I've connected an ADV7610 to a 720p video source. It is sending out a very nice YCbCr 16 bit stream to a processor, that is being captured relatively well. Video is fine, it's just shifted to the bottom of 20 pixels. Those 20 pixels are the vertical blanking period: the processor receiving the YCbCr input is ignoring the low data enable pin (that is working correctly), so data is saved starting from the blanking period (that I checked with a scope is indeed 20 lines).
I've tried to change the START_VS register, that allows for a reduction in the vertical blanking period, but I cannot reduce it to zero since that the adjustment is limited to +- 7 pixels.
Is there any other way to reduce or eliminate the vertical blanking period?