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PC TV-Out: RGB AND Audio -> RGB Scart on TV?

Discussion in 'Nvidia' started by Shug, Jan 15, 2007.

  1. Shug

    Shug Guest

    Hi folks,

    I've currently got a PC with an s-video output which I plug into a
    SCART adapter on the back of my TV - the picture is ok, but nothing
    great. The cable is around 7metres long and the SCART adapter has
    s-video and audio L/R.

    I've got a new PC graphics card which has TV-out, including some
    attached connectors providing s-video and three phono sockets - Red,
    Green and Blue.

    My TV's other SCART input says it's "RGB / AV".

    My first question is - rather than using s-video connections, could I
    use component video by getting a long RGB to RGB cable (3 phono plugs
    at each end) and one of these:
    http://www.svideo.com/scartrgb.html

    (Or a 7metre RGB/YPbPr to SCART cable.)

    Secondly, to watch films etc, I'd obviously also want to take the
    output from my PC sound card and connect it to the SCART input on the
    TV somehow - so the adapter I really need would need to have RGB
    sockets AND Audio L/R.

    Any idea if this is feasible, and if such an adapter is available?

    Any help very much appreciated

    Shug
     
    Shug, Jan 15, 2007
    #1
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  2. Shug

    John Howells Guest

    NO. The use of the term RGB in that advert is HIGHLY misleading. The text
    states "Use it to inter-connect your devices that output YPbPr component
    analog video (CAV) to a television (or other device) that accepts component
    analog video." so it only connects devices that output component via SCART
    to a TV that accepts component via phono (and perhaps the other way round).
    It will *NOT* change the component output to connect to a SCART RGB input.

    You need something like
    http://www.js-technology.com/product_info.php?cPath=22&products_id=52. You
    may find alternatives on the Keene or Lektropacks sites. Inevitably such a
    unit will cost significantly more than the $7.95 of your item, as active
    electronics are required.

    Note also that SCART RGB requires five signals, as the sync is on a separate
    pin, and there is a further pin to say that the RGB is active (as opposed to
    composite), called "fast blanking". Not all units insist on the "fast
    blanking" being present, but some insist on it, and all insist on the sync
    connection. Your reference to an "RGB to RGB" cable should therefore be
    "component to component" if it's using 3 phonos.
    You will notice the item I referred to accepts the audio along with the
    component input and outputs it on the SCART socket.

    However, if the s-video from the new video card does not look like anything
    special don't be disappointed if the component outputs don't look much
    better, unless your video card is doing a bad job of the s-video compared to
    its component output. In the normal scheme of things the advantage of
    RGB/component (which are more or less equivalent for interlaced material)
    over s-video is not that great compared to the advantages of
    RGB/component/s-video over composite.

    John Howells
     
    John Howells, Jan 16, 2007
    #2
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  3. I wish I could write paragraphs of technical detail like John but I'll
    have to settle for : No

    Your TV doesn't (I assume) have component inputs, therefore you are not
    going to get a component quality picture. In fact you are extremely
    unlikely to get a better picture than you already have.

    To watch films on your TV you may find that the picture is ok - don't go
    off the quality of the desktop picture & look if your card supports 2nd
    output for TV.

    I have personally never seen one. The only scart adapters I have ever
    seen have composite or s-vid (both with audio).
     
    Resident Drunk, Jan 16, 2007
    #3
  4. Shug

    Shug Guest

    Thanks very much for your response, John.

    Apart from the misleading ad, can I assume my TV documentation isn't
    accurate as well then?

    It says RGB via SCART. Since I'm a newbie to these different video
    standards, I thought RGB and component were the same, and that it was
    providing a SCART socket rather than an additional three component
    input sockets?

    So are RGB and component different, and does my TV therefore NOT accept
    component input?

    So when a TV DOES have component input, it should say "component"
    rather than "RGB"?

    I'd initially seen a cable like this (although various other similar
    ones are available, both cheaper and dearer)
    http://www.tvcables.co.uk/cgi-bin/tvcables/PGV379.html

    and thought it would do, apart from the problem of getting the sound
    from the PC to the TV.

    I'd initially started looking for a component lead because other folk
    were saying it'd be better quality than s-video.

    Re the interlacing : i'm in the UK, so it's a PAL TV signal - does that
    infer interlacing or otherwise?

    Cheers

    Shug
     
    Shug, Jan 16, 2007
    #4
  5. Shug

    Shug Guest

    Thanks for responding RD.

    You're right - the TV only has two SCART inputs on the back - no
    separate component inputs.

    I (probably wrongly) thought that the manual specifying RGB on one of
    the SCARTS (s-video on the other) maybe meant that it could use a SCART
    plug to channel the component input signals into the TV's electronics.
    But I know nothing about TV electronics, so I'm really in the dark.
    Yeah, same here - I'm currently using the scart adapter you mention
    with s-video and L/R audio inputs. Just from reading other newsgroups,
    I'd got the impression that component in would be even better, but just
    looks like my TV doesn't have the electronics.

    I'm actually intending to use the PC with GB-PVR (bit like Windows
    Media Center) as a PVR as I'm experiencing problems with Media Center.
    So I only care about the TV/film picture, I'm not bothered about the
    desktop being pin-sharp. And it seems that both you and John have
    both said there won't be a great difference in quality between s-video
    and component.

    Thanks again

    Shug
     
    Shug, Jan 16, 2007
    #5
  6. RGB consists of the three primary colours distributed separately and at
    full bandwidth. Usually needs a separate syncs feed too as in a SCART -
    although these are sometimes combined with green for other uses.

    Component derives from a system designed for pro analogue tape recorders
    to reduce the bandwidth needed for RGB while given good results. Basically
    you have still three circuits - Luminance (R+G+B) at full bandwidth and
    two colour difference signals at lower bandwidth which by simple matrixing
    with the luminance produce the third. Colour information doesn't need the
    same bandwidth in analogue as the detail is provided by the luminance
    signal. All a bit irrelevant with digits, though, and I'm not quite clear
    why some countries prefer components to RGB for domestic use.
     
    Dave Plowman (News), Jan 16, 2007
    #6
  7. Shug

    John Howells Guest

    In terms of quality component and SCART RGB should be about the same. The
    display conversion from one to the other is a simple mathematical process,
    as described at http://www.fourcc.org/fccyvrgb.php. However, the sync signal
    is carried on the luminance (Y) signal in component and on a separate pin
    for SCART RGB, so as well as performing the arithmetic a conversion unit
    must extract the sync signal. The only reason for a difference in quality
    would be if the designer were to mess up the conversion electronics!
    Yes, RGB and component are different, and you would expect that most TVs
    accepting component would have the same three phono sockets as on your video
    card. However, there are occasional units that provide component input or
    output over a SCART socket using non-standard wiring.
    That cable would suit one of the occasional units noted, but there are not
    that many, and like the other unit you noted it will not provide the
    required conversion from component on the three phono connections to SCART
    RGB on the SCART plug.
    As I noted, the quality order (from worst to best) is:

    composite
    s-video
    component or SCART RGB

    but the step up from composite to s-video is far greater than that from
    s-video to the other two. If your card's s-video is not too good do not
    expect too much if you were to change to component or SCART RGB.
    Yes, it would imply interlacing. I only mentioned it because over component
    you can have "progressive", which is non-interlaced. Your video card should
    certainly be able to generate interlaced, and may be able to generate
    progressive, but that would only be relevant if the TV had component inputs.

    John Howells
     
    John Howells, Jan 16, 2007
    #7
  8. Shug

    JB Guest

    Hi Shug,

    Your PAL TV has two scarts - scart handles combinations of: composite,
    svideo and RGB.
    You will find (I suspect) that scart1 supports composite+RGB, but your
    scart2 only does composite+svideo.

    Your PC VGA card will output VGA as RGB and you can make a lead that
    delivers the RGB to your scart1.

    See http://www.idiots.org.uk/vga_rgb_scart/

    It requires some tweaking on the PC side to get the VGA card generating
    perfect PAL signals - you also need to generate output as interlaced
    (something I think only ATI Radeons support).

    If you think this sounds like a lot of effort - you're right it is.
    But I have an htpc (running MediaPortal) and using the svideo out on the
    ATI9700pro I found
    1/ I was locked to certain resolutions
    2/ The contrast was dull

    Using the VGA->SCART + Powerstrip method I now run at PAL friendly
    1024x576 on RGB.
    The picture is *much* better, as good as my other devices (DVD,STB) on RGB.

    Note: The svideo out on the VGA cards do provide some twitter filtering,
    which is lost - so desktop fonts/icons etc tend to flicker with the low
    res interlacing, but an htpc GUI that is designed for interlaced CRT use
    (i.e. avoids single pixel lines) looks just fine.

    HTH
    J.
     
    JB, Jan 20, 2007
    #8
  9. Shug

    Shug Guest

    Hi JB, and thanks for your response.

    You're right about my TV inputs.

    I'd previously been aware of the RGB method, but I'd seen a lead on
    offer for about £60.
    (http://www.microdirect.co.uk/productinfo.aspx?ProductID=12667)
    I couldn't afford that, just to try the RGB method out.

    In any case, I'd seen quite a few posts saying the component would be
    better than RGB, but also that s-video should be better than RGB. John
    seems to confirm this in his latest post above.

    I'm not bothered about getting composite now - and I don't have the
    appropriate (TV) connections anyway, but your 'RGB better than s-video'
    comment has perplexed me.

    Also, I don't have the right video card - I've got an nVidia 6200.

    If I knew for sure that it was a guaranteed _marked_ improvement with
    the Radeon/expensive lead, then I'd consider it in the future when
    I've got more time/money.

    Thanks

    shug
     
    Shug, Jan 22, 2007
    #9
  10. Shug

    Shug Guest

    Sorry JB, just re-read John's last post and you concur that RGB and
    Component are roughly the same. I'd read John's table of increasing
    quality the wrong way.

    My question would then appear to be - should I spend £60 on the lead I
    linked to above, to get the improvement from s-video to RGB.
    Apparently this jump in quality isn't as noticeable as from composite
    to s-video.

    Also, would my NVidia GeForce6200 card be able to handle the issues you
    mentioned...

    shug
     
    Shug, Jan 22, 2007
    #10
  11. Shug

    Shug Guest

    Thanks for all your advice John, you've been most helpful.

    This was just one problem in my HTPC (using GBPVR) setup, and I need to
    look into some of the other issues now.

    Thanks again.

    Shug
     
    Shug, Jan 22, 2007
    #11
  12. How are you with a soldering iron?
    Have you seen this? http://www.idiots.org.uk/vga_rgb_scart/
    I'm tempted myself if I can be arsed. Maybe one day I will

    Doc
     
    Dr Hfuhruhurr, Jan 23, 2007
    #12
  13. Shug

    Shug Guest

    Hey Doc,

    I might've been tempted, but that solution doesn't have sound included.
    I also need to get the sound from my PC to my SCART input.

    Unless, of course, it's easy to just add the sound lines while
    soldering...
     
    Shug, Jan 23, 2007
    #13
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