How can you make a time-lapse with FFmpeg on ubuntu? And I don't mean converting a video into a time-lapse. I mean recording your laptop screen at a sped-up pace.
You can use the setpts filter.
ffmpeg -framerate 60 -video_size 1280x720 -f x11grab -i :0 -vf "setpts=0.5*PTS" output.mp4