Are you sure abour this? Because wikipedia says the SOC is able to handle this. And I can also confirm this twice:
First the Libreelec build for tinkerboard works like a charm and is able to play 4k-10Bit video files with a low CPU load.
And second i just tested the Rockchip player from your script and its also able to decode the files but only for a few seconds. But CPU load in this time is low.
I have to thank you for your work, the 10-Bit thing is just a tiny one and all other things are working perfect for me.