[mythtv-commits] Ticket #12396: Mythvideo subtitle timing problem

[MythTV]

#12396: Mythvideo subtitle timing problem
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 Reporter:  ismota@…                 |          Owner:  jyavenard
     Type:  Bug Report - General     |         Status:  new
 Priority:  minor                    |      Milestone:  0.27.5
Component:  MythTV - Video Playback  |        Version:  0.27.4
 Severity:  medium                   |     Resolution:
 Keywords:  subtitle timing          |  Ticket locked:  0
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Comment (by stichnot):

 There's a good chance the timing issues will be solved by generating a
 seektable for the video using "mythcommflag --rebuild".  Can you try that
 and report back?

 Lack of complaints likely due to:
 1. MythTV doesn't record .avi files (i.e. you have to go to extra work to
 import them), so most people don't play them.
 2. Most people don't care about captions/subtitles.

 IIRC, what's happening is that without a seektable, MythTV must ask the
 decoder (ffmpeg) to seek to the desired frame, but ffmpeg only seeks to
 the nearest keyframe, while MythTV believes it is at the exact frame.  If
 keyframes in the .avi file are far apart, subtitles are likely to be out
 of sync.  But if a seektable is present, MythTV seeks to a keyframe, then
 frame-by-frame advances to the desired frame.

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Ticket URL: <https://code.mythtv.org/trac/ticket/12396#comment:2>
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