Currently, mp3.rom will start playing a hardcoded file.
On Linux, when the uxn11 process ends the mpg123 process will also be
killed. The code to do this isn't portable, so on BSD/etc. there will
be an orphan process left around if uxn11 is killed.
(In both cases an emulator-driven exit will end the subprocess.)
The mp3 ROM will currently interpret each line of `mpg123 -R` output,
and dispatch to the appropriate subroutine. None of these do anything
yet.
~d6