Fiddling with the h264 and h265 params I found both keyint and min-keyint settings.
Setting keyint shouldn't force the codec library to use exactly that frame interval?
Do min-keyint have something to do with scene detection and if set it take priority over keyint plain setting ?
TL;DR: I found that h265 default settings are keyint=250 and min-keyint=25 ... what I should expect from that? A fixed length GOP or a variable length one?