The converting scart RGB to RGBHV, or component problem

Discussion in 'Displays' started by David Payne, Mar 21, 2006.

  1. David Payne

    David Payne Stunt Coordinator

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    Okay, so having started two threads on projectors and done a great deal of research on the topic to help me buy my first projector, I've discovered an issue that at first I thought would be a minor projector issue, but turns out to be a big problem for many people - that is, the problem of connecting a scart RGB output from a DVD player or digibox to a projector (or sometimes TV), that only accepts component, RGBHV, RGBS or RGsB. I've seen a lot of threads all over the internet about this issue, but with very few solutions. This is obviously a big problem in Eurpoe, where scart RGB is very common, but componment and other forms of RGB syncs are not. So, I thought I'd start a thread where everyone who has experienced this problem can talk about it, and hopefully we'll get an idea of where the situation lies at the moment, and what the possible solutions are.

    So, is it worth getting a convertor to convert scart RGB into one of the formats you need? Or is the quality loss after conversion so much, that it's not worth it? What convertors exist? Am I right in thinking scart RGB -> YUV are the most common and cheaper? Is the difference between RGB and YUV small enough that this solution will be fine? Are there other ways you can get the picture to synchronize? For example, my TV has a habit of taking the RGB from the scart and sync from the composite sometimes (by accident I think, though!). Are there any projectors that do things like this, so that we can exploit it? Or should we just admit defeat and use S-Video? How does S-Video generally look on a projector, compared to RGB/YUV? I know it's an issue that's slowly going away as HDMI moves in as the standard connection, but I'd still like a solution in the meantime for SD DVD players and digiboxes.

    (And I'd be especially interested in hearing from BENQ PE7700 owners, because that's the one I'm looking at [​IMG] ).
     
  2. David Payne

    David Payne Stunt Coordinator

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    Oddly enough I've started to find some things on the net that look promising. According to this it's at least possible: http://www.tkk.fi/Misc/Electronics/f...rgb/scart.html

    As long as you're willing to do some home soldering!

    And here'e a device that seems to be able to convert RGsB to RGBHV, although the descriptions a bit vague. And you'd need to get your scart RGB converted to RGsB in the first place! But, it all looks promising!
     
  3. Shane Harg

    Shane Harg Second Unit

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    You've got to be kidding me!!! Why don't you simply look into into a projector option, which actually has a SCART input??? (see my other longer post on your other thread)
     
  4. David Payne

    David Payne Stunt Coordinator

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    I didn't say I was actually going to do that, just that it shows promise that the problem is solvable! [​IMG]
     
  5. Joel...Lane

    Joel...Lane Second Unit

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    David,

    Is this the type of cable you're looking for?
     
  6. ChrisWiggles

    ChrisWiggles Producer

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    You need a trascoder it sounds like.
     
  7. David Payne

    David Payne Stunt Coordinator

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    If a transcoder is something that converts scart RGB (RGBS?) to YUV or RGBHV, then I think that's definately what I need! [​IMG]

    Any idea where I could get such a thing?
     
  8. David Payne

    David Payne Stunt Coordinator

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    Okay, I e-mailed the site Joel...Lane linked to to ask them about that cable, and this is the reply I got:


    Is that guy right? It sounds like he's saying RGsB and YPrPb are the same thing! And scart leads don't use RGsB anyway, so I don't know how that cable's meant to work!
     
  9. Joel...Lane

    Joel...Lane Second Unit

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    Hmm...don't know to be honest. I mean, it's a cable designed specifically for the uk. I'm sure it will work fine.

    Check their return policy and if it's decent then get it and try it out.

    Good luck!
     
  10. David Payne

    David Payne Stunt Coordinator

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    Finally, I did a search using the term transcoder (thanks ChrisWiggles!) and found there are a few things on the market that will do the job. Like this: http://www.js-technology.com/product...494ebcbb09c5da - basically it's a scart RGB to RGBHV/VGA, from the looks of it. Bit pricey, but at least now I'm positive I don't have to pigeonhole myself into using one type of connector for SD.
     
  11. Allan Jayne

    Allan Jayne Cinematographer

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    >>> Is that guy right? It sounds like he's saying RGsB and YPrPb are the same thing! And scart leads don't use RGsB anyway, so I don't know how that cable's meant to work!

    RGsB and Y/Pb/Pr are completely different and a transcoder is needed to go from one to the other. In lay terms (with only a vague resemblance to the real thing) think about how to get red, green, and blue given red, white (luminance) and blue.

    RGsB (three wires) and RGBS (four wires) exist as standard formats in the U.S. also. SCART RGB is sufficiently similar to U.S. RGBS that you will usually get a very watchable picture once you massage the sync. line to match (RGBHV or RGsB) if needed. There are slight normalization constant differences resulting in slight color mixture incorrectness but adjusting red gain, etc. you should be able to calibrate everything right without a transcoder. I think there are also slight differences in the waveform shape of the sync. (front porch, etc.) and a few TV's that don't specifically accept SCART RGB may not sync. to a SCART RGB signal. In the U.S. there are two sync. waveform standards, SMPTE for entertainment video and VESA for computer video and most but not all devices work with both interchangeably.

    Depending on the source device, a SCART output can deliver composite or Y/Pb/Pr instead of RGB. You will have to refer to the instruction manual to find out which or whether you have a choice.

    Do be aware that Y/Pb/Pr and all 3 RGB formats come in a variety of scan rates: 480i, 576i, 720p, etc. Here you must have a match between the source device and the TV, or put a scaler in between.

    S-video is somewhat inferior in quality to Y/Pb/Pr and all three of the RGB formats.

    Some TV's accept RGBS using the yellow jack for the sync. Some SCART sources expect you to use composite video delivered simultaneously with the RGB as your sync. except that some TV's require that the (positive going) video be stripped from the (negative going) sync. before that signal is acceptable as the S of RGBS.


    Video hints:
    http://members.aol.com/ajaynejr/compon.htm
     

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