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VIP, CVI, BT656 on Seperate Buses

Honored Contributor II

I have an existing (working) design that brings HD-SDI video in and feeds it to a VIP/SOPC chain hitting CVI first. I am using the embedded timing information. This video is two ten-bit buses: Y and C. We've been asked to now add SD-SDI video as an input option. Our SDI decoder on the front end puts out the data as two ten bit buses for SD (at half the clock rate) as well as in HD. So the format is not exactly BT656, it is more like BT1120 as far as video. I did have to regenerate the TRS information as it was multiplexed between the two buses. This would seem to make my life easier but I have not been able to get the chain to work. The output is the same whether I have an SD-SDI signal connected or disconnected. 


My question is does anyone know if the CVI will/should recognize video with embedded timing other than the standard HD-SDI formats? The only difference should be the timing of the EAV/SAV will not match an HD-SDI standard but the CVI shouldn't care about that - should it? 


I see there is a "vid_hd_sdn" signal on CVI for switching between HD and SD but if I don't have to change the existing code that would be preferred. Plus I'll have to do some tricks with my clocking. Any thoughts?
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Honored Contributor II

So I looked at the Avalon Streaming Interface out of the CVI and it recognizes the SD video at 20 bits just fine. Then I remembered about the 525i/480i video having different numbers of lines in each field and how the reference designs have a Clipper up front to clip this. Up until now I had only put 1080i through so I didn't have this problem. So I ran 625i/576i into the VIP chain and this worked just fine. So I think that's the problem.