Hello,
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.
Hi,
Could you please try with reference script which is available at ADV7842 Design Support Files - Documents - Video - EngineerZone (analog.com) & from the default reference configuration you may not get such pixel shift .
Also try with some other sources instead of LD player.
The position of the signal can be controlled be using below register and kindly configure these registers accordingly, For more details, Please refer section "OUTPUT SYNCHRONIZATION SIGNAL POSITIONING" at UG-214: ADV7842 Hardware User Guide
How should we set START_VS and END_VS ?
The picture gets shifted by a number of clocks equal to the hsync width. For example, the hsync width is 40 clock cycles for 720p, so the picture would get shifted by 40 pixel clocks.
If you look at the CEA-861 specification, you will see that the 640x480p @ 59.94/60Hz has an hsync width of 96 clock cycles.
The DE sync leading and trailing edges must therefore be shifted by 96 pixels towards the left, i.e.:
• de_h_start[9:0] = 0x3A0 (-96 pixels of shift)
• de_h_end[9:0] = 0x3A0 (-96 pixels of shift)
This results in the following settings (the sequence of the writes is important and must be followed):
44 8B 43; de_h_end shifted by -96 pixels
44 8C A0; de_h_end shifted by -96 pixels
44 8B 4F; de_h_start shifted by -96 pixels
44 8D A0; de_h_start shifted by -96 pixels
Thanks,
Poornima
Hi Poornima,
Unfortunately, this series didn't do anything. I expected to shift the image, but it did't. I'd like to ask you how you arrived to the numbers. x3A0 is 1110100000 in binary which is 928 in decimal. What is the connection between 928 and -96? I'd like to play with it and try different numbers.
I'm attaching the screenshot of the video capture. Take a look how image is shifted to the right and to the top. All I need to do is to shift it back. Thank you.
