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YPrPb --> VGA

Discussion in 'Electronic Repair' started by Michael Kennedy, Dec 9, 2005.

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  1. I have a LCD projector that has VGA inputs and a DVD player that has YPrPb
    output. I was wondering if it were possible to wire the YPrPb directly to
    the VGA port. This probably depends on if the projector supports the non
    standard input or not, but I would like to know which pins I would need to
    connect the component video to.
     
  2. I tried hooking the Component video from my dvd player into a VGA cable and
    I get a picture in 480p mode but it is Green.
    There are no other colors present, just green..

    Any ideas??
     
  3. Guest

    I don't believe so. VGA is RGB and YPrPb is luminance, R-Y and B-Y.
    There is another hi-def standard that is slightly different. It might
    be called YCrBr. I don't know the exact difference in the signals but
    when I see a Y at the front I suspect it's also monochrome plus
    difference format.

    I could build a matrixing circuit to convert it to true RGB, but I
    can't do anything about the scan frequencies. Standard progressive scan
    from a DVD should be 31.5 Khz by 59.97 Hz. That would produce a raster
    with 480 usable lines scanned progressively.

    If it has an internal scan converter that can handle this timing, the
    other issue might be the native resolution of the projector. If it's
    not a multiple of 480 you might have artifacts. Best would be 960, 1440
    or 1920 pixels vertical resolution.

    If it allows for manual scaling you might get it to look good with
    other resolutions by not using the entire "screen".

    With all this, it's probably not worth persuing.

    Gotta go.

    JURB
     
  4. I did get my dvd player to work with my VGA monitor (viewsonic pf790) in
    480p mode but not 480i. There is one major problem though, the only color
    channel working is green. I'm pretty sure I have everything wired correctly,
    but there is no color but green.. With the exception of the screen on a
    movie preview that is solid blue with green letters that actually should be
    white.

    I've read this is possible with an xbox at
    http://www.xbox-linux.org/wiki/Xbox_VGA_HOWTO

    I'm also interested in making my xbox work with my monitor if possible.. I
    havn't tried this yet though. I was wanting to get it working with my dvd
    player first if possible.
     
  5. Dave D

    Dave D Guest

    Can't be done directly, component video and RGB are completely different
    formats. You might get a synced image, but you'll never get all the colours
    working.

    The difference is explained here:

    http://www.projectorcentral.com/component.htm

    Dave
     
  6. Dave D

    Dave D Guest

    Oops, just realised we're discussing a projector, not a VGA monitor. The
    above advice still stands *unless* your projector specifically supports
    component video via its 15 pin DSUB connector, as some do. If it does, the
    best thing to do might be to just buy the proper lead.

    Dave
     
  7. Andy Cuffe

    Andy Cuffe Guest

    You can buy converters for this for around $100-$200. Your DVD player
    needs to output progressive scan for it to work with a VGA input. I
    use one made by a company called Audio Authority for my video
    projector. A few DVD players will output RGB, but these are very
    rare. Every DVD player is capable of RGB, but the feature is almost
    never enabled.

    As others have said, it's a simple task in theory, but building
    something that would work well is not a trivial task.
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
     
  8. James Sweet

    James Sweet Guest



    It can be converted though for sure, a TV has to be able to decode it to
    RGB afterall, I suspect there's a single chip solution to do most of the
    work.
     
  9. Dave D

    Dave D Guest

    That depends where one lives. In some parts of the world, notably here in
    Europe, DVD players without RGB are exceptionally rare.

    Dave
     
  10. Do you mean RGB as in VGA or YPrPb where it has 3 phono jacks. I need VGA
    signal, it is not the exact same thing as RGB.
     
  11. Dave D

    Dave D Guest

    RGB as in TV standard RGB, not VGA.

    Have you checked the spec of your projector to see if it supports component
    video? Some do.

    Dave
     
  12. That is because of RGB to YYrYb or in your case YrYYb. So when you
    connect the G with Y you will have a green picture with the values of
    the luminance channel (if you had a white phosphor instead of the
    green one in your tube you would have a nice b/w picture) but the R
    and the B channels will not work with the other components.
     
  13. VGA is RGB but the RGB frequency is too low for VGA
     
  14. Andy Cuffe

    Andy Cuffe Guest

    VGA is RGB. YPrPb is component video and totally different from RGB
    despite the color of the connectors. If you have a player that
    outputs RGB, you just need the right cable to connect it to a VGA
    device (assuming it's outputting 480p or higher). Most devices with a
    VGA connector won't sync to 480i.
    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
     
  15. Andy Cuffe

    Andy Cuffe Guest

    That's actually a very good price. I paid almost twice that for a
    second hand box on ebay a couple of years ago. You can pay more than
    that for some video cables these days.

    Andy Cuffe

    <-- Use this address until 12/31/2005

    <-- Use this address after 12/31/2005
     
  16. You should check the options on your projector. Some are switchable to use
    either. If not you need a transcoder which can be found for about $100.

    VGA is discrete RGB, while component uses difference signals.

    Leonard
     
  17. Guest

    As I explained, you need a circuit to "dematrix" the color difference
    signals.

    JURB
     
  18. James Sweet

    James Sweet Guest

  19. Ray L. Volts

    Ray L. Volts Guest

    Good overview of the formats:

    http://www.keohi.com/keohihdtv/learnabout/definitions/rgb_vs_yprpb.html
     
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