I was going great all morning, I even got it to split a video in 5.5 seconds, I ran into files where there is a minimum split range. How do I fix it and why is it only certain files?
Welcome!
mkvmerge can only split on key frames. If there aren’t that many in the first ten seconds, then there’s nothing you can do about it with MKVToolNix.
How come there wasn’t an issue with the other files earlier?
They probably contained more full key frames (full as in, not depending on prior pictures as in open GOP structures). I mean… I can only guess, I don’t have your files on hand to actually check.
When I encountered this issue with MKVtoolnix, I had success with Lossless Cut: