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Video frame shift problem help required

Thiyana
Prodigy 20 points

Hi

We are using DM642 to capture and encode the video. We see that for some time( may be for about 30mins) the video looks fine , later we see a frame shift or a split in the video vertiacally. Below are the details.

Problem Description

Vertical split in the captured video of Video Port1 Channel B is observed. The shift in the captured video frame remains the same through out the capture process (i.e. for 320x240 the amount of pixel shifted is 58 pixels to the right). This issue occurs randomly either after 10 minutes or 12 hours of capturing.

 

Video Port Configuration

DM642 DSP chip is being used for video capture and compression. It is interfaced with the Techwell decoder for capturing video in 4:2:2 format.

Video Port1 and Port2 of DM642 is used to capture real time video from TW2816 decoder (Video Port 0 is unused). Both ports are configured in Dual Channel BT.656 operation (i.e both channels of video port are used for real time capture).

Each Video Port Channel is configured to capture 704x480 NTSC Image and Control pins of Video Port1/2 are pulled high.

 Hope the to get help on this issue , any suggestion that i could try out and any thing wrong the configuration.

Thanks & Regards

TM.

  • 0
    TI__Mastermind 41665 points

    Could you post a screen capture of the output image so we can be perfectly clear on the issue you are seeing?

    If this is what I imagine, I suspect you may have run into an issue where the video port is out of sync with the EDMA which can lead to the image being shifted horizontally and/or vertically depending on when the desynchronization happens relative to the frame syncs (often with both leading to a cross forming in the video). In the past I have seen this when a video cable was disconnected and reconnected repeatedly from the video decoder eventually leading to where one of the disconnect/reconnect sequences got the capture out of sync.

    If you can detect this (for example if your decoder provides a disconnect event), you should be able to clear the out of sync condition with a call to FVID_control(fvidChan, VPORT_CMD_COVR_RECOVER, NULL); which will resynchronize the EDMA with the video ports and should get a solid image again, though this does take time to run so you do not want to call it constantly.

    Of course you could be seeing something else, it is hard to say without seeing an output image.

  • 0 in reply to Bernie Thompson TI
    Prodigy 20 points

    Hi Bernie,

    Thanks a lot for the prompt reply.

    Here we are not connecting and disconnecting the video cable. What happens is that in the initial stage may for about 30 mins or even for 2 hrs the captured video looks pretty good, but later the frame shift occurs. The split video stays the same may be sometimes for about 20 mins to max  24hrs etc... .  Below is attached the frame , when frame shift has occured.

     

    AM configuring the DM642 to dual channel mode , we are capturing 4 channels of video. This issue is seen only on one of the channels (always on that same channel). What we are doing at the moment is that when a frame shift occurs , just check for the blank line at the start of the frame and call the FVID_control(fvidChan, VPORT_CMD_COVR_RECOVER, NULL) as a work around, which i see is a over head some times.

    Is there any other better way to identify this problem and correct it.

    Best Regards

    Thiyana