[Alsa-user] Obtaining output samples

[Ron C. <ron...@re...>]

Hello,

I was wondering if there is a way to grab the samples that are being 
played through ALSA.  For instance, if I'm playing some audio (song) 
with aplay, or maybe from xmms, I would like to be able to read the 
audio samples back and maybe do an fft on them.  I know xmms has its own 
APIs, but I wanted to have a generic, one-size-fits-all (sort of) way of 
obtaining the audio samples through ALSA so I could have a generic 
visual client for my whole system.  Is this possible?  And if arecord 
happens to be able to do this, how might I do it?  If there are already 
programs that do this (using the ALSA API), that would be very useful as 
well.

TIA,
Ron