I realize that this has been raised in one form or another a number of times (here and here for example), but I would like to get info on this in a more systematic way.
I have a setup consisting of C2 and VU7 Plus. I've tried running both the latest Ubuntu and Android images and with both I get a video output that from what I can see is similar to 16 bit color per pixel. I have tested the VU7 Plus display on its own with another video source (desktop PC with AMD GPU) and it seems to work a lot better, displaying smoother gradients and color range. At the same time the C2 connected to external monitor performs in the same way and shows limited color range.
I have tried to override the color settings using the system tools of the OSes as well as editing U-Boot's boot.ini. The variables I've tried to pass there In one form or another are:
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setenv vout_mode "hdmi"/"dvi"
setenv video_mode "hdmi"/"dvi"
setenv video_bpp "32"
setenv m_bpp "32"
setenv hdmihotplug "1"
setenv hdmioutput "1"
setenv vpu "1"
setenv display_autodetect "true"/"false"
setenv hdmi_forcergb "1"/"0"
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Auto Detect OK:custombuilt,dvi(1024,600,32000,27777,43,1024,1064,1112,1152,600,613,616,645,0,0,1)
- Amlogic force 16 bit color by default to enable/lower the computational cost of 4K video mode
- they leave their firmware to select the bit depth/signal range based on current video content being shown
So, before I throw myself in building my custom U-Boot/OS builds, can anyone confirm, deny or add any info to the above? I'll be very grateful to anyone who could.