ADV7612 problems with HDMI YCbCr 4:2:2 input

I'm using the AD7612 HDMI receiver. All is working fine except when I use a YCbCr 4:2:2 HDMI input. I have no problems with RGB 4:4:4 and YCbCr 4:4:4. The problem is that the colors in 4:2:2 are changed using a simple bar pattern as video input. The white is changed to yellow, the yellow to light green, ...

Is there any limitation in this IC to work with a YCbCr 4:2:2 input ?.

My output is YCbCr 4:2:2 to the BT.656 bus. I tried to change most of the registers related to color space, kind of input but without success.

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    •  Analog Employees 
    on Jun 20, 2017 4:48 PM

    20-bit RGB does not make sense.  RGB 444 should be 24-bits.  For OP_FORMAT_SEL = 0x40 the output is as shown in table 6.  Each color plane has 8 bits.  For BT.656 422 you should be using OP_FORMAT_SEL = 0x80 where Y overlays the green channel and CbCr overlays the blue channel.

    The incoming HDMI can be either RGB 444 or YCbCr 444/422.  It converts the it to 444 internally for processing then converts it again to the output format, either 444 or 422

    Is you input always RGB 444 and you are using the output to convert it to the color space and format you want?

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  • 0
    •  Analog Employees 
    on Jun 20, 2017 4:48 PM

    20-bit RGB does not make sense.  RGB 444 should be 24-bits.  For OP_FORMAT_SEL = 0x40 the output is as shown in table 6.  Each color plane has 8 bits.  For BT.656 422 you should be using OP_FORMAT_SEL = 0x80 where Y overlays the green channel and CbCr overlays the blue channel.

    The incoming HDMI can be either RGB 444 or YCbCr 444/422.  It converts the it to 444 internally for processing then converts it again to the output format, either 444 or 422

    Is you input always RGB 444 and you are using the output to convert it to the color space and format you want?

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