[mythtv-commits] Ticket #11371: DVD video sometimes freezes briefly

[MythTV]

#11371: DVD video sometimes freezes briefly
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 Reporter:  peper03@…    |           Type:  Patch - Bug Fix
   Status:  new          |       Priority:  minor
Milestone:  unknown      |      Component:  MythTV - DVD Playback
  Version:  Master Head  |       Severity:  medium
 Keywords:               |  Ticket locked:  0
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 When playing DVDs such as Cars 2 or Brave using VDPAU or with the 'Extra
 audio buffering' option enabled, the video sometimes freezes for a couple
 of seconds.

 This is because the audio timestamp has jumped backwards (from say 20000
 to 47). The condition in AvFormatDecoder::GetFrame ('lastapts < lastvpts +
 100') that determines whether to continue buffering video frames always
 evaluates to true because lastvpts does not get updated until a frame is
 actually processed, which it won't because the video frames keep getting
 buffered.

 This situation continues until either the audio buffer fills up (setting
 'allowedquit' to true and breaking out of the loop) or until the maximum
 number of video frames have been buffered (currently 220).  If the input
 data cannot be read quickly enough (e.g. when reading from a physical DVD
 rather than an image), the picture freezes for around 2 seconds.

 The exact behaviour depends on the input reading speed and the configured
 audio output (7.1 analogue output will fill the audio buffers faster than
 stereo or SPDIF).

 The attached patch detects when the audio timestamp jumps backwards and
 prevents more video frames from being buffered until the frames already in
 the buffer have been processed and the video timestamp has also jumped
 backwards.

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Ticket URL: <http://code.mythtv.org/trac/ticket/11371>
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