For HEVC I finally got around the issue by carefully collecting NALUs that are just slice segments which belong to the same frame (checking first_slice_segment_in_pic_flag) before handing them over to VTDecompressionSessionDecodeFrame() in one batch.

Those 300kB were with 4 Mbps / 2 fps setting. With 25 fps setting I get ~120 kB type-19 and ~5-11 kB type-1 NALUs, but ALL of them produce the -12909 error.

What is UserData()?

How can we then reduce address space usage in Swift?

The current iOS 15.4 beta did solve the issue for me

Thanks! In this case I should definitely try the 15.4 beta…

Thanks for posting the responses from Apple. The thing is, I‘m having those issues with the app running in the foreground and with the debugger attached. A situation where no throttling should be applied according to Apple.

On which iOS version does it still work for you? For me the background notifications stopped working with iOS 15.3.

When calling installTap(...) on the inputNode of AVAudioEngine may I set the format parameter to nil or do I need to explicitly set it to the outputFormat(forBus:) of the inputNode?