Grass Valley 100N & Computer VGA input

Discussion in 'Professional Video Production' started by Thomas Kim, Aug 26, 2008.

  1. Thomas Kim

    Thomas Kim Guest


    My church has a Grass Valley 100N video mixer/switcher. We have an
    old compix gen pc attached to it. I would like to throw away the
    compix pc (pentium 3 and win 95) with more decent PC. The compix pc
    is sending out microsoft powerpoint slides to the mixer and mixer is
    sending out the signal to the over head projector.

    Can i just get a video card with svideo and a converter (svideo to bnc
    female) and connect it to the mixer? Do i have to get a genlock board
    and connect the genlock board to the mixer?


    Thomas Kim, Aug 26, 2008
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  2. "Thomas Kim" wrote ...
    You didn't mention whether you have anything ELSE coming into
    the GVG switcher?

    If the computer is the ONLY source, then just feed it directly into
    the projector, why do you even need the switcher?

    If there are OTHER inputs to the switcher, they are all presumably
    gen-locked to some (undisclosed) central source. (Since the GVG
    100 switcher requires gen-locked inputs).

    If you must switch between the computer and other video sources,
    you appear to have three options:

    1) Replace the old "compix" with annother computer video output
    that allows you to gen-lock the video to the system reference.
    Note that this may be an external VGA to NTSC converter
    which has genlock capability.

    2) Run the NTSC video from your new computer video card
    through a frame-synchronizer (or TBC) to create a gen-locked
    version of the computer video. There are 2nd-hand TBCs on
    eBay frequently that would likely do the job. And maybe at a
    total price less than solution #1

    3) Use the computer video itself as the system genlock source,
    assuming you have some control somewhere along the line to
    "time" the video. This is practically zero-cost, but has the great
    downside that the entire system is dependent on the computer
    video. That means big glitches in the video (rendering it non-
    recordable, etc.) if you re-boot the computer, for example.
    Only you can determine whether this cost-benefit is positive.
    Richard Crowley, Aug 27, 2008
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  3. Thomas Kim

    Bill Fright Guest

    If you're ppts are very detailed you might set up a vga switch so you
    can use straight vga or the output of the switcher. This way your
    graphics don't have to be compressed to composite NTSC. It's a little
    pricey but you can get a synced switch for your application. It will
    give you transitions too. Almost every computer has VGA out so that will
    simplify your solution.

    I'm assuming you have other sources in the switcher.

    Good luck and let us know!

    Bill Fright, Aug 27, 2008
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