[FFmpeg-devel] [PATCH] Allow 'concat' filter to support inputs with different frame rates

Calvin Walton calvin.walton at kepstin.ca
Wed Mar 8 21:45:13 EET 2017

On Wed, 2017-03-08 at 20:35 +0100, Nicolas George wrote:
> L'octidi 18 ventôse, an CCXXV, Calvin Walton a écrit :
> > Hmm. Setting it to the same as the input value if all inputs match
> > shouldn't be too hard, I think.
> > 
> > In the actual case of inputs with different frame rates, would it be
> > better to use the '1/0' value, or should it attempt to calculate a
> > common framerate that's a multiple of all inputs? (e.g. for 24fps and
> > 30fps inputs, it could pick 120fps).
> > 
> > There's already a TODO listed in the filter code about determining a
> > common timebase rather than using AV_TIME_BASE - if I'm doing the work
> > to find a common framerate, I could probably do this at the same time.
> If the inputs have different frame rates, then concat will be outputting
> variable frame rate, not constant with a common divisor. Therefore 1/0
> is better I think.
> OTOH, printing a message when this happens would probably be useful, and
> in that case, printing the common possible frame rate would be nice. But
> is is not urgent.

On Wed, 2017-03-08 at 20:26 +0100, wm4 wrote:
> I really think if there's no common framerate, it should not pretend
> there is one. Thus setting 1/0 doesn't seem too bad.

Thanks for the feedback Nicolas & wm4. I'll take a look at doing this
in a v2 later this evening.

Calvin Walton <calvin.walton at kepstin.ca>

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