[PD] Trouble enabling full-duplex audio using ALSA

[Lewis Pike]

I'm having difficulty enabling simultaneous audio input and output
(full-duplex) under pd.

I can get output to work and I can get input to work but I can't seem
to enable both at the same time.  Whenever I try, pd gives an error
message stating "audio I/O stuck... closing audio."

I am running linux 3.6.6 with an M-Audio Fast Track Pro usb sound
card.  The pd version is 0.43.4 and I have configured it to use the
ALSA audio API.

As a test, I've managed to get both audio capture and playback running
simultaneously outside of pd by running the following command:

arecord -f dat -D hw:0,1 | aplay -f dat

These above command successfully pipes audio in to audio out, so I can
confirm that full-duplex should be possible with my current hardware.

Can anyone provide some insight?

-Lewis