port for separation audio from video in mp4 file

[Stefan Miklosovic]

hi,

title says it, i downloaded mp4 file by youtube-dl,
but it downloaded video and audio as well. I would
like to separate audio from that file.

i try to find some port in /usr/ports/audio but nothing
reasonable occudred.

i tried "find . -type f -name pkg-descr | xargs grep mp4"
but these were only some "offtopic" programs :)

thank you