Retrieval audio devices of yours with CoreAudio HAL.

devices.c

// $ clang -framework CoreAudio devices.c

#include <stdio.h>
#include <stdlib.h>
#include <CoreAudio/CoreAudio.h>


int main(int argc, char *argv[]) {
    
    AudioObjectPropertyAddress theAddress = { kAudioHardwarePropertyDevices,
                                                  kAudioObjectPropertyScopeGlobal,
                                                  kAudioObjectPropertyElementMaster };
          
          
          
    UInt32 theDataSize = 0;
    OSStatus err;
    err = AudioObjectGetPropertyDataSize(kAudioObjectSystemObject, &theAddress, 0, NULL, &theDataSize);                       
    if (err != noErr) {
        return -1;
    }
                   
    printf("the data size is %d bytes.\n", theDataSize);
    
    
    UInt32 numOfDevices = theDataSize / (UInt32)sizeof(AudioDeviceID);
    
    printf("device count is %d.\n", numOfDevices);
    
    AudioDeviceID* deviceIDs = malloc(theDataSize);
    memset(deviceIDs, 0, theDataSize);
    
    err = AudioObjectGetPropertyData(kAudioObjectSystemObject, &theAddress, 0, NULL, &theDataSize, (void *)deviceIDs);
    if (err != noErr) {
        printf("could not get devices %d\n", err);
        return -1;
    }
    
    for(size_t i = 0; i < numOfDevices; i++) {
        printf("device %ld is %u.\n", i, deviceIDs[i]);
    }
    
    free(deviceIDs);

    return 0;
}