[Portaudio] USB Full-duplex for OS X

[Phil Burk]

Hello Ichiro,

Thanks for the mods to support full duplex using TWO CoreAudio devices.

> I modified pa_mac_core.c (4/12/02 version) in portaudio (V18) to get
> full-duplex using USB iMic on pd.

Do you like the iMic? I am thinking of getting one. Then I can test these
mods and also get rid of my PowerBook clicks.

> - Start (and stop) a second IOProc when there are two different CoreAudio
>   devices.  (Even two different physical devices, I can get input from
>   iMic and output on Built-in speakers.)

Your mods were quite small. How do you get the audio from the input Proc to
the output Proc. For the Mac SoundManager implementation, I added a FIFO
between the two PRoc so that I could pass data from the input proc to the
output proc. Then I can call the PA user callback with full buffers for both
input and output.

Phil Burk