DVI, 75 Hz, and messed up video playback

Discussion in 'PC Hardware, Software and Displays' started by Crusher, Dec 11, 2006.

  1. Crusher

    Crusher Aptitudinal Constituent
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    So I've noticed for a while now that when I play video (either DVDs with PowerDVD or mpeg/avi/wmv movies in WMP9) on my LCD monitor that the video is all wavy/distorted. The past few days I've tried to troubleshoot this without much success, but I have found a couple of threads with my googling where it seems other people have had this problem. Here is one example:

    http://www.short-media.com/forum/showthread.php?t=35219

    That seems to be almost an identical situation as I am in. I have a 6600 GT connected to a Viewsonic VX922 via DVI, and I have tried uninstalling/reinstalling all of my codecs and PowerDVD. If I turn my refresh rate down to 60 Hz instead of 75 Hz, it plays fine. If I leave it at 75 Hz and disable DirectDraw (via dxdiag) it plays fine. But at 75 Hz with DirectDraw enabled, it's garbled.

    Anyone have any idea what the problem is, and how I could correct it so it plays fine at 75 Hz?
     
  2. Skrying

    Skrying S K R Y I N G
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    Maybe your LCD does not play well at 75Hz?
     
  3. Crusher

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    Everything else is fine at 75 Hz (Windows GUI, Java GUI, games, etc.). Only video playback is messed up.
     
  4. Moloch

    Moloch God of Wicked Games
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    Is there some reason you want to run your lcd at 75hz :?:
    Doesn't seem to make much sense to me given the way they work :???:
     
  5. Crusher

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    I'm not quite sure what that has to do with my question, but the answer would be something to the effect of "because I like to have my games update as fast as possible and I hate having to have the display adapter switch modes when I start or alt-tab into/out of a game."

    And if you're trying to get overly semantic, no, it's not the LCD running at 75 Hz, it's the display adapter, but that's besides the point.
     
    #5 Crusher, Dec 11, 2006
    Last edited by a moderator: Dec 11, 2006
  6. Captain Chickenpants

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    Hmm, it sounds to me like there might be is some issue with the Overlay hardware and DVI.
    If you can try do a screen capture with DDraw enabled and disabled. What you should see is that when you look at the screen capture when ddraw is disabled you should see the video in the player window, when it is enabled there should be an empty box.

    You don't mention what resolution you are running at, can you verify the results at a lower resolution as well?

    CC
     
  7. Crusher

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    That is correct.

    I normally run at 1280x1024 (native for the dispaly). The problem does not appear to occur at 1152x864 @ 75 Hz, nor at 1024x768 at either 60 Hz or 75 Hz. It does still occur at 1280x1024x16bpp @ 75 Hz.
     
  8. Captain Chickenpants

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    OK, it sounds like there is some problem with the overlay pipeline. Can you try getting hold of one of those apps that allows you to generate your own display timing (e.g. powerstrip).

    Try tweaking the pixel clock frequency using powerstrip. A slight change to the frequency should have no ill effects on your display mode, but may help your wavey line problem. Sometimes you can get interference between clocks / buses changing the frequency that one of them is running at can sometimes get rid of the problem.

    Note this is just a guess at what the problem is on my part!

    CC
     
  9. Moloch

    Moloch God of Wicked Games
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    You run with vsync or something?
     
  10. Crusher

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    Vsync and triple buffering whenever possible, yes.
     
  11. Captain Chickenpants

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    Any luck with changing the pixel clocks?
     
  12. Crusher

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    I haven't tried yet, I'll make time tonight and let you know.
     
  13. Crusher

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    I set some custom timings in the nvidia control panel and it seems to have cleared up the issue. Thanks.
     
  14. Captain Chickenpants

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