Mkvtoolsnix
From wikinotes
Tools to interact with MKV files - splitting/merging them by chapter, etc.
Install
pacman -S mkvtoolsnix-cli mkvtoolsnix-gui
Usage
mkvmerge input.mkv --split chapters:all -o out.mkv # split mkv at every chapter mark mkvmerge -o 1.mkv 1-1.mkv + 1-2.mkv + 1-3.mkv # merge files back into single file
