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DM648 Video Port - Y/C Progressive Capture Question...

JRasmussen
Intellectual 720 points

Hello,

I have been going through the manuals, but I can't find an authoritative answer.  I am feeding a 720p Video Source signal into the DM648's Video Port and I have it set it up for Progressive Scan mode (Capture Field 1 only).  When I am in that mode, are the Field 2 registers (VCXSTART2, VCXSTOP2, VCYSTART2, VCYSTOP2) completely ignored so that a value of 0x0 in those registers doesn't affect anything, or must I put in valid values even though I don't capture Field 2?

There is no possibility that the Video Port is capturing the next Progressive Frame in a Field 2 slot, is there?

What is a full recommended setup for 720p for Video Port capture registers?

Sorry to ask all these questions, but the Data manuals do not explain this very well.....Like everything else, they only explain in detail everything setup for the Field 1 only capture scenario and totally ignore any mention of the Field 2 implications of the device in this mode.  It would be very nice if the manual stated that the Field 2 registers are totally ignored in the Field 1 only Capture mode, if that is truly the case.

Thanks,

  • 0
    TI__Expert 4935 points

    James,

    Field 2 register settings are not used by VPORT when capturing a progressive input like 720p.

    JRasmussen said:

    What is a full recommended setup for 720p for Video Port capture registers?

    How exactly are you connecting the external decoder/FPGA to the VPORT for 720p capture setup?

    Most of the register settings depends very much on this.

  • 0 in reply to Sivaraj R3681
    Intellectual 720 points

    Thanks for the response.  The FPGA is hooked into our VCLKIN1 channel and the H-blank/V-blank signals are tied into a single line to the Video port.

     

    I've tweaked the parameters and 720p is running correctly now for us.  Now we have an application where we can switch the Video Port back and forth between the 720p and 1080i modes for our captures.

    One final item/question:  I am having problem keeping sync with V-sync.  So sometimes when I start, I am capturing from the middle of a frame to the middle of the next frame (It does stay locked and doesn't 'roll').  Any ideas how I can get it to always start the Videoport Capture at the beginning of every frame?

    Thanks...

  • 0 in reply to JRasmussen
    TI__Expert 4935 points

    James,

     

    Are you using TI PSP drivers? This is taken care by the driver.

     

    If you are not using the TI drivers, then follow the following steps to start the capture.

    1. Enable BLKCAP bit in VCX_CTL register and disable VCEN bit

    2. Configure all the registers of VPORT.

    3. Program EDMA parameters and enable EDMA channels

    4. Enable VPORT using VCEN bit in VCX_CTL register

    5. Disable BLKCAP bit in VCX_CTL register

     

  • 0 in reply to Sivaraj R3681
    Intellectual 720 points

    Thanks for the Reply. 

    No, I am not using the PSP.

    I tried your suggestion and it helped make things more stable, but I still have the problem of the Picture's Video Sync being off after the Video Capture is turned off (via Blkcap & VCEN) and then turned back on.

    Is there some way to always get capture synced up with the First Line after Vsync?

    Thanks.

  • 0 in reply to JRasmussen
    TI__Expert 4935 points

    James,

    If you are restarting VPORT capture, then the problem is in reprogramming the working set of EDMA parameters.

    During capture operation the EDMA parameter (working set) is modified by EDMA. Hence the value of the parameters could be in the middle of a frame when capture is stopped.

    So before restarting the capture operation, reprogram the EDMA parameters. If you are using ping pong mechanism, then copy the ping parameters to the working set.

    Kindly do this, in between steps 2 and 3 in my previous communication. Also disbale EDMA channel when stopping the VPORT capture operation (do this after step 1)

    Hope this will solve your problem.

  • 0 in reply to Sivaraj R3681
    Intellectual 720 points

    Thanks Sivaraj,

    Resetting the EDMA counters did indeed do the trick.  It is working wonderfully now.