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ADV212, Variable frame rate with Custom Video Mode, Sync timing

Question asked by nachumk on Sep 11, 2012
Latest reply on Sep 17, 2012 by DaveD

Hi,

 

I am implementing logic in an FPGA to send frames for encoding to an ADV212 over the VDATA bus. The frames will arrive at the ADV at a variable rate. I can make sure to provide a whole line without a gap, but I expect to vary the HSync time between lines (and of course VSync between frames).

 

1. Can I use Custom Video Mode?

2. Do I need to toggle FIELD? Or can I leave FIELD set as 0. I am not using interlaced video.

3. Can the blanking (HSync) times be variably stretched between lines and frames? Beyond the minimum of 16 and 6 for HSync and VSync?

4. Would this be easier to do if I used SAV/EAV instead of HVF?

5. I am still confused by the timing required by the ADV for HSync and VSync? Is there a clear diagram showing the waveform for the start of a frame, start of a line, end of a line, and end of a frame? The documentation says that HSync and VSync cannot be asserted simultaneously, but does that mean that they cannot both rise at the same time, or be high at the same time? The documentation also says something about "Apply Vsync followed by Hsync after 4 clk cycles" in JDATA mode, but I am in VDATA mode.

 

Thanks you,

Noah

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