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

[Tor Bug Tracker & Wiki]

#29120: Default value of media.cache_size (0) causes some media to load extremely
slowly or become unplayable
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 Reporter:  QZw2aBQoPyuEVXYVlBps      |          Owner:  tbb-team
     Type:  defect                    |         Status:  new
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:                            |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:                            |        Sponsor:
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Comment (by QZw2aBQoPyuEVXYVlBps):

 I've narrowed down the criteria for when this bug happens. It will trigger
 for any video played using the built in media player ({{{<video
 src='...'>}}}) that's filesize is either greater than
 {{{media.memory_cache_max_size}}} (default 8192kb) or unknown (no
 {{{Content-Length}}}).

 I've also established that setting {{{media.cache_size}}} to 0 does
 ''not'' eliminate writing the cache to disk, it simply limits the cache
 file on disk to a few hundred kilobytes and constantly cycles it. Due to
 the nature of how physical storage mediums work, this is likely to be
 functionally equivalent to writing the entire cache to disk without all
 the nonsense inbetween.

 You can observe this yourself with the following command: {{{inotifywait
 -me modify,create,delete,move -r /tmp/ | grep mozilla}}}
 If you open the link in the first post in Tor Browser, you should start
 seeing mozilla temporary files being written to, this is the disk-backed
 MediaCache.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29120#comment:1>
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