1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

RGB vs SVideo vs composite. Whats the difference?

Discussion in 'General TV Discussions Forum' started by nunew33, Jul 29, 2002.

  1. nunew33

    nunew33
    Standard Member

    Joined:
    Jun 5, 2002
    Messages:
    1,736
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    41
    Location:
    Lytham St Annes, where people are put out to grass
    Ratings:
    +2
    I understand the technological differences between these standards and why, in theory, the images should be improved as you go from composite to svideo and svideo to RGB.

    But Im beginning to think I am blind as no matter how hard I try I can only see marginal improvements on my 29 inch Sony Trinitron. I use the RGB setting for Sky, used to use it for DVD which has now been relegated to the Svideo socket. I cant see that much difference in quality (except maybe on menus which are hardly the focus of what Sky and DVD players are for). At most I would say that there was only a 1-5% improvement from composite to either svideo and RGB and its so marginal that if I used the composite image instead of RGB that II wouldnt really notice.
    If these were optional upgrades to the TV then I would find it hard to justify the extra expense.

    So can some one tell me:
    a) Am I blind
    b) Have I neglected some tweak somewhere
    c) Is RGB/Svid/Composite obsession just another stream of av upgraditis
    d) Is there really not that significant a difference when you are sat watching a movie or soap which afterall is what the TV is good at.

    What I really suspect is that a general bulk standard TV isnt really going to show any difference but the higher spec/bigger screen you go more significant it becomes.
     
  2. Zacabeb

    Zacabeb
    Active Member

    Joined:
    Jan 17, 2002
    Messages:
    474
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +9
    Well, here is the real problem:

    'Normal' viewers watch TV at factory settings, where contrast, color and sharpness are set way too high. That means pushing the set and the human eye beyond what they were made for, and leads to a blurry image. I do not know why 'normal' people want faces to look like radioactive tomatoes, but they apparently do.

    And that is why we are seeing all sorts of annoying 'improvements'. The 'normal' viewers never ever got to see a truly high quality picture. They are totally unfamiliar with genuine picture quality. Had they ever taken the opportunity to turn down the contrast on their old TV, they would have entered a whole new world. But they did not.

    For people who have never seen a sharp picture before, all these features are improvements indeed. But for those of us who were used to a razor sharp, undistorted reproduction, TV's have become significantly impaired. The difference in performance between signal types seems lesser on newer TV's and it is not just because they 'improve' the lesser signals. It is also because they impair the best. Even RGB gets a rough, smudgy look thanks to this.

    100Hz TV's are the worst culprits as they started appearing way before DVD, DTV and video games. Originally they were made mostly to handle composite signals and the digital circuitry was designed thereafter. In spite of all the 'improvements' like Pixel Plus, DRC and whatnot - which are done live as the image is output - the basic processing is nearly as primitive as it ever was. The standard field memory is only 3Mbit in size, and to store a whole video field in there, the color must be lowered in resolution or compressed. As a result, 100Hz TV's never give full color resolution via RGB, but reduce it almost down to S-video quality.

    So that is pretty much it. Composite may be comb filtered and if it was well encoded, look fairly sharp and only slightly inferior to S-video. RGB is reduded in quality by crummy digital processing. The differences are greater than most TV's are able to reproduce.
     
  3. nunew33

    nunew33
    Standard Member

    Joined:
    Jun 5, 2002
    Messages:
    1,736
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    41
    Location:
    Lytham St Annes, where people are put out to grass
    Ratings:
    +2
    So in a nutshell I have a crap TV!!!

    I have discovered the power of altering factory settings and I too am amazed at how my relatives like skin tones on their TVs to reflect those of your average blackpool ladess and her carrot coloured bottle tan, so its not that I am happy to accept a crumby picture its just that I cant seem to tweak a substantial difference between the three.

    If the TV negates differences then, with 2 scarts (1 RGB, 1 SVid) on the TV and DVD/Digibox/VCR (SVHS), there is no point worrying about how I configure them to get optimum picture I may as well go for:

    RGBScartTV <- Digibox (no svid) (loopthrough) <- VCR(SVHS)
    SVidScartTV <- DVD

    As opposed to a more complicated:

    RGBStartTV <-DVD (RGB loopthrough)<-Digibox (loopthriough)<-VCR
    SVidScartTV <-VCR

    Just asanity check SVHS and Svideo are not connected (are they?) so I will still get a sharper than VHS picture from SVHS on the VCR, just composite (as no RGB out, just SVid))
     
  4. Zacabeb

    Zacabeb
    Active Member

    Joined:
    Jan 17, 2002
    Messages:
    474
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +9
    I think you should aim to connect all RGB-compatible devices, both digibox and DVD to the RGB SCART and your S-VHS to the S-video SCART. You will get a better quality picture from your VCR with S-video than with composite video and you may get a better DVD picture through RGB than with S-video. There are still differences, they are just smaller than they should have been.

    S-video was introduced thanks to S-VHS and Hi8, but S-VHS itself does not have anything to do with it. Both VHS and S-VHS record luma and chroma separately, but S-VHS records luma at higher frequencies giving higher sharpness. S-VHS decks have S-video outputs and comb filters as standard because it makes sense there, but there are marginal benefits also for regular VHS.
     
  5. nunew33

    nunew33
    Standard Member

    Joined:
    Jun 5, 2002
    Messages:
    1,736
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    41
    Location:
    Lytham St Annes, where people are put out to grass
    Ratings:
    +2
    Thanks Zacabeb, youve been very helpful, cleared a few issues that I wasnt too sure about.
     
  6. pwoody

    pwoody
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I can see the diff between the various types but find RGB to be less sharp on my 28in Philips when viewing my satellite Sony box set to RGB. Colours seem better but the sharpness is not as good. I seem to remeber a previous posting about this but it was a tad technical. As you seem to be able to simplify things I would appreciate you thoughts on this.
     
  7. nunew33

    nunew33
    Standard Member

    Joined:
    Jun 5, 2002
    Messages:
    1,736
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    41
    Location:
    Lytham St Annes, where people are put out to grass
    Ratings:
    +2
    I can see the difference on mine, but could you honestly say there was more than a 5% difference (in overall picture quality - eg RGB edges are crisper but the colours seem softer to the extent that it seems a bit washed so one good effect is negated by a bad effect) between the three standards when viewing from say 3metres away.
     
  8. MartinImber

    MartinImber
    Active Member

    Joined:
    Apr 5, 2001
    Messages:
    3,854
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    71
    Location:
    Worcester
    Ratings:
    +21
    How about TV autosensing RGB as some RGB/Composite devices always output RGB as well as composite - they just switch it
     

Share This Page

Loading...