[FFmpeg-user] filter for changing frame rate

Carl Eugen Hoyos ceffmpeg at gmail.com
Mon May 20 12:24:16 EEST 2019

Am Mi., 15. Mai 2019 um 14:10 Uhr schrieb Daniel Oberhoff via
ffmpeg-user <ffmpeg-user at ffmpeg.org>:
> > On 13 May 2019, at 13:40, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> >
> > Am Mo., 13. Mai 2019 um 13:36 Uhr schrieb Daniel Oberhoff via
> > ffmpeg-user <ffmpeg-user at ffmpeg.org>:
> >>
> >>> You can not.
> >>
> >> I am curious what exactly the hindrance is. As I understand at
> >> least mp4 there is not really a concept of frame rate in the file
> >> and in theory every frame can have a different „rate“, defined
> >> solely by pts.
> >
> > FFmpeg's mp4 muxer does not support variable frame rate.
> Oh, how so? From what I understand about mp4 it does not even
> contain frame rate in the metadata.

> For us this effectively means we cannot use mp4, since some
> of our sources are not very stable in their frame timing.

Patch welcome, consider to contact Baptiste Coudurier.

> So does the muxer ignore the incoming frame pts and just
> imprint monotonic pts with the given frame rate?

No, it (allegedly) writes invalid files if you send it vfr frames.

Carl Eugen

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