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ADV7604 and video with one long line

Question asked by CurtJohnson on Nov 8, 2012
Latest reply on Nov 21, 2012 by CurtJohnson

We have been using the AD9888 in a product for many years. This year I changed over to the ADV7604 to get DVI capability.


A major customer has 31kHz, 1023 line interlaced, composite monochrome video with a 1024x940 image. I am using autographics mode, and can successfully capture video from a video generator set to the customer's video specification.

As it turns out, the customer's actual equipment has one line, the first line of the vertical front porch of one field, that is 8 pixels longer than every other line. The AD9888 seems to adapt the the change quickly; I never knew that the anomaly existed until now.


The ADV7604 does not deal with the long line well. For the next 110 lines, the horizontal sync on HS is 8 pixels early, with a changing width. Then I get one line with two horizontal sync pulses 8 pixels apart; and the rest of the frame has horizontal sync in the correct position. What I end up with is an image where 20% of one field is offset.


I tried changing HS_OUT_SEL to output asynchronous Hsync. That works better, but it is still synchronous to LLC, and has a 1 or 2 pixel jitter that makes it impossible to get a stable image.


I see nothing on RAW_SYNC with any setting of SEL_RAW_CS.


ESDP is only available for 480i, 576i, 480p, and 576p, according to the data sheet. I tried enabling it anyway, but was unable to get any HS or VS_FIELD output at all.


Settings are attached.


Does anyone have any suggestions for getting a HSync that is stable? Either the regenerated Hsync that adapts to the long line more quickly, or a true sliced but asynchronous sync that I can use to extract HSync in FPGA. I'm hoping not to have to spin the board to add an external sync slicer just for this one case.



Curt Johnson