ADV7182 creates dark line at bottom with NTSC input when ACE is ON

Hello,

I am facing an issue with ADV7182 chip in NTSC input format where I can see the dark line at the bottom when ACE feature is ON.

This dark line is clearly visible in blue color in free-run mode. The same is visible even in actual NTSC blue color data.

This dark line issue at bottom is seen only with NTSC format when ACE feature is ON.

And the dark line at bottom is not observed with NTSC format when ACE feature is OFF.

I could not see any dependencies in datasheet regarding ACE, Please provide the solution for this issue.

Note: ACE means Adaptive Contrast Enhancement.

  • Hi Suresh,

    Could you please describe your system. Are you using an ADV7182 evaluation board or are do you have the ADV7182 in a system. If it is in a system would you mind telling me what is processing the BT656 output from the ADV7182.

    Would you mind sharing a picture a picture of the black line that occurs on the output from the ADV7182?

    Could you try toggling the BT656-4 bit (User Map, register 0x04 bit [7]). Setting this bit to 1 causes the ADV7182 to output video with the ITU-R BT.656-4 timing instead of the standard ITU-R BT.656-3 timing.

    If the receiver is expecting ITU-R BT.656-4 and ITU-R BT.656-3 is being output from the ADV7182 then this can result in black horizontal lines at the top of bottom of the screen.

    Regards,

    Robert Hinchy

    Applications Engineer,

    Digital Video Products Group,

    Analog Deivces Inc.

  • Hi,

    Thanks for your response.

    I am using ADV7182 in my system. I cannot say it is black line, because the dark line at the bottom is visible clearly in the free-run mode that too in blue color background.

    This is visible only in NTSC format when ACE feature is ON.

    I do not the see the same kind of dark line in PAL type.

    I dont think its problem with ITU-R.BT 656 timing issue.

    I disabled the ACE feature,and the dark line was not visible anymore in NTSC format.

    Note: The dark horizontal line is visible from the left screen to the half of the screen only.

    The position of the dark line occurance is not at the bottom every time. Sometimes it is visible at center position too but most of the time it is visible from the bottom above ~1cm.

  • Hi Suresh,

    Sorry for not getting back to you sooner.

    Could you try writing 0x00 to User Sub map 2, register 0x84 . This should fix the issue.


    regards,

    Robert

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