[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
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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
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.
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, http://207.154.237.57/files/input_1080i.ts
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
}}}
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Ticket URL: <https://trac.ffmpeg.org/ticket/6971#comment:29>
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