Simply multiply by the reciprocal of the speed factor.
1 2 |
ffmpeg -i input.mkv -filter:v "setpts=PTS/60" output.mkv |
This does not affect the audio speed. Use -an
to not include audio in the output.
A faster method, but which can have unexpected results with audio (pauses or async):
1 2 |
ffmpeg -itsscale 0.01666 -i input.mkv -c copy output.mkv |
where 0.01666
is 1/60
in decimal representation.