clip video with ffmpeg

sadly, you can't specify frames, but fractions of a second work:

$ ffmpeg -ss 21.5 -i 2024-05-26_00-33-16--cropped.mkv -c copy 2024-05-26_00-33-16--cropped-clipped.mkv

or formated like this, also with -to which is how long after the start to cut the end:

$ ffmpeg -ss 00:00:21 -to 00:00:35 -i 2024-05-26_00-33-16--cropped.mkv -c copy 2024-05-26_00-33-16--cropped-clipped.mkv