[Kdenlive-devel] speed effect

Mikko Rapeli mikko.rapeli at iki.fi
Thu Nov 26 12:32:50 UTC 2009

On Thu, Nov 26, 2009 at 04:11:14AM -0800, Dan Dennedy wrote:
> > Could the speed effect be applied to the original file with original fps
> > and convert to project p30 after playing faster/slower?
> Sorry, not in the near term. Currently, non-speed-effect frame rate
> handling is done within the ffmpeg plugin. I would have to remove that
> and rely entirely upon something like the speed effect, which as you
> know does not support audio at the moment. So, this is not some simple
> bug fix, but a major rework.

Ok, then I guess I need to slow down the p60 clips to p30 before handing
them to kdenlive. Do you know a way to set fps without re-encoding the
content, and maybe also set audio track sample rate to 22050 hz too?

Maybe this would do it:

$ ffmpeg -i orig.mp4 -vcodec copy -acodec copy -r 30 -ar 22050 test.mp4

Or maybe not, since mplayer trust the codec frame rate, though ffmpeg
and ffplay only complain:

$ ffmpeg -i testi.mp4 
    Seems stream 0 codec frame rate differs from container frame
    rate: 120000.00 (120000/1) -> 59.94 (60000/1001)
    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'testi.mp4':
      Duration: 00:00:19.0, start: 0.000000, bitrate: 15743 kb/s
    Stream #0.0(eng): Video: h264, yuv420p, 1280x720 [PAR 0:1 DAR 0:1], 59.94 tb(r)
    Stream #0.1(eng): Audio: mpeg4aac, 48000 Hz, stereo
    Must supply at least one output file

Will need to see how this works out with kdenlive.

It would be nice if I could just edit the frame and audio rate clip
properties in the kdenlive GUI.


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