[PD] USB Full-duplex for OS X

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@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;
}