I tried the sample for encoding h265 video stream. I exit with an device could not be initialized. I have an Extreme 4K. Does not every card support h265 encoding?
Just to clarify a potential misunderstanding, H.265 encoding is supported by certain DeckLink devices only, (e.g. the UltraStudio 4k Extreme [1]), and is not supported by the DeckLink 4K Extreme.
H.264 encoding is similarly supported by certain devices only (incl. the H.264 Pro Recorder and ATEM Television Studio).
An application utilising the DeckLink 4K Extreme to perform H.265 (or H.264) encoding would generally integrate code to perform the encoding of the raw video frames provided by the DeckLink API.