Colorspace YUV/RGB problem / GPU's RGB Full range setup?

Help & Support Hardware
6

Hello,
yes, I tried to explanatory as much as posible :slight_smile:

Important parts are:

  • By default, Odroid C2 seems to use YUV444 Colourspace (by design?). The projector automatically doesnt recognize correct Color range (limit/full). I can set up correct level manually, just the Automatic option on projector choose wrong range. TV shows picture “fine” (not dark, not washed), but for some reason TV settings Full/Limited video range doesnt make any difference. I would like to use RGB - RGB video range is correctly detected both Projector and TV, and I can see TV settings Full/Limited makes actually changes, when switched, as it should.

  • When talking about calibration of colours, there is always question of correctly setup of video range in chain Kodi - GPU - Display. I am not sure, if I can affect anyhow Kodi range (its for another discussion), and I think its Full on Odroid C2 CoreELEC ( color space transformation from Y’CbCr to RGB and the video levels are expanded from 16-235 to 0-255 – WtW & BtB are clipped in the process)

I am trying to setup best possible outcome. And from the 3 correct levels options, regarding GPU, the best should be use Full range.

Kodi-GPU-Display

  1. Full-Full-Full – Both Desktop & Video Content will look correct but video content is also scaled during the Y’CbCr –> RGB color space transformation. BtB & WtW are clipped so calibration will be more difficult
  2. Full-Limited-Limited – This should be avoided since there are two levels of scaling which will likely cause unnecessary banding.
  3. Limited-Full-Limited – Best option for embedded video player as there is zero video content scaling during the Y’CbCr –> RGB color space transformation. BtB & WtW are preserved to make calibration easier. If using a Desktop it will look overly dark

So far, I can see that Odroid GPU shows limited color range whatever colorspace, if I understand this correctly

[ 4721.323102@0] hdmitx: video: Bit depth: 8-bit, Colour range RGB: limited, YCC: limited, Colourspace: YUV444
[ 4812.197755@3] hdmitx: video: Bit depth: 10-bit, Colour range RGB: limited, YCC: limited, Colourspace: RGB

And I try to find the way, how I could change it.
I cant test xrandr --set "Broadcast RGB" "Full" (linux way) as this is not present in CoreELEC.