[mythtv-commits] Ticket #11415: video seeking and bookmarks do not work properly for some .avi files
MythTV
noreply at mythtv.org
Thu Feb 21 13:36:01 UTC 2013
#11415: video seeking and bookmarks do not work properly for some .avi files
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Reporter: myth@… | Type: Bug Report - General
Status: new | Priority: minor
Milestone: unknown | Component: MythTV - Video Playback
Version: 0.26-fixes | Severity: medium
Keywords: | Ticket locked: 0
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I have a set of DIVX mpeg4 .avi files generated with mencoder that
mythfrontend seems to have problems with -- seeking and saving bookmarks
show time drifting, especially after playing back the video for a while.
During playback, myth's notion of the current position in the movie drifts
away from the actual position, to the point where after 45 minutes of
playback, if you save a bookmark and resume from it, the video resumes 10
minutes earlier than the previous position. Likewise, attempts to skip
forward / back after 45 minutes of playback end up jumping back 10
minutes.
After analyzing the .avi files, I found that the container shows the frame
rate as 29.97 fps and using 'ffprobe -show_packets', I see video packets
with duration = 0.033 (the appropriate value for 29.97fps), however there
are only actually 24 frames in the stream for every second of PTS time.
Myth is using the (incorrect) container fps value for seeking /
bookmarking decisions. PTS time seems to be accurate which is, I assume,
why playback works fine.
I had this issue with earlier versions of MythTV and I believe it was
resolved by generating a seek table with 'mythcommflag --video', however
this no longer seems to work.
I've had some discussion with Jim Stichnoth about this and he indicated
that changing to use ffmpeg-based seeking in 0.27 should resolve the
problem.
Until 0.27, I have a short-term solution which is to add a '--fixavi'
option to mythtranscode which analyzes the first 5 minutes of the video
and saves the frame rate in the filemarkup table. Then, during playback
of .avi files, if the frame rate is in the filemarkup table, it is used to
override the container frame rate. Patch will be attached soon.
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Ticket URL: <http://code.mythtv.org/trac/ticket/11415>
MythTV <http://code.mythtv.org/trac>
MythTV Media Center
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