test.prototype.start = function()

in 2019/media/playbackperfTest.js [59:102]
43 lines of code
2 McCabe index (conditional complexity)

  test.prototype.start = function(runner, video) {
    var ms = new MediaSource();
    var audioStream = Media.AAC.Audio1MB;
    var videoSb;
    var audioSb;
    var totalDecodedFrames = 0;
    var videoPerfMetrics = new VideoPerformanceMetrics(video);
    if (!videoPerfMetrics.supportsVideoPerformanceMetrics()) {
      runner.fail('UserAgent needs to support ' +
                  '\'video.getVideoPlaybackQuality\' or the combined ' +
                  '\'video.webkitDecodedFrameCount\'' +
                  'and video.webkitDroppedFrameCount to execute this test.');
    }
    ms.addEventListener('sourceopen', function() {
      videoSb = ms.addSourceBuffer(videoStream.mimetype);
      audioSb = ms.addSourceBuffer(audioStream.mimetype);
    });
    video.src = window.URL.createObjectURL(ms);

    var videoXhr = runner.XHRManager.createRequest(
        videoStream.src, function(e) {
      videoSb.appendBuffer(this.getResponseData());
      videoSb.addEventListener('updateend', function() {
        ms.endOfStream();
        video.addEventListener('ended', function() {
          runner.checkEq(
              totalDecodedFrames, frames, 'playbackQuality.totalVideoFrames');
          runner.succeed();
        });
      });
      video.addEventListener('timeupdate', function(e) {
          totalDecodedFrames = videoPerfMetrics.getTotalDecodedVideoFrames();
          test.prototype.status = '(' + totalDecodedFrames + ')';
          runner.updateStatus();
      });
      video.play();
    });
    var audioXhr = runner.XHRManager.createRequest(
        audioStream.src, function(e) {
      audioSb.appendBuffer(this.getResponseData());
      videoXhr.send();
    }, 0, 131100); // audio is longer than video.
    audioXhr.send();
  };