[tor-bugs] #29120 [Applications/Tor Browser]: Default value of media.cache_size (0) causes some media to load extremely slowly or become unplayable

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#29120: Default value of media.cache_size (0) causes some media to load extremely
slowly or become unplayable
-------------------------------------------------+-------------------------
 Reporter:  QZw2aBQoPyuEVXYVlBps                 |          Owner:  tbb-
                                                 |  team
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  High                                 |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-disk-leak, tbb-usability-        |  Actual Points:
  website, TorBrowserTeam201902                  |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by QZw2aBQoPyuEVXYVlBps):

 Here is the result of loading a media file where the server gives a "0" as
 the content length:

 {{{
 [45086:Main Thread]: D/MemoryBlockCache 0x7f6f9075b340 MemoryBlockCache()
 MEMORYBLOCKCACHE_ERRORS='InitUnderuse'
 [45086:Main Thread]: D/MemoryBlockCache 0x7f6f9075b340 Init()
 [45086:Main Thread]: D/MediaCache GetMediaCache(0) -> Memory MediaCache
 0x7f6f99e24870
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 opened
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 feeding reader
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 DataStarted: 0
 aLoadID=1 aLength=0
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 at end of stream
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 at end of stream
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 at end of stream
 [Child 45086, MediaPlayback #1] WARNING: Decoder=7f6f92aa1e00
 state=DECODING_METADATA Decode metadata failed, shutting down decoder:
 file /var/tmp/build/firefox-
 4d0f9fa5fdd5/dom/media/MediaDecoderStateMachine.cpp, line 340
 [Child 45086, MediaPlayback #1] WARNING: Decoder=7f6f92aa1e00 Decode
 error: NS_ERROR_DOM_MEDIA_METADATA_ERR (0x806e0006) - static
 mozilla::MP4Metadata::ResultAndByteBuffer
 mozilla::MP4Metadata::Metadata(mozilla::ByteStream*): Cannot parse
 metadata: file /var/tmp/build/firefox-
 4d0f9fa5fdd5/dom/media/MediaDecoderStateMachine.cpp, line 3118
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 at end of stream
 [45086:MediaCache]: D/MediaCache Stream 0x7f6fa8857040 closed
 [45086:Main Thread]: D/MediaCache
 MediaCacheStream::~MediaCacheStream(this=0x7f6fa8857040)
 MEDIACACHESTREAM_LENGTH_KB=0
 [45086:Main Thread]: D/MediaCache ~MediaCache(Memory-backed MediaCache
 0x7f6f99e24870)
 [45086:Main Thread]: D/MemoryBlockCache 0x7f6f9075b340 ~MemoryBlockCache()
 - destroying buffer of size 0; combined sizes now 0
 }}}

 The end result for the user is a "No video with supported format and MIME
 type found." error message on the video. This result seems sane to me.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29120#comment:21>
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