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Video output issue with DM6435 EVM loopback demo

R&D10371
Intellectual 730 points

Hello!

I'm making some tests with the loopback demo in DM6435 EVM. I'm trying with digital video and also with analog video at the EVM input. I checked this video is OK. Then I analyze both outputs, S-VIDEO and COMPOSITE and the problem is that in all the combinations the output video is ok in shape but only green and pink in colour (more or less green for the dark ones and pink for the light ones).

Any idea why this might be happening? It worked perfectly some time ago and we think nothing has changed.

On the other hand I was trying to use the CCS Image viewer to check the video at different points in the application, but I've found out that it seems the video is being redirected from the VPFE to the VPBE directly. Any ideas?

Thanks in advance!

  • 0
    TI__Mastermind 41665 points

    R&D said:

    Then I analyze both outputs, S-VIDEO and COMPOSITE and the problem is that in all the combinations the output video is ok in shape but only green and pink in colour (more or less green for the dark ones and pink for the light ones).

    Any idea why this might be happening? It worked perfectly some time ago and we think nothing has changed.

    The green and pink color is usually a sign of luma/chroma swapping, that is your color values are your brightness values and vice versa. When I have seen this in the past capturing digital video from a daughtercard it usually meant I was getting some kind of noise on the transmission to the board that led to the capture being off by one byte, at which point depending on how I bent my cable I could get it to flicker between proper color and the green/pink mess.

    R&D said:
    On the other hand I was trying to use the CCS Image viewer to check the video at different points in the application, but I've found out that it seems the video is being redirected from the VPFE to the VPBE directly. Any ideas?

    Which application are you using? Any of the demo applications I have seen leverage the capture and display drivers which implies that the video is buffered in DDR in between the capture and display drivers.

  • 0 in reply to Bernie Thompson TI
    Intellectual 730 points

    Thanks Bernie, and sorry for the delay in my answer.

    I tried swapping luminance and crominance by changing the CCDCFG register and it aparently worked. The problem was that I think Cr and Cb crominances were swapped (red colours were shown as blue and viceversa). So I tried to swap them by changing the PCR register but the result is not affected. I don't know why...

    I'm using an application provided with CCS, I think. It's a video loopback demo. I'm still working with it.