1, I saw nullAudio custom properties of the static const AudioObjectPropertySelector kPlugIn_CustomPropertyID = 'PCst'; But I don't know how to use this in a project. 2. What is the difference between PlugIn and Device's custom properties? 3. When I try to customize the PropertySelector for deivce. After adding kAudioObjectPropertyCustomPropertyInfoList NullAudio_HasDeviceProperty method to compile again after restarting coreAudio service, found that virtual devices don't show.

I successfully retrieved strings, arrays, and other data through a custom AudioObjectPropertySelector, but I can only get fixed returns. Whenever I modify it to use dynamic data, it results in an error. Below is my code. case kPlugIn_CustomPropertyID: { *((CFStringRef*)outData) = CFSTR("qin@@@123"); *outDataSize = sizeof(CFStringRef); } break; case kPlugIn_ContainDic: { CFMutableDictionaryRef mutableDic1 = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks); CFDictionarySetValue(mutableDic1, CFSTR("xingming"), CFSTR("qinmu")); *((CFDictionaryRef*)outData) = mutableDic1; *outDataSize = sizeof(CFPropertyListRef); // *((CFPropertyListRef*)outData) = mutableDic; } break; case kPlugIn_ContainArray: { CFMutableArrayRef mutableArray = CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks); CFArrayAppendValue(mutableArray, CFSTR("Hello")); CFArrayAppendValue(mutableArray, CFSTR("World")); *((CFArrayRef*)outData) = mutableArray; *outDataSize = sizeof(CFArrayRef); } break; These are fixed returns, and there are no issues when I retrieve the data. When I change the return data in kPlugIn_ContainDic to the following, the first time I restart the CoreAudio service and retrieve the data, it works fine. However, when I attempt to retrieve it again, it results in an error: case kPlugIn_ContainDic: { *outDataSize = sizeof(CFPropertyListRef); *((CFPropertyListRef*)outData) = mutableDic; } break; error code： HALC_ShellDevice::CreateIOContextDescription: failed to get a description from the server HAL_HardwarePlugIn_ObjectGetPropertyData: no object HALPlugIn::ObjectGetPropertyData: got an error from the plug-in routine, Error: 560947818 (!obj) The declaration and usage of mutableDic are as follows: static CFMutableDictionaryRef mutableDic; static OSStatus BlackHole_Initialize(AudioServerPlugInDriverRef inDriver, AudioServerPlugInHostRef inHost) { OSStatus theAnswer = 0; gPlugIn_Host = inHost; if (mutableDic == NULL){ mutableDic = CFDictionaryCreateMutable(kCFAllocatorDefault, 100, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks); } } static OSStatus BlackHole_AddDeviceClient(AudioServerPlugInDriverRef inDriver, AudioObjectID inDeviceObjectID, const AudioServerPlugInClientInfo* inClientInfo) { CFStringRef string = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("%u"), inClientInfo->mClientID); CFMutableDictionaryRef dic = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks); CFDictionarySetValue(dic, CFSTR("clientID"), string); CFDictionarySetValue(dic, CFSTR("bundleID"), inClientInfo->mBundleID); CFDictionarySetValue(mutableDic, string, dic); } Can someone tell me why

I have a 4-input, 4-output hardware device and an 8-input, 8-output virtual device, which I combine into an aggregate device. I am using the SimplyCoreAudio library to get the channel count. The code is as follows: aggregationDevice!.channels(scope: .input) =>> 12 aggregationDevice!.channels(scope: .output) =>> 12 When the program's MicrophoneMode is set to standard, the channel count is correct. However, when I set the MicrophoneMode to voiceIsolation, the channel count is incorrect: aggregationDevice!.channels(scope: .input) =>> 4 aggregationDevice!.channels(scope: .output) =>> 12 Below is the code for creating the aggregate device： func createAggregateDevice(mainDevice: AudioDevice, secondDevice: AudioDevice?, named name: String, uid: String) -> AudioDevice? { guard let mainDeviceUID = mainDevice.uid else { return nil } var deviceList: [[String: Any]] = [ [ kAudioSubDeviceUIDKey: mainDeviceUID, kAudioSubDeviceDriftCompensationKey:1 ] ] // make sure same device isn't added twice if let secondDeviceUID = secondDevice?.uid, secondDeviceUID != mainDeviceUID { deviceList.append([ kAudioSubDeviceUIDKey: secondDeviceUID, kAudioSubDeviceDriftCompensationKey:1, kAudioSubDeviceInputChannelsKey:8 ]) } let desc: [String: Any] = [ kAudioAggregateDeviceNameKey: name, kAudioAggregateDeviceUIDKey: uid, kAudioAggregateDeviceSubDeviceListKey: deviceList, kAudioAggregateDeviceMainSubDeviceKey: mainDeviceUID, kAudioAggregateDeviceIsPrivateKey:false, ] var deviceID: AudioDeviceID = 0 let error = AudioHardwareCreateAggregateDevice(desc as CFDictionary, &deviceID) guard error == noErr else { return nil } return AudioDevice.lookup(by: deviceID) } I hope someone can tell me the reason Thank you！