[FFmpeg-user] Extracting frames from 59.94 FPS video - only every other frame is different

[Moritz Barsnick]

On Mon, Dec 04, 2017 at 14:29:25 +0100, Carl Eugen Hoyos wrote:
> 2017-12-04 14:25 GMT+01:00 Moritz Barsnick <barsnick at gmx.net>:
> >       clear (to me) from the docs.
> 
> Which one?

The decimate filter's practical use isn't clear to me from the docs.

> The mpdecimate filter - as you wrote - produces vfr video
> which may not always be wanted.

I believe that was something I wanted, or could fix with the setpts
filter. I wanted to do stupid minimal motion (change) detection.

OT: Actually, I want a filter which does certain parts of what the
program "motion" does, but not with a camera device, but with an input
video instead. (The advantage of a filter being I could crop the input
first, or omit parts of the timeline, and I could modify it to only
look at certain segements, and so on.) I did have a concept in my head
for what this filter should do, and approx. how, but found to many
filters doing certain elements of this already. I was afraid of
duplicating stuff (though it would have been nice practice), and never
found the spare time.

Moritz