As far as I see all the actual limitations are just regarding the UE4 editor UI with the “populated available options” under each AJA settings. Maybe it lists all what is need with the certified cards, but it seems like with the other ones you have to trick the editor a bit…
Let me explain, using AJA Kona Lhe+ I only found 1080i50 under the Input Port settings under the AJA plugin settings. From there I simply copied this option (selecting first, and then right button on the selected value and copy). This gives you the correct “syntax” for that particular video format in the port1, so from there it’s very easy to just paste this value (copied text in a notepad) in the proper AJA media output settings. And also in the plugin settings itself. The string you need to paste is this one:
(DeviceIndex=0,ModeName=“1080i 50.00”,FrameRate=(Numerator=25,Denominator=1),TargetSize=(X=1920,Y=1080),VideoFormatIndex=1)
You may need also to change the Play In Editor settings just to match this 1920x1080 resolution. With all that done I’ve been able to see same fill and key working as expected with my monitor showing 1080/50i.
Please note that as far as I know the fields for this interlaced frames are not exactly properly generated but unreal instead is just throwing 50p and letting AJA think that indeed is interlaced. I don’t know if I’m wrong with this last comment…