I'm embarrassed to ask this, but I hope someone can answer.
How do I combine MKV files?
I've got three files labelled .mkv.001 to .mkv.003
How do I combine these back into a single file?
I don't know it offhand, but I'm sure there's an FFMPEG command to combine or append multiple files. Try searching with those keywords?
Otherwise, well, I know Blender can do video editing, and it also loads MKV files. I've never used it for that myself but I've done audio, and it shouldn't be any different to load some video strips, align them and assign transitions, and tell it to do the thing.
That sounds like what old-fashioned file splitters did back in the time of low bandwhidths and transfer limits.
It would then be just a matter of concatenating one file after the other, irrespective of the original being a video file or any other kind.
In unix the cat command could do it.
In windows you could use programs like HJsplit or Free File Splitter to recombine them
Thanks, everybody. I'll try some of this out this weekend when I have some free time. ^_^