Brightness / contrast problem

hi, If to compare results with amlogic codec enabled and disabled,
it turns out that when it’s enabled, quality is worse, If to reduce brightness, then saturation information significantly losing compared to sw decoding.
is there a way to fix it somehow pls?

the reason why I’m asking about it is not just to have brightness/contrast controls, using them it’s possible to change video levels and obtain “look of” Full hdmi range output, there’s no such option in CE, I have a couple devices that requires full range, and to be honest, looking for a long of time how to get it in CE. Currently it’s possible only with SW decoding, with HW saturation is losing