[FFmpeg-user] filter for changing frame rate

[Moritz Barsnick]

On Mon, May 13, 2019 at 14:03:30 +0200, Jon bae wrote:
> Am Mo., 13. Mai 2019 um 13:41 Uhr schrieb Paul B Mahol <onemda at gmail.com>:
> > fps filter duplicates/drops frames, dejudder is specific filter for
> > specific usecase.
> >
> Yes the is right, I don't want any dropping or interpolating. Just setting
> a new fps. But when this is not possible with filters, I have to use the -r
> option.

Isn't "-r" - at least in theory - the same as inserting the fps filter
at the end or the filter chain? [*]

Anyway, if setpts has already changed the actual (PTS-driven)
framerate, then chaining the fps filter should only change the
metadata. Caveat: Only if the input is CFR; otherwise the fps filter
will duplicate/drop to achive CFR.

So what is required here is a filter (or bitstream filter?), which can
change the metadata framerate (and only that), or such an option for
the muxer. Or what am I missing?

BTW, 'setpts=24000/1001/25*PTS' is probably the correct value, assuming
the input has a norm framerate.

Moritz

[*] I recall having read that there are some behavioral differences.