[tbb-bugs] #29859 [Applications/Tor Browser]: Playing videos on Twitter is not working and freezing the mobile browser

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#29859: Playing videos on Twitter is not working and freezing the mobile browser
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 Reporter:  gk                                   |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:  new
 Priority:  High                                 |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-mobile, GeorgKoppen201903,       |  Actual Points:
  TorBrowserTeam201903, tbb-8.5-must             |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by sysrqb):

 Replying to [comment:7 gk]:
 > Replying to [comment:6 sysrqb]:
 > > Okay, I dug into this a little today. This is coming from Fennec's
 support for HLS (HTTP Live Streaming) via the vendored exoplayer2 library.
 > >
 > > Three easy solutions I see:
 > > 1. Disable `MOZ_ANDROID_HLS_SUPPORT` (we can change the default value
 in `mobile/android/moz.configure`)
 > > 2. Change the returned value in
 `dom/media/DecoderTraits.cpp::CanHandleMediaType()` for HLSDecoder from
 `CANPLAY_MAYBE` -> `CANPLAY_NO`.
 > > 3. Disable the `media.hls.enabled` pref on Android.
 >
 > I think there is no big difference between 1) and 3) given that
 `HLSDecoder::IsSupportedType(aType)` is doing `return IsEnabled() &&
 DecoderTraits::IsHttpLiveStreamingType(aContainerType);` and `IsEnabled()`
 is checking the pref. The advantage of 1) is that we don't bundle the
 whole exoplayer stuff in the first place which would would give us an .apk
 which is slightly smaller. Actually, looking at: https://hg.mozilla.org
 /mozilla-central/rev/9545b9df0c6d it seems both was used to treat HLS
 support appropriately. We should do the same I guess.
 >
 > Somewhat orthogonal:
 https://bugzilla.mozilla.org/show_bug.cgi?id=1371247 makes me itch + that
 the exoplayer shipped is rather old. I wonder whether there were some
 security vulnerabilities fixes meanwhile (I almost bet that there were).

 Good points.

 https://bugzilla.mozilla.org/show_bug.cgi?id=1341990#c20 for background,
 and https://bugzilla.mozilla.org/show_bug.cgi?id=1341990#c109 for worry.

 >
 > That said: I am not sure I understand your concerns regarding 1) (be it
 with or without 3) ). Are you concerned the exoplayer library is used for
 something other than HLS as well and we would therefore run into the same
 problems? Or that we just discover other hangs/freezes because we run into
 similar issues when trying to use a different media handler?

 My concern is the latter - that fennec tries handling the content with
 another handler. I don't know if this would happen, but when I skimmed the
 code it seems possible.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29859#comment:8>
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