Okay, let’s do it as per specification!
Dude, Rockchip 3399 has HDMI 2.0 video out. On Amlogic A311D, HDMI 2.1 video output, respectively, the range is wider on Amlogic, let’s think logically 
HDMI 2.0 and 2.1 just have very slight differences, but of course a difference, is a difference…
Let me see if the A311D spec sheet has something to say…
The fact is at least that it is not worse than on Rockchip, and as for the processor, soc must fully support the version of HDMI with which it is paired, otherwise it is pointless.