test_seamless_looping_media_element_state.html

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<html>

<head>

<title>Seamless looping media element state</title>

<script src="/tests/SimpleTest/SimpleTest.js"></script>

<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>

<script type="text/javascript" src="manifest.js"></script>

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<script type="application/javascript">

/**

 * This test aims to check if the media element would change its ready state

 * under `HAVE_CURRENT_DATA` when the seamless looping is performed. Because

 * during seamless looping, we should always have current frame.

*/

add_task(async function testSeamlessLoopingMediaElementState() {

  await SpecialPowers.pushPrefEnv({

    set: [

      ["media.seamless-looping-video", true],

],

});

  info(`create video`);

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

  video.loop = true;

  video.src = "gizmo-short.mp4";

  document.body.appendChild(video);

  await video.play();

  info(`test seamless looping multiples times`);

  let MAX_LOOPING_COUNT = 10;

  for (let count = 0; count < MAX_LOOPING_COUNT; count++) {

    await once(video, "seeking");

    // If the video looping is not seamless, when playback reaches to the end,

    // MDSM would trigger a seek in order to get the new frame from the start

    // position. That would notify the media element that the status of the next

    // frame is not available now due to seeking (NEXT_FRAME_UNAVAILABLE_SEEKING)

    // and causes the media element dispatching `waiting` event.

    video.onwaiting = () => {

      ok(false, "should not get waiting event");

    await once(video, "seeked");

    video.onwaiting = null;

    ok(true, `the round ${count} of the seamless looping succeeds`);

});

</script>

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