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I have a video that is 10 minutes long. I want to convert it to fast motion (the oposite of slow motion. aka time lapse, accelerated motion, undercranking) so that people who watch it will only take 2.5 minutes to watch it. So that would be a 4x(?) speed up. I'm on a Mac, using mpeg streamclip. The video was a screencast (with a lot of waiting time) made with Screenflick, which saved it as a .mov.

To be clear, I dont want to watch it in fast forward or at 4x, I want to export it so it's 4x for everyone (their player playing at 1x). Seems like there should be some frame rate setting, but I cannot figure it out.

This was the closest thing I could find: How can I speed up a video by dropping frames?

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YesCT
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I assume you've read this http://blog.grio.com/2012/01/fast-and-slow-motion-video-with-ffmpeg.html

ffmpeg -i input.mp4 -vf “setpts=0.25*PTS” output.mp4

Offical docs: http://ffmpeg.org/trac/ffmpeg/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video

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  • I used this command on a 33-minute video--and it did indeed condense the video to 1/4 the time--but the original audio remained, allowing the clip to play for the original 33 minutes (most without video). This variant also removes the sound: `ffmpeg -i input.mp4 -vf “setpts=0.25*PTS” -an output.mp4` – Jonathan Wilson Sep 25 '15 at 13:38