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ADV7842 - how to shift picture a few pixels down

Category: Hardware
Product Number: ADV7842


I'm capturing the video from the LD player and the picture is a little bit shifted to the top and to the right that results in cutting a few pixels on the top and right edges. I would like to shift it down and to the left. What is the registry command to do that? Thanks.

PS. This issue is the same as thisRE: ADV7842 SDP Shift 

Added a link to the related issue.
[edited by: metaleonid at 1:57 AM (GMT -4) on 3 Apr 2023]
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  • Hi Poornima,

    I tried the script that you provided with the default settings but it didn't fix the issue at all. In fact the image is even further shifted to the right. Here're the screenshots. Can you please provide the solution / workaround how to shift the image back (in this case to the left and down). Thank you.

    PS. The S-Video image is horrible (the second one). For some reason the board produces the "net" artifacts. I don't have to use S-Video but just letting you know.

  • Hi Poornima,

    I just tried the capturing from the DVD player 1st outputting directly HDMI into my capture device. And in the 2nd capture I was using composite-in into ADV7842 board and then HDMI out to my capture device. As you see the image from the direct capture - it is not shifted. But using ADV7842 it is shifted to the top-right. I would like to play with the register settings for horizontal and vertical shift. But can you confirm if I correctly got it at the bottom of this message?

    Directly from DVD - not shifted.

    Composite into ADV7842 - shifted to the top-right

    Regarding the shift. If I want to shift 96 pixels to the left, I need to subtract 96 from 1024, right?

    1024 - 96 = 928 = 0x3A0

    44 8B 43; de_h_end shifted by -96 pixels

    44 8C A0; de_h_end shifted by -96 pixels

    Is this how it is computed?

    0x3A0 = 11 1010 0000

    0xA0 shall go to both 44 8C (d_h_end) and 44 8D (d_h_start)

    And the number 0x3 = 11 shall go to register 44 8B. 

    My understanding is that register 44 8B has two right-most bits for de_h_end [1:0] and bits 3rd and 4th are for d_h_start [3:2].

    Thus putting 0x3 in in [1:0] and then in [3:2] is same as putting 0xF into 44 4B [3:0]

    Is this right?

    Anyhow, the writing to these registers does not shift the image. Is there anything else? The progressive footage does not suffer from this problem. The image is not shifted. Only interlaced. But my sources are interlaced.