When you connect an external display via USB-C to an iPad, that displays shows in iPadOS via Settings -> Display and Brightness -> Name of Display.
There is an option called 'Allow Display Mode Changes' for an external display which is described as follows:
When this is on, the display mode will change to match the dynamic range and frame rate of the content you're viewing. This may result in flickering or long periods of black whenever content changes.
Does anyone know how this functionality works and how to support it for an iPadOS App?
In my tests the iPad always outputs at a frame rate of 60fps or sometimes 59.94fps. If the video I am playing back from an AVPlayer is at 25fps the external display stays at 60fps both with 'Allow Display Mode Changes' toggled on/off. Given that it's meant to 'match frame rate of content' I would expect the external display to change from 60fps -> 25fps.
I can not find any documentation about this feature and what AV Frameworks it talks to or gets it's frame rate information from. If anyone has any idea or has experimented with it and learnt something that would be much appreciated.