[tbb-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:                      |          Owner:  tbb-team
  QZw2aBQoPyuEVXYVlBps          |
     Type:  defect              |         Status:  new
 Priority:  Medium              |      Component:  Applications/Tor Browser
  Version:                      |       Severity:  Normal
 Keywords:                      |  Actual Points:
Parent ID:                      |         Points:
 Reviewer:                      |        Sponsor:
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 It seems this value was defaulted to 0 after this ticket:
 https://trac.torproject.org/projects/tor/ticket/10237

 The issue this causes can be seen on this page:
 https://livestreamfails.com/post/28515

 If you open this link in a default configured Tor Browser (I'm using
 v8.0.4), and open the network inspector (CTRL+SHIFT+E), you will see the
 media file is constantly being re-requested, downloading the file a few
 hundred kilobytes at a time using range requests.

 This causes the video to load extremely slowly. If the HTTP server does
 not support range requests, the video will seemingly become unplayable in
 the native player.

 This kind of behavior could also be seen as abusive or mistaken as DoS
 related traffic by website operators, since it is not typically how
 browsers download media.

 Setting media.cache_size to the default Firefox value of 512000 fixes
 this, it may also work with a lower cache size, but I've only tried the
 default Firefox value. I suppose it also may bring back the original issue
 of the media cache being stored on disk, that ticket is from 5 years ago
 though, so I'm sure if that situation has changed.

 This bug only seems to affect certain media files, I'm not exactly sure
 what the other factors are in triggering the behavoir.

 This bug also exists in the latest stable version of Firefox if you set
 the media.cache_size to 0, I suppose it's rarely encountered though since
 the default is much higher.

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