I am having a problem getting the colors right with a 4K YCbCr input on my target system (3840x2160 30Hz, probably happens at lower frame rates too). I'm working with 4:4:4, but I see it with 4:2:2 also. I have YCbCr inputs working at any lower resolution, 1080p60 for example -- the colors appear correct. I use the same settings to the 2 registers that are involved for color space conversion: IO (0x98): 02, and CP (0x44): 6C. For the working 1080p60 case I set 0x98:02 = 0xF2, and 0x44:6C = 80. Using these same settings for the 4K input, I expect correct colors, but instead the image appears with distorted colors:
Here is the image when it is 4K rgb (1080p60 rgb or ycbcr will also look like this), correctly displayed:
Do any color space registers need to be set differently for 4K YCbCr vs 2K YCbCr? As mentioned above I already have lower resolutions working for YCbCr, so it is not a generic YCbCr handling problem, it is only a problem for 4K. And 4K RGB works fine -- we have that worked out. I've confirmed that our scaler downstream is not converting the color space. The source used for this test (above pictures) was Quantum 804A, but we've seen this with other 4K sources. I've confirmed with the 7619 reg HDMI (0x68):53 that the Rx infoframe shows BT709. Trying to force the image to BT709 in reg 0x98:02 also doesn't work: I see no effect on the image.
Any help would be appreciated,