I've tried to create a profile in kdenlive that uses -codec copy (and -acodec copy -vcodec copy) (in the mlt form, of course), but it doesn't work. The former just uses the default codec and the latter crashes. Of course I'm only attempting to create raw cuts with it.

I looked around for a better how-to and have found that there is consensus that this is not possible with kdenlive. But why is that? It seems like it should be trivial to implement. Or is it possible and I'm just doing it wrong?