Note

• When the user leads netflix, plays a video with subtitles and launches the PiP, he will notice that the subs are not displayed in PiP.

Affected versions

• Nightly v102.0a1
• Beta v101.0b5

Affected platforms

• all

Steps to reproduce

1. Launch browser.
2. Load Netflix, play video with subs.
3. Launch PiP

Expected result

• Subtitles are properly displayed in the PiP.

Actual result

• Subtitles aren't being displayed in the PiP.

Regression range

• It is a recent regression between 3rd and 4th of May (nightly v102.0a1). Unfortunately, all the mozregression builds from autoland have failed to play Netflix videos all toghether, were skipped, so a clear regressor could not be determined.
• Mozreg logs:
  Tested mozilla-central build: 2022-05-06 (verdict: b)
  Tested mozilla-central build: 2022-05-04 (verdict: b)
  Tested mozilla-central build: 2022-05-03 (verdict: g)
  Bisecting on mozilla-central [ff375ced - 38697602] - none of these builds played netflix
  Bisecting on autoland [6783c31c - 38697602] - also these

Additional notes
*

The dates in comment 0 correspond to a pushlog that at most is a subset of this pushlog, which includes bug 1767516 which also got uplifted to beta, so would explain why this also broke on beta.

I expect Netflix either changed their subtitle code or some films/series produce differently formatted subtitles than others. We should try to make the adapter more tolerant in what it takes in. Niklas, can you take a look?

These are the detailed mozregression logs. All the next builds mozregression spits out (between the 3rd and 4th of May) aren't testable because they won't play Netflix videos.

Comment on attachment 9276111 [details]
Bug 1768818 - More robust way to find subtitles on Netflix. r=#pip-reviewers!

Beta/Release Uplift Approval Request

• User impact if declined: Users are unable to see subtitles in the PiP window on Netflix
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: No
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: 1. Navigate to Netflix

2. Make sure subtitles are enabled in the original video and make sure media.videocontrols.picture-in-picture.display-text-tracks.enabled is set to true
3. Open a PiP window and confirm the subtitles are visible on the PiP window

• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Not risky because this only affects users watching videos in PiP on Netflix. This is an urgent fix because of the recent release of PiP though.
• String changes made/needed: No
• Is Android affected?: No

https://hg.mozilla.org/mozilla-central/rev/87806f5e6f04

I've verified the fix on Windows 10, MacOS 11.6 and Ubuntu 20.04 using Firefox Nightly 102.0a1 (20220511214930)

Comment on attachment 9276111 [details]
Bug 1768818 - More robust way to find subtitles on Netflix. r=#pip-reviewers!

Approved for 101.0b6.

https://hg.mozilla.org/releases/mozilla-beta/rev/55a2b17a52a4

Comment on attachment 9276111 [details]
Bug 1768818 - More robust way to find subtitles on Netflix. r=#pip-reviewers!

Approved for 100.0.1

https://hg.mozilla.org/releases/mozilla-release/rev/0de67594abb5

Verified fixed on Firefox Beta 101.0b6 (20220512193916)

This fix has also been verified on Release v100.0.1 on Windows 10, Mac OS 11.6.5, Ubuntu 20.04 LTS (X11 Window Protocol), Ubuntu 22.04 LTS (Wayland Window Protocol) and Windows 7. The subs are now displayed in PiP correctly.