Debugging video jerking problem

[Nicolas Dufresne]

Le ven. 7 déc. 2018 05 h 11, Wolfgang Grandegger <wg at grandegger.com> a
écrit :

> Hello,
>
> hmm, the long story: My camera records AVCHD video with 1920x1080 pixel
> and 50 frames/sec. Then I convert it to an 50 FPS AVI raw video using:
>
>   $ ffmpeg -i input.mts -vcodec rawvideo -y output-50fps.avi
>
> To get the same video running at 60 FPS I do:
>
>   $ ffmpeg -i input.mts -filter:v "setpts=0.83333333*PTS" \
>          -r 60 -vcodec rawvideo -y output-60fps.avi
>
> I assume that this video uses the same raw frames just with different
> time stamps. What do I miss?
>

Understand that this could also be the threshold your receiving socket can
carry with its current setting. It cost nothing to try and increase it, see
buffer-size on udp-sink and sysctl net.core.rmem_max setting of your Linux
kernel (if Linux is your host OS).


> Thanks,
>
> Wolfgang.
>
> Am 07.12.2018 um 10:13 schrieb Ian Davidson:
> > You start with a video recorded at 50 fps and convert it to 60 fps.  So,
> > for each 5 frames of the original video, something has to 'invent' 1
> > extra frame.  It is never going to be 'perfect'.
> >
> >
> > On 06/12/18 19:50, Wolfgang Grandegger wrote:
> >>
> >> Not sure if I understand you correctly. I do not change FPS on the fly.
> >> I convert my MJPEG video from 50 to 60 FPS on the remote side with
> >>
> >>    $ ffmpeg ... -filter:v "setpts=0.83333333*PTS" -r 60 ...
> >>
> >> and then send it to the network. The video with 50 FPS is recorded
> >> and displayed fine. The one with 60 FPS causes jerking on the display.
> >> The jerking is also visible on the recorded video... hm, can I assume
> >> that the "rtpjitterbuffer" calculated jerky timestamps then?
> >>
> >
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