Note

• When the user loads a long enough TikTok video, unmutes, enables PiP and then double-clicks the Pip window to go into full screen, he will notice that the video will also pause when it shouldn't.

Affected versions

• Nightly v98.0a1
• Beta v97.0b4

Affected platforms

• all

Steps to reproduce

1. Load https://www.tiktok.com/foryou?is_copy_url=1&is_from_webapp=v1
2. Scroll to a video that's long enough to have PiP.
3. Unmute (not necessary, but makes the issue stand out)
4. Activate PiP
5. Double-click the PiP window to enter full screen.
   actual: goes fullscreen AND pauses the video
   expected: goes fullscreen and continues playing

Expected result

• Goes fullscreen and continues playing.

Actual result

• Goes fullscreen AND pauses the video.

Regression range

• Appears to be a regression from Fx97:
  2022-01-17T20:45:30.961000: DEBUG : Found commit message:
  Bug 1732736 - Enable window occlusion on Nightly on Windows r=jrmuizel,gfx-reviewers
  Differential Revision: https://phabricator.services.mozilla.com/D127366
  2022-01-17T20:45:30.961000: DEBUG : Did not find a branch, checking all integration branches
  2022-01-17T20:45:30.963000: INFO : The bisection is done.

Additional notes

• This issue appears to only reproduce on the main monitor (in case of more than one monitor connected to the machine).
• It does not occur in with Youtube videos.

Hi, Bodea Daniel. Thank you for reporting. I am going to look into the bug.

video's of tiktok stopped playback when its Tab is hidden(not front Tab). It seems to be related. When window is occluded, front Tab is set as hidden Tab.

PiP video's document visibility still belongs to original Tab. When PiP video becomes fullscreen, the original Tab is set as hidden Tab by window occlusion.

I confirmed that paused Video could be resumed by clicking Play button.

With chrome browser, I did not see PIP icon. It seems that PIP is not enabled on tiktok.com on chrome browser.

I forced to enable PIP on chrome browser by using Picture-in-Picture Extension, PIP video playback was paused when original video's Tab was hidden.

:mconley, can you comment to this bug?

This seems somewhat related to bug 1598654, where the visibility state of the document is being used by the site to make decisions on how the video should behave. Here, it sounds like they pause it. In bug 1598654, a lowering of quality is what happens, but the underlying cause is the same.

One idea we had was to not change the visibility state of a document when any of its video elements are being PiP'd, but that's something we might actually want to have the DOM team weigh in on, since that'd likely have to happen down in DOM code.

98 affected as Window Occlusion was activated to ride the trains in bug 1750491

I cannot reproduce this bug on Windows 10, Ubuntu 20.04, and MacOS Bug Sur. May already be resolved, considering Bug 1755748 and Bug 1598654 are fixed.