I think that macOS 13 has broken this promise. That is, after calling AudioOutputUnitStop from within the I/O proc, the system calls the I/O proc again.

I wanted to add that I could not get the 48MP image until I also set the photoSettings photoQualityPrioritization to the maximum value. Something like this (Objective-C): photoSettings.photoQualityPrioritization = photoOutput.maxPhotoQualityPrioritization;

Thank you for clarifying. I've made a report through Feedback Assistant. This seems like a really poor design decision. You literally cannot use the 48MP capture for time-lapse or stop motion because of this. It is also not documented, and seems counter to the fact that we already have to specify the maximum dimensions... which should be sufficient to trigger this feature.

I'm not sure why the Canon camera isn't being detected, but to get started with actually sending PTP messages, this code is a good start: https://github.com/fruitsamples/PTPPassThrough/tree/master