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TVP5158 with DM6467 EVM - 1channel (seperate), Non-interleaved mode - video capture - Problem (back and forth of video frames)

Santoshkumar Pattar
Intellectual 515 points
Other Parts Discussed in Thread: TVP5158, TVP5147

Hi Viet  and All,

I am  having a setup in which TVP5158 EVM is connected to DM6467 EVM. The mode in which it is operating is that – on  DM6467 VPIF video capture channel 0(Zero),  it gets one video  stream from TVP5158 and on  VPIF video capture channel 1(one) it gets another video  stream from TVP5158. That is video captures are independent and not interleaved. Only two video inputs are taken from TVP5158. Other two are disabled.

 

The problem what i am facing is that – The video captured frames have back and forth motion. That is when i see the captured video i feel like some of the old frame are repeated after few frames.

I have timestamp for each of the captured frame. The timestamp differences between each video captured frame is always increasing and according to the expected value.

 The TI TVP5158 driver does not support independent video capture, i have written TVP5158 driver just like TVP5147 driver. And TVP5158 driver is registered to V4L2 just like TVP5147 driver.

 

  If I now just disable TVP5158 driver and enable TVP5147 driver the video capture happens fine. So there is no difference between the V4L2 driver(which does the video buffer management) when we use TVP5158 or TVP5147 driver.

 

Can there be any TVP5158 settings which might be causing this? Because V4L2 driver is the same and TVP5147 works fine but not TVP5158.

 

If anybody has any clues on this problem, please share your thoughts.

 

Thank you,

Santosh

 

 

  • 0
    TI__Expert 6120 points

    Hello Santosh,

    Recommend that you try using the 2-Ch D1 line-interleaved mode.  The line-interleaved mode was specifically designed for use with the DM6467.

    We don't recommend or support using the non-interleaved mode with the DM6467.  In the non-interleaved mode, the output clock is a fixed 27MHz frequency.  This causes the EAV2SAV interval to vary from line to line which is known to cause issues with certain back-end devices.

    Regards,

    Jim

  • 0 in reply to James Nave
    Intellectual 515 points

    Hi Jim,

    Thanks for the reply.

    We understand that you are recommending to use line-interleaved mode. But that is not our use case.

    "In the non-interleaved mode, the output clock is a fixed 27MHz frequency"    What do you mean by this statement? And how this will effect the EAV2SAV timings?

    1) When you say that EAV2SAV interval vary does it mean that the number of clocks for EAV2SAV length varies?  

    2)  For NTSC BT656 - The clock requirement is 27MHz. So if TVP5158 is giving 27MHz to both ports, why do u think this is the problem?

    3) Even TVP5147 gives 27MHz to VPIF there we dont see any problem.

    In the follwoing link http://e2e.ti.com/support/data_converters/videoconverters/f/376/t/51502.aspx The same problem has been discussed. And it has been suggested to "but add a driver in 27MHz clock circuit(a CPLD),they fixed the issue."  What do mean by this?

    Thank you,

    Santosh

     

     

     

  • 0 in reply to Santoshkumar Pattar
    TI__Expert 6120 points

    Hello Santosh,

    Here's the answers to your questions.

    1.  Yes, the number of clock cycles in the EAV2SAV interval will vary as required to maintain horizontal synchronization.

    2.  You need to program the DM6467 for a specific EAV2SAV interval.  When using the non-interleaved mode, the EAV2SAV is continually changing.  The TVP5158 and DM6467 must always agree on the length of the EAV2SAV interval.

    3.  The TVP5147 output clock is a line-locked clock.  It generates a fixed number of clock cycles per line and is locked to the input line rate.  The TVP5158 output clock is a fixed frequency.  The number of clock cycles per line varies with the input line rate.

    Again, the line-interleaved mode was specifically designed for the DM6467.  We are not aware of any other approach to reliably interface the TVP5158 to the DM6467.

    Recommend that you try using the 2-Ch D1 line-interleaved mode in your application.  The line-interleaved modes have been thoroughly tested with the DM6467.

    Regards,

    Jim

  • 0 in reply to James Nave
    Intellectual 515 points

    Hi Jim,

    Thanks a lot for your detailed mail. I really appreciate your quick response.

    Regards,

    Santosh