Technical Q&A

SND12 - The siOSTypeInput Selectors (12-April-98)

	inputSource = kCDSource;
	err = SPBSetDeviceInfo (soundRefNum, siOSTypeInputSource, &inputSource);
	

or pass a pointer to an OSType to hold the result of a call to SPBGetDeviceInfo, for example:

	OSType		inputSource;
	err = SPBGetDeviceInfo (soundRefNum, siOSTypeInputSource, &inputSource);

The siOSTypeInputAvailable selector works with SPBGetDeviceInfo and returns a SoundInfoList structure, which is a short followed by a Handle, as its result. You can then parse the SoundInfoList to get the number of OSTypes that are in the returned handle.

Here is a simple example of how to walk the returned handle extracting each OSType.

SErr GetSoundInputSourceOSTypes (long siRefNum) {
	OSErr				err;
	SoundInfoList			sourceTypes;
	long				offset			= 0;
	short				numTypes;
	int				i;
	char				sourceType[5];
	Handle				OSTypes			= nil;
         
	err = SPBGetDeviceInfo (siRefNum, siOSTypeInputAvailable, &sourceTypes);
	if (err != noErr) {
		printf ("\nGot error #%d from siOSTypeInputAvailable\n\n", err);
	}
         
	if (err == noErr) {
		printf ("\nThe sound input source OSTypes are:\n");
         
		numTypes = sourceTypes.count;
		OSTypes = sourceTypes.infoHandle;
         
		for (i = 0; i < numTypes; i++) {
			BlockMoveData (&(*OSTypes)[offset], sourceType, 4);
			sourceType[4] = 0;
			printf ("  %s\n", sourceType);
			offset += sizeof (OSType);
		}
	}
         
	if (OSTypes != nil) {
		DisposeHandle (OSTypes);
	}
         
	return err;
}

The input source constants are defined in Universal Headers 3.1 and later. Here are the currently defined constants:

/* input source Types*/

enum {
    kNoSource            = FOUR_CHAR_CODE('none'),   /*no source selection*/
    kCDSource            = FOUR_CHAR_CODE('cd  '),   /*internal CD player input*/
    kExtMicSource        = FOUR_CHAR_CODE('emic'),   /*external mic input*/
    kRCAInSource         = FOUR_CHAR_CODE('irca'),   /*RCA jack input*/
    kTVFMTunerSource     = FOUR_CHAR_CODE('tvfm'),
    kDAVInSource         = FOUR_CHAR_CODE('idav'),   /*DAV analog input*/
    kIntMicSource        = FOUR_CHAR_CODE('imic'),   /*internal mic input*/
    kMediaBaySource      = FOUR_CHAR_CODE('mbay'),   /*media bay input*/
    kModemSource         = FOUR_CHAR_CODE('modm'),   /*modem input*/
    kZoomVideoSource     = FOUR_CHAR_CODE('zvpc')    /*zoom video input*/
};

    siOSTypeInputSource    = FOUR_CHAR_CODE('inpt'),  /*input source by OSType*/
    siOSTypeInputAvailable = FOUR_CHAR_CODE('inav'),  /*list of available input source OSTypes*/