I need to speed up video by a factor of 4x, but do not want to drop the frames and instead average them. I.e. each 4 frames are averaged, and produce 1 output frame. Target frame-rate stays the same, so video is now 4 times faster.

Is there a way to do so in ffmpeg?

  • 3
    Can you be more specific about how they should be "averaged"? What method do you want to use? – LordNeckbeard Oct 5 '15 at 6:09
  • @LordNeckbeard (f1+f2+f3+f4)/4 - simple averaging. So each resulting frame have faint traces of the movement on all sub-frames. – BarsMonster Oct 5 '15 at 11:32
  • @BarsMonster I doubt ffmpeg can do this. Have you seen this effect done another way? Do you know what it actually looks like? – Jim Mack Oct 5 '15 at 15:08
  • @JimMack I currently did that manually in VirtualDub, they have interpolate filter, with 0.5x interpolation it does correctly average 2 frames. Here is the result : youtube.com/watch?v=8zrws5CGWsI One can see that each frame has movement of 2 subframes, so it is slightly smoother. But doing so in a cmdline would be much faster in the future. – BarsMonster Oct 5 '15 at 18:16
  • slowmoVideo may be worth a try, but I don't know if it has a cli. The FFmpeg framerate filter appears to perform interpolation, but it does not seem to fit your needs. – LordNeckbeard Oct 5 '15 at 21:26
up vote 9 down vote accepted

ffmpeg with this filterchain does it:

ffmpeg -i input -vf "tblend=average,framestep=2,tblend=average,framestep=2,setpts=0.25*PTS" -r srcfps -{encoding parameters} output

srcfps should be replaced with your input's framerate.

  • 1
    Also tried for x16 using "tblend=average,framestep=2,tblend=average,framestep=2,tblend=average,framestep=2,tblend=average,framestep=2,setpts=0.0625*PTS" – BarsMonster Oct 15 '16 at 15:31

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