I have an old S905 box, it has two video outputs… With stock firmware, if I switch between the outputs, everything works as it should. Android (albeit an ancient variety) scales down the picture on the second output just fine. I can switch between the outputs with my television remote just fine.
With Coreelec, it doesn’t quite work that way. I have to tell Kodi that there’s a second display output (it’s composite - so I have to add “480cvbs” to the disp_cap file), and then it only works with one of the ourputs connected. If they’re both connected, it flips out.
I did some testing with ancient varieties of coreelec (and one really old libreelec that works with the original dtb.img extracted from the stock android firmware), and they all exhibit this behavior.
So this seems like a longshot, but is there any way to add this functionality to Coreelec?