Really recommend a song from Red Dead Redemption II, which is called: THAT’S THE WAY IT IS, composed by Daniel Lanois. The song can be found at https://www.youtube.com/watch?v=HjYLY3BGDY4
I downloaded it and tried to share this beautiful song with my friends and family, in mpeg3 format.
This is the command on Linux to extract mkv to mpeg3 with ffmpeg (love this open-source powerful command on Linux)
find . -type f -name "*.mkv" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -c:a libmp3lame -y "${FILE%.mkv}.mp3";' _ '{}' \;