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

FFmpeg trac at avcodec.org
Sat Nov 24 01:31:17 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 malakudi):

 Replying to [comment:28 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
 > 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.

 Input of last log with the jumping frame timestamps is a standard h264
 1080i dvb-t transmission here in Greece. You can get a small part of it
 from my vps server,

 ffmpeg-3.3.9 does not show this jumping and that's why it works there with
 -r 50 on output. Full command I do this test is:
 ./ffmpeg-git -debug_ts -hwaccel cuvid -c:v h264_cuvid -deint adaptive -f
 mpegts -i input_1080i.ts -aspect 16:9 -flags:v +cgop -vcodec h264_nvenc -g
 200 -refs 4 -bf 3 -profile:v high -level 4.2 -c:a aac -ac 2 -b:a 128k -r
 50 -f mpegts -y /dev/null 2>&1 | egrep ^filter

Ticket URL: <https://trac.ffmpeg.org/ticket/6971#comment:29>
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