mkv
mp4
ffmpeg:
First, convert a file called "software_pres_2020-12-18.mkv" to "prestmptest"
ffmpeg -i software_pres_2020-12-18.mkv prestmptest.mp4
ffmpeg -i vimemacs-2022-08-12_10-44-05.mkv -codec copy vimemacs-in-rst.mp4