Amlogic codecs not used in Live TV

Hi,
just got one of the S912 , Beelink GT1 and have some issues.
Most/all of the videos plays OK and for that purpose Kodi is OK. Pressing O i can see that amc-H26X codecs are used.
However i use my box mostly for Live TV via Tvheadend server and here i have issues. Kodi is using ff-h264 and ff-mpeg2 codecs instead of amc codecs which results in software decoding instead of hardware. Live TV is very choppy on this GT1 box.

How can i tweak Kodi to use amc codecs even for Live TV, why is this not by default?
I have another S905 box and Kodi is working well on that one with amc codecs in Live TV also.