Convert high frame video to slow motion video I recorded a "slow-motion" video with my Android phone and transferred it to my Windows computer. Now I have an MP4 file with a frame-rate of 240 fps. But when I play the video, it plays at normal speed.  I want to create a video that I can upload to YouTube or Facebook that plays at 1/8 speed (30 fps).

I thought I could do that with the free Movie Maker that comes with Windows. But when I select 1/8 speed it comes out chunky. It looks like the software converted the video to 30 fps when it loaded, and is now playing back that 30 fps video at 1/8 speed.  I'm guessing that Movie Maker can't do what I want.

How do I create a video so that when someone plays that video they see it in slow-motion?
You can use ffmpeg, a free command-line tool, to do this:

ffmpeg -i input.mp4 -vf setpts=8*PTS -r 30 -crf 18 output.mp4


This slows down the video 8 times and output is 30 FPS.