There are some requirement that have to be met by a player if it's to
work with juke.

1) If the player uses multiple processes (many do). It have to return
an error code from its main process if it fails to open an audio
device. The error code must have at least one of the lower eight bits
set.

2) The player must exit cleanly if an audio device is busy.

3) The player must be able to handle the SIGSTOP and SIGCONT signals.

4) The player must exit on SIGTERM (I figure most does).

Player		Problem		Comment
======		=======		=======
amp		1		Can be used with the flag -nobuffer
mikmod		2
xmp		3
bplay		other		Gets "semget: No space left on device"
                                messages after using the program for a while.

mpg123		ok
psgplay		ok
play		ok		play is a shell script front-end to sox