via the standard audio interfaces is redirected back to userland as raw
PCM data on /dev/padN.
One example usage is to stream audio to an AirTunes compatible device using
rtunes (http://www.nazgul.ch/dev_rtunes.html), ie:
$ rtunes - < /dev/pad0
$ mpg123 -a /dev/sound1 blah.mp3
Another option is to capture audio output from eg. Real Player, by simply
instructing Real Player to output to /dev/sound1, and running:
$ cat /dev/pad0 > blah.pcm
23526fe3a9