[PD] USB Full-duplex for OS X

[ich at peabody.jhu.edu]

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

Although one can get full-duplex using Built-in audio because it appears
as one CoreAudio device, iMic, for example, is mapped to two CoreAudio 
devices.

Main modifications:
- 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.)

- In the IOProc (actually Pa_TimeSlice) use mNumberBuffers instead of
  past_NumOutputChannels to determine if this is for output or input.

Note: it's tested only with iMic and pd-0.35-test23 (G4 laptop).

The diff file is provided below (patch pa_mac_core.c diff).

Ich

=================================================
Ichiro Fujinaga (ich at jhu.edu)
Computer Music Department
Peabody Institute of the Johns Hopkins University
1 E. Mount Vernon Place, Baltimore MD USA 21202
Voice: (410) 659-8100 x1240 Fax: (410) 783-8592
http://www.peabody.jhu.edu/~ich
=================================================

656c656,657
<     if( past->past_NumOutputChannels > 0 )
---
> //    if( past->past_NumOutputChannels > 0 )  IF
>     if( outOutputData->mNumberBuffers > 0 )
662c663,664
<     if(  past->past_NumInputChannels > 0  )
---
> //    if(  past->past_NumInputChannels > 0  ) IF
>     if( inInputData->mNumberBuffers > 0 )
668a671
> 
712c715
< // printf("Num input Buffers: %d; Num output Buffers: %d.\n", inInputData->mNumberBuffers,	outOutputData->mNumberBuffers);
---
> //printf("Num input Buffers: %d; Num output Buffers: %d.\n", inInputData->mNumberBuffers, 	outOutputData->mNumberBuffers);
974a978
> #if 0 // checking diabled IF
987c991
< 
---
> #endif
1050a1055,1070
> 
> // IF start - code added
>     if (pahsc->pahsc_AudioDeviceID != sDeviceInfos[past->past_OutputDeviceID].audioDeviceID)
>     {   
>         AudioDeviceID outputDeviceID = sDeviceInfos[past->past_OutputDeviceID].audioDeviceID;
>         // Assumes output device since pahsc->pahsc_AudioDeviceID is set as inputdevice last in PaHost_OpenStream()
> 
>         // Associate an IO proc with the device and pass a pointer to the audio data context
>         err = AudioDeviceAddIOProc(outputDeviceID, (AudioDeviceIOProc)appIOProc, past);
>         if (err != noErr) goto error;
>     
>         // start playing sound through the device
>         err = AudioDeviceStart(outputDeviceID, (AudioDeviceIOProc)appIOProc);
>         if (err != noErr) goto error;
>     }
> // IF end    
1085a1106,1115
>     if (pahsc->pahsc_AudioDeviceID != sDeviceInfos[past->past_OutputDeviceID].audioDeviceID)
>     {   // stop if second IOProc was started IF
>         AudioDeviceID outputDeviceID = sDeviceInfos[past->past_OutputDeviceID].audioDeviceID;
>         // FIXME - we should ask proc to stop instead of stopping abruptly
>         err = AudioDeviceStop(outputDeviceID, (AudioDeviceIOProc)appIOProc);
>         if (err != noErr) goto Bail;
>     
>         err = AudioDeviceRemoveIOProc(outputDeviceID, (AudioDeviceIOProc)appIOProc);
>         if (err != noErr) goto Bail;
>     }