I found this example
ffmpeg -i input.mkv -filter:v "setpts=0.5*PTS" output.mkv
but I have a video I want to speed up by 60 times, not just 2X.
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Simply multiply by the reciprocal of the speed factor.
ffmpeg -i input.mkv -filter:v "setpts=PTS/60" output.mkv
This does not affect the audio speed. Use
-an to ignore audio.
A faster method, but which can have unexpected results with audio (pauses or async):
ffmpeg -itsscale 0.01666 -i input.mkv -c copy output.mkv
1/60 in decimal representation.
If you also want to speed up the audio, you need to do this:
ffmpeg -i input.mkv -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2[a]" -map "[v]" -map "[a]" output.mkv
The command above works if you want to multiply by 2 the speed. If you want to multiply by any
x (between 0 and 2), the parameters become:
ffmpeg -i input.mkv -filter_complex "[0:v]setpts=<1/x>*PTS[v];[0:a]atempo=<x>[a]" -map "[v]" -map "[a]" output.mkv
For instance, if you want to multiply by 1.15, the command is
ffmpeg -i input.mkv -filter_complex "[0:v]setpts=0.87*PTS[v];[0:a]atempo=1.15[a]" -map "[v]" -map "[a]" output.mkv
I wanted to speed up the audio and video many times beyond 2x too. For 60x speed, do the following. It may be a bit verbose, but it works great. The problem is that atempo cannot be greater than two or less than 0.5, so we must repeat atempo many times to get the sound to the rate that we want it.
ffmpeg -i input.mkv -filter:v "setpts=PTS/60" -filter:a "atempo=2,atempo=2,atempo=2,atempo=2,atempo=2,atempo=1.875" output.mkv
Press Ctrl+Shift+I, and click the "console" tab. Then, copy and paste this code into the console. In Chrome, click just right of the blue arrow. In Firefox, type
allow pasting into the console to allow copy'n'paste. Then, press Enter run the following JS code to generate other speeds. The code also works with slowing down the video.
var speed=eval(prompt("Enter speed up or slowdown factor (>1 is speedup, " + "<1 is slowdown; can use 1/X for slowdown): ", "60")); var k=speed, audio=""; while (2 < k && k === k) k /= 2, audio+="atempo=2,"; while (k < 0.5 && k === k) k *= 2, audio+="atempo=0.5,"; audio += "atempo=" + k; prompt( "Copy the following commandline: ", 'ffmpeg -i input.mkv -filter:v "setpts=PTS/' + speed + '" -filter:a "' + audio + '" output.mkv' );
This code will prompt you to enter a value and present you with the result. Entering
60 yields a 60X speedup, entering
0.1 yields a 10X slowdown, and entering
1/30 yields a 30X slowdown. I hope this helps.