + ' at the index ' +
            i + '.');
        }
      }).then(done);
    });

    audit.defineTask('finish', function (done) {
      finishJSTest();
      done();
    });

    audit.runTasks(
      'synthesize-verify',
      'finish'
    );

    successfullyParsed = true;
  </script>
</body>

</html>