>>27622757https://ffmpeg.org/documentation.html RTFMOr get the UNIX manual page and Ctrl+F the flags.
The crop filter is a bit tricky and I more than once smashed my table but it's quite easy once you understand
width:height:x:y
0 for x and y means top left iirc, so if you replace them by the video resolution you end up cropping from the bottom right