MKV do MP4 Linux
ffmpeg -i input.mkv -codec copy output.mp4
Old-fashioned Opossum
ffmpeg -i input.mkv -codec copy output.mp4
ffmpeg -i "file.mkv" -codec copy -strict -2 "file.mp4"
cool way to convert is cloudconvert.com honestly
ffmpeg -i LostInTranslation.mkv -codec copy LostInTranslation.mp4
OBS > File > Remux Recordings