[FFmpeg-user] Dropping 1 frame every n seconds

[Moritz Barsnick]

On Sun, May 31, 2015 at 14:38:02 +0200, Paul B Mahol wrote:
> Dana 31. 5. 2015. 11:46 osoba "Steve" <steve at aatw.com> napisala je:

> > At 25fps, dropping 1 frame would allow the the audio to be pitched/time
> stretched by 4% and dropping 1 frame every 2 seconds would allow for 2%

> See select and framestep filter documentation.

(I may be wrong, but:)

This isn't complete, the video won't play faster after dropping the
frames, due to the timestamps of the retained frames. I think that
after dropping one in N frames, you need to increase the speed using
the setpts filter with a factor of (N-1)/N.

  setpts=24/25*PTS

Just figuring this out from the top of my head, it's late. ;-)

Moritz