[tor-bugs] #28107 [Applications/Tor Browser]: Tor Browser 8.0 turns off VP9 videos when detects low fps

[Tor Bug Tracker & Wiki]

#28107: Tor Browser 8.0 turns off VP9 videos when detects low fps
--------------------------------------+-----------------------------------
 Reporter:  vp9                       |          Owner:  tbb-team
     Type:  defect                    |         Status:  needs_information
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:  tbb-fingerprinting        |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:                            |        Sponsor:
--------------------------------------+-----------------------------------

Comment (by vp9):

 Oh, crap, it's not easy to reproduce starting from a clean 8.0.2. And
 there is nothing obvious in the source code... But the same is for
 #22548... All we have is:
 {{{
   return !mp4supported || !hwsupported || VP9Benchmark::IsVP9DecodeFast();
 }}}
 Then, how come it returns `false` for machines without mp4? Does it check
 for `mp4enabled` instead of `mp4supported`?
 How come it returns `false` for machines without hardware decoding and
 even with hardware acceleration disabled?
 It could be easier to enable vp9 unconditionally, because
 > VP9 software decoding is faster than H.264 software decoding.
  https://bugzilla.mozilla.org/show_bug.cgi?id=1213177#c10
 but as you prefer to deal with all that 'hardware acceleration' mess,
 things become much more complicated, and you have to inspect `hwsupported`
 works correctly in every weird hardware configuration.
 As for `IsVP9DecodeFast()`, it seems it always returns `false` on a first
 run, see https://hg.mozilla.org/releases/mozilla-
 aurora/rev/921e6142e8b9#l1.67, but there also could be more weird e10s-
 related bugs like https://bugzilla.mozilla.org/show_bug.cgi?id=1446931.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28107#comment:3>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online