[FFmpeg-user] Cutting out part of a video does not work

[Peter White]

On Sat, Mar 27, 2021 at 09:13:10AM +0100, Bo Berglund wrote:
> On Sat, 27 Mar 2021 02:50:13 +0100, Peter White <peter.white at posteo.net> wrote:
> 
> >> I tested your command ona typical video file and found that the output looks
> >> basically like this:
> >> 
> >> [FRAME]
> >> best_effort_timestamp_time=3900.000000
> >> [/FRAME]
> >> [FRAME]
> >> best_effort_timestamp_time=3905.000000
> >> [/FRAME]
> >> [FRAME]
> >> best_effort_timestamp_time=3910.000000
> >> [/FRAME]
> >> [FRAME]
> >> best_effort_timestamp_time=3915.000000
> >> [/FRAME]
> >> 
> >> It seems like there are "frames" at every 5 seconds.
> >
> >Not to be picky, but there are certainly very many more frames. The
> >distinction is between *keyframes* and everything else called a frame.
> >
> Of course this is not the entire output! It streams past at high speed so covers
> many many pages.

That I did understand. I just wanted to be extra clear that there most
certainly are many more *non-key* frames between those keyframes listed
above, usually motion pictures have at least 24 frames per second.

> But it all looks the same with the time incrementing at exactly 5 seconds...

Looks like someone took extra care to have a static keyframe interval.
One can do that. With default codec options x264 won't produce such
output though.


Cheers,
Peter