how to get Audio Device UID to pass into NSSound's setPlaybackDeviceIdentifier:

Question

Hi All,

How can i get audio device UID (USB speaker) to pass into NSSound's setPlaybackDeviceIdentifier: method

Thanks

Answer 1

ok i got it myself...

the theCFString will contain the device UID

UInt32          theSize;
char            theString[kMaxStringSize];
UInt32          theNumberDevices;
AudioDeviceID   *theDeviceList = NULL;
UInt32          theDeviceIndex;
CFStringRef     theCFString     = NULL;
OSStatus        theStatus = noErr;

// this is our driver
const char      *nameString = "Burr-Brown Japan PCM2702";
const char      *manufacturerString = "Burr-Brown Japan";



// device list size
theSize = 0;
theStatus = AudioHardwareGetPropertyInfo(kAudioHardwarePropertyDevices, &theSize, NULL);


theNumberDevices = theSize / sizeof(AudioDeviceID);

// allocate the device list
theDeviceList = (AudioDeviceID*)malloc(theNumberDevices * sizeof(AudioDeviceID));

// get the device list
theSize = theNumberDevices * sizeof(AudioDeviceID);
theStatus = AudioHardwareGetProperty(kAudioHardwarePropertyDevices, &theSize, theDeviceList);

// iterate through the device list, find our device and return the UID
for(theDeviceIndex = 0; theDeviceIndex < theNumberDevices; ++theDeviceIndex)
{
    // get name
    theSize = kMaxStringSize;
    theStatus = AudioDeviceGetProperty(theDeviceList[theDeviceIndex],
                                       0, 0, kAudioDevicePropertyDeviceName, &theSize, theString);

    NSLog(@"%s",theString);


    // is it me?
    if (strncmp(theString, nameString, strlen(nameString)) == 0) {

        // get manufacturer
        theSize = kMaxStringSize;
        theStatus = AudioDeviceGetProperty(theDeviceList[theDeviceIndex], 0, 0,
                                           kAudioDevicePropertyDeviceManufacturer, &theSize, theString);

        NSLog(@"%s",theString);
        // is it really me?
        if (strncmp(theString, manufacturerString, strlen(manufacturerString)) == 0) {
            // get device UID
            theSize = sizeof(CFStringRef);
            theStatus = AudioDeviceGetProperty(theDeviceList[theDeviceIndex],
                                               0, 0, kAudioDevicePropertyDeviceUID, &theSize, &theCFString);
            NSLog(@"%s",theCFString);



            break;
        }
    }
}

Answer 2

AudioHardwareGetProperty is deprecated in snow leopard.

Answer 3

To avoid the deprecated AudioHardwareGetProperty and AudioDeviceGetProperty calls replace them with something like this:

AudioObjectPropertyAddress  propertyAddress;
AudioObjectID               *deviceIDs;
UInt32                      propertySize;
NSInteger                   numDevices;

propertyAddress.mSelector = kAudioHardwarePropertyDevices;
propertyAddress.mScope = kAudioObjectPropertyScopeGlobal;
propertyAddress.mElement = kAudioObjectPropertyElementMaster;
if (AudioObjectGetPropertyDataSize(kAudioObjectSystemObject, &propertyAddress, 0, NULL, &propertySize) == noErr) {
    numDevices = propertySize / sizeof(AudioDeviceID);
    deviceIDs = (AudioDeviceID *)calloc(numDevices, sizeof(AudioDeviceID));

    if (AudioObjectGetPropertyData(kAudioObjectSystemObject, &propertyAddress, 0, NULL, &propertySize, deviceIDs) == noErr) {
        AudioObjectPropertyAddress      deviceAddress;
        char                            deviceName[64];
        char                            manufacturerName[64];

        for (NSInteger idx=0; idx<numDevices; idx++) {
            propertySize = sizeof(deviceName);
            deviceAddress.mSelector = kAudioDevicePropertyDeviceName;
            deviceAddress.mScope = kAudioObjectPropertyScopeGlobal;
            deviceAddress.mElement = kAudioObjectPropertyElementMaster;
            if (AudioObjectGetPropertyData(deviceIDs[idx], &deviceAddress, 0, NULL, &propertySize, deviceName) == noErr) {
                propertySize = sizeof(manufacturerName);
                deviceAddress.mSelector = kAudioDevicePropertyDeviceManufacturer;
                deviceAddress.mScope = kAudioObjectPropertyScopeGlobal;
                deviceAddress.mElement = kAudioObjectPropertyElementMaster;
                if (AudioObjectGetPropertyData(deviceIDs[idx], &deviceAddress, 0, NULL, &propertySize, manufacturerName) == noErr) {
                    CFStringRef     uidString;

                    propertySize = sizeof(uidString);
                    deviceAddress.mSelector = kAudioDevicePropertyDeviceUID;
                    deviceAddress.mScope = kAudioObjectPropertyScopeGlobal;
                    deviceAddress.mElement = kAudioObjectPropertyElementMaster;
                    if (AudioObjectGetPropertyData(deviceIDs[idx], &deviceAddress, 0, NULL, &propertySize, &uidString) == noErr) {
                        NSLog(@"device %s by %s id %@", deviceName, manufacturerName, uidString);

                        CFRelease(uidString);
                    }
                }
            }
        }
    }

    free(deviceIDs);
}