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DM365 10-bit BT.656 Downstream ramifications

Paul Stuart62744
Prodigy 130 points

Hi 

I am capturing 10-bit BT.656 from a TVP5147 on a custom, DM365-based, board. After the joy of verifying that I was in fact receiving correct video, the realization that nothing downstream was working sunk in. 

When capturing 10-bit BT.656, each component for Y, Cb, Cr, is packed into 16 
bits, vs 8 bits for 8-bit BT.656. So, now one needs 32 bits for every 
pixels vs 16 bits per pixels.

As far as I can tell, the VPBE will not display this format. Every mention of YUV422 format indicates it wants 16 bits per pixel. It simply 
can't display the captured data correctly. If I use the CPU to shave off the two LSBs and repack it into 16 bits per pixel, the display looks fine, but obviously slooooow.

I've also heard that the codecs won't accept 32 bits per pixel

I'm perplexed why 10-bit BT.656 is even an option if nothing downstream can make use of it.

Can anyone shed any light into any of the following:
Does anything in the encoder or display side actually work with 32 bits per pixel or is it in fact limited to 16 bits per pixel?
If it can be made to work, any hints would be appreciated :)
If it is a given that nothing works downstream with 32-bit pixels, is there a way on the front-end to shave off the two LSBs? Otherwise we will have to pursue HW changes.

Thanks,
Paul
  • 0
    Intellectual 610 points

    Paul,

    I am suffering a similar problem. I have been successful in setting up my BT.656 interface for 8 bit mode but I cannot get the 10 bit mode (with the appropriate H/W changes) to work correctly.

    Has anyone found an answer to Paul's original question?

    Tom

  • 0 in reply to Thomas Mitchell
    Guru 31670 points

    Tom,

    Which is the SoC that you are using? Can you list down the  10-bit pin connections, if possible share the portion of schematic? Also are you sure that you are configuring the pinmux settings correctly?

  • 0 in reply to Renjith Thomas
    Intellectual 610 points

    Renjith,

     

    I am using the TMS320DM365ZCE30. The interface from the video chip to the DM365 is BT.656 with a 27MHz DVCLK. My Video Chip supports both 8 and 10 bit data on the BT.656 interface. For a 8 bit connection I have connected DV2-DV9 from my video chip to CIN0-CIN7 on the DM365 and the DVCLK to PCLK. This works correctly and I'm able to look at the data in memory and see my image. Teh place I'm examining for a correct picture is in memory after the ISIF.

    When I connect the unit up for 10 bit data, i.e. DV0-DV7 to CIN0-CIN7 and DV8-DV9 to YIN0-YIN1 I get data in memory but I can't seem to determine the format so I can see what the picture looks like to determine if it is OK. I get a very distorted (both in contnet and color) picture. I have rechecked my PINMUX settings and all seems correct. What is the format of the data in memory after the ISIF when using 10 bit mode in BT.656? Any suggestions on a program I can use to view the image at that point?

     

  • 0 in reply to Thomas Mitchell
    Guru 31670 points

    Thomas,

    Can you upload the dump of both the files 8-bit and 10-bit? Also which is the video decoder that you are using?