[FFmpeg-trac] #6971(undetermined:new): ffmpeg drops frames after deinterlacing

FFmpeg trac at avcodec.org
Sat Nov 24 00:11:52 EET 2018

#6971: ffmpeg drops frames after deinterlacing
             Reporter:  CaryKnoop    |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  cuvid        |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0

Comment (by oromit):

 The issue is that the timebase will be 1/25 for 25i content. So it's
 impossible to represent 50 fps in that timebase, but a decoder can't
 change the timebase.
 Hence the -r 50 on input, to trick ffmpeg.c into using a 1/50 timebase.
 Results of trying to double the framerate on a timebase where +1 is
 already too much are pretty much random.

 This jumping is weird though, and I can't reproduce it here. I suspect the
 source material is already broken like that and it just carries through.

 Keep in mind that mpeg2 is most likely not a well tested format, and
 nvidias parser also is far from perfect for common formats. So it messing
 up the re-ordering is not out of the question.

Ticket URL: <https://trac.ffmpeg.org/ticket/6971#comment:28>
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