deo.videoTracks, "addtrack");
                      sourceBufferAudio.appendBuffer(dataAudio);
                      sourceBufferVideo.appendBuffer(dataVideo);

                      test.waitForExpectedEvents(function()
                      {
                          assert_equals(mediaSource.activeSourceBuffers.length, 2,
                            "activeSourceBuffers list updated when tracks are loaded");
                          assert_equals(sourceBufferAudio.audioTracks.length, 1,
               