test_seamless_looping_not_keep_painting_old_video_frames.html

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<title>Seamless looping test : do not keep painting old video frames</title>

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/**

 * This test is used to ensure that after seeking to EOS directly, video can

 * display its frame sucessfully, not showing the incorrect frame which should

 * be discarded during seeking. The test video contains three seconds white

 * frames [0s-3s] and one second black frames [3s-4s], so after seeking to

 * EOS and start looping video again, video should display white frames, instead

 * of black frames.

*/

add_task(async function testSeamlessLoopingDoNotKeepPaintingOldVideoFrame() {

  info(`create video and play it`);

  const WIDTH = 10, HEIGHT = 10;

  let video = document.createElement('video');

  video.loop = true;

  video.src = "white-3s-black-1s.webm";

  video.width = WIDTH;

  video.height = HEIGHT;

  document.body.appendChild(video);

  await video.play();

  info(`seek to EOS (${video.duration}s) and waiting for looping`);

  video.currentTime = video.duration;

  await once(video, "seeked");

  // We can't control the exact timing when the compositor would render next

  // frame so we wait for the next timeupdate to ensure the media has been

  // moved forward to the place where video should show white frames.

  info(`wait for timeupdate then check the painted frame`);

  await once(video, "timeupdate");

  const canvas = document.createElement('canvas');

  const context = canvas.getContext('2d');

  canvas.width = WIDTH;

  canvas.height = HEIGHT;

  context.drawImage(video, 0, 0, canvas.width, canvas.height);

  const pixelData = context.getImageData(0, 0, WIDTH, HEIGHT).data;

  for (let idx = 0; idx < WIDTH * HEIGHT; idx++) {

    let pixelCount = 4 * idx; // RGBA

    // White frame's RGB value should be [255,255,255]

    is(pixelData[pixelCount + 0], 255, `R should be 255`);

    is(pixelData[pixelCount + 1], 255, `G should be 255`);

    is(pixelData[pixelCount + 2], 255, `B should be 255`);

});

</script>

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