Dear Sirs, I've written an audio driver based on IOUserAudioDevice. In my IOOperationHandler I can receive and send the audio samples as expected. Is there any way to configure the number of samples transferred in each call? Currently it seem to be around 512 samples per call, which relates to 10.7 millisecs when operating on 48 kHz samplerate. I'd like to achieve something like 48 or 96 samples per call. I did some experiments and tried calls to SetOutputLatency() etc. but so far I didn't find the right way to change the in_io_buffer_frame_size in the callback. I'd like to do this as smaller buffer sizes would allow lower latencies for the subsequent audio processing. Thanks and best regards, Johannes

Hello, now I need to make a control software for a multi-channel sound card device. The Mixing is implemented on the system through ASIO driver on the Windows side. Let's say I have an OUTPUT A channel and an OUTPUT B channel. On Windows I can share the audio from channel A to channel B so that I can hear it on channel B as well, even though I chose channel A as the playback channel. Now I need to implement this function on the mac, but I have not contacted the development of this aspect before, so I would like to ask whether Core Audio or driver can implement this function

Dear Sirs, when writing an AudioServerPlugin I can use the hosts WriteToStorage/CopyFromStorage functions to save and restore custom properties on restarting the machine. Are there corresponding functions for an audio driver based on AudioDriverKit? What would be the recommended way to save and restore properties so that they are available again after a reboot in an audio driver based on AudioDriverKit? Thanks and best regards, Johannes

Dear Sirs, I've written an audio driver based on AudioDriverKit. In my audio callback function I'm receiving calls with io operation IOUserAudioIOOperationWriteEnd and IOUserAudioIOOperationBeginRead as expected which means I see IOUserAudioIOOperationWriteEnd operations during a playback in an application like VLC or the browser and I see IOUserAudioIOOperationBeginRead when recording in Audacity etc.. But when I open the SystemSettings and goto Sound and I select my driver as input I also see calls with IOUserAudioIOOperationWriteEnd which seem to be the just read input data. I can also watch this when starting up Teams. I think the purpose is to add the (mic) input also to the output so you have the chance to listen to yourself. Nevertheless I'd like to fully avoid this but I don't see a way to distinguish between the playback audio data and the input audio data inside this callback. How could I do this? Or even better is there a switch which would completely switch off these callbacks which forward the input to the output? Thanks and best regards, Johannes

Hi, I have an idea for an audio application. It does make use of HRTFs in a different way. So I would like to get the HRTF that was made for the user and use it in the application. Is that possible?

Dear Sirs, I've written a Swift App, a C++ application and a Driver Extension using DriverKit and AudioDriverKit. As it works on my development machine now I'd like to give it to some other users and so I'm trying to make a Release Build. I've created a Signing Certificate for "Apple Distribution" which I can use for my Swift App and the C++ application which also both use "com.apple.developer.driverkit.userclient-access". I've been given this entitlement and the "Distribution Support" is for "Development, Ad hoc, App Store, Developer ID". For my Driver Extension I'm using the entitlements "com.apple.developer.driverkit" and "com.apple.developer.driverkit.family.audio" which I've also been given and which show the identical "Distribution Support". But when I try to use my Signing Certificate XCode refuses to use the provisioning profile for the Dext and says "Xcode 14 and later requires a DriverKit development profile enabled for iOS and macOS. Visit the developer website to create or download a DriverKit profile." On the other hand I have to use the same Signing Certificate for my Swift App that embeds the Dext and the Dext itself. How can I create a Signing Certificate for Release mode that works for both, the Swift App and the Dext? Thanks and best regards, Johannes

Dear Sirs, I'd like to add an icon to my audio driver based on AudioDriverKit. This icon should show up left of my audio device in the audio devices dialog. For an Audio Server Plugin I managed to do this using the property kAudioDevicePropertyIcon and CFBundleCopyResourceURL(...) but how would you do this with AudioDriverKit? Should I use IOUserAudioCustomProperty or IOUserAudioControl and how would I refer to the Bundle? Is there an example available somewhere? Thanks and best regards, Johannes

Dear Sirs, I’d like to write a virtual audio driver that also exchanges data with a application and thus probably also offers a driver extension using IOUserClient. My first implementation was based on the sample https://developer.apple.com/documentation/audiodriverkit/creating_an_audio_device_driver and everything works fine and as expected on my development machine and I can install/uninstall the dext from within my application. But I had to learn that I will not be given the required entitlement com.apple.developer.driverkit.family.audio as AudioDriverKit seems to be not intended to be used for virtual drivers. So I found out that this sample should be used as starting point for virtual audio drivers: https://developer.apple.com/documentation/coreaudio/creating_an_audio_server_driver_plug-in. But this sample does not include a dext offering the IOUserClient interface which I think I need. The next sample I found was https://developer.apple.com/documentation/coreaudio/building_an_audio_server_plug-in_and_driver_extension . This doesn’t use AudioDriverKit and it includes IOUserClient so it seems to be a good start. Nevertheless it also requires some entitlements which are com.apple.developer.driverkit and com.apple.developer.driverkit.transport.usb. The client also probably needs the entitlement com.apple.developer.driverkit.userclient-access. Would I be given these entitlements for a pure virtual audio driver and why would I need com.apple.developer.driverkit.transport.usb? And is there a chance that AudioDriverKit will also be opened for virtual drivers as it seems to be a much more modern approach and doesn’t require a reboot for installing? Thanks and best regards, Johannes

Hello, I am trying to run a sample project from Apple's Developer Documentation that creates and interfaces with a DriverKit Dext. The project can be found here: Creating an Audio Device Driver. I have followed all the steps in the README.md file: downloading the code, enabling automatic signing, building the app, moving it to the Applications folder, and launching it. I then open the app, press "Install Dext", enable it through System Preferences, and receive the message "SoundboardDriver has been activated and is ready to use." However, the audio device does not appear in the MIDI app, there is no mention of it in the IORegistry, and I get the message “Driver extension is not running” when I try to press "Open User Client". Is there another step I need to follow to get the app running? Perhaps it's an entitlement issue? I don't see any error/fault message in the console app relating to the app or driver. I am running MacOS 13.4.1 (22F82) and Xcode 14.3.1 (14E300c). I have tried with and without SIP enabled, but the issue persists. Any help or guidance would be greatly appreciated. Best, Henry