ADV7842 CVBS to RGB Out

I've been using the AVES scripts for the ADV7842/AD7511 eval board to successfully setup up my custom ADV7842 board to handle analog RGB inputs.  I've moved onto CVBS (NTSC) inputs and I'm not having the same success.  I started with the 1-1e script (NTSC to 480i HDMI) and I was able to get video out of my board but the colors where all messed up.  Specifically, black is coming out as purple and white is coming out as a lime color.  As I dug into it I saw the script sets up the ADV7511 to accept YCrCb so the ADV7842 must output YCrCb.  However, the DVI Transmitter on my board only accepts RGB so I need the ADV7842 to output RGB as it did with the analog RGB input scripts.  I thought that should be as simple as switching 0x40 (IO) 0x02[1] from '0' to '1' but that seemed to have no impact.  I realize the analog RGB inputs use CP and the CVBS inputs use SDP but other than the register I just mentioned I don't see anything related to SDP color output specifically.

I've been analyzing scripts all day and I can't seem to figure out why the analog RGB input scripts work but the CVBS input scripts don't.  Do you have any ideas or things for me to check that might help me diagnose because I'm pretty stumped?

By the way, I tried disabling the 3D comb filter to take the SDRAM on my board out of the equation and it didn't resolve my issue.

Thanks,

Nathan

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    •  Analog Employees 
    on Jul 22, 2011 8:21 PM over 9 years ago

    Hi Nathan,

    I believe the CSCs we use are pretty much the same on most devices so I'd begin by getting the hardware manual for the ADV7441A at

    http://ez.analog.com/docs/DOC-1546

    and look at Table 36 on page 107.  Select CSC Mode 0001 which is YPbPr 601 to RGB.  These coefficients should work fine for CVBS to RGB conversion.

    You're right, I should be able to do CVBS -> RGB 480p script but it will take a bit of time to write and verify.  I'll need to turn on the line doubler to do the interlace to progressive conversion.

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  • 0
    •  Analog Employees 
    on Jul 22, 2011 8:21 PM over 9 years ago

    Hi Nathan,

    I believe the CSCs we use are pretty much the same on most devices so I'd begin by getting the hardware manual for the ADV7441A at

    http://ez.analog.com/docs/DOC-1546

    and look at Table 36 on page 107.  Select CSC Mode 0001 which is YPbPr 601 to RGB.  These coefficients should work fine for CVBS to RGB conversion.

    You're right, I should be able to do CVBS -> RGB 480p script but it will take a bit of time to write and verify.  I'll need to turn on the line doubler to do the interlace to progressive conversion.

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