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DVE and overscan

Discussion in 'Plasma TVs' started by Likvid, Mar 8, 2005.

  1. Likvid

    Likvid
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    On the Digital Video Essentials DVD there are an overscan pattern.

    There are markers for 10%, 5% overscan and so forth.......

    Where is the marker for 0%, it seems dead hard to adjust to 0% when there is no marker, the furthest it comes is two markers beyond the 2,5% mark, what value does those markers have?

    I am setting the overscan for my sat-receiver so i am feeding the RGB signal from my Denon 3910 thru the RGB2VGA JS Tech box to make it as close as possible to the sat-receiver, under reservations that both the Denon and the sat-receiver sends out the same signal values on RGB.
     
  2. hornydragon

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    you have to go to the very edge to get 0%
     
  3. Likvid

    Likvid
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    That is what makes the DVE pattern so hard.

    It's very diffucult to get it exactly right.

    Do you have 0% overscan on your plasma?

     
  4. hornydragon

    hornydragon
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    YEP not done by me but Piers and his sencore Sig gen (have done it in DVE (when i first got it) but why have a dog and bark yourself?) there is a link to a nokia monitor test pattern that may beof use mate try a search ("PC as a scaler" thread i think posted by Dave at plugged in TV)
     
  5. Bearded_Malc

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    But if you listen to what they say on DVE the 5% overscan point is action safe line and 10% the title safe line (AFAIR without checking). In other words all the action takes place inside the 5% line so you are not missing anything. Most TVs overscan. Films are shot so nothing important happens at the edge of the frame. That is why there is not a 0% line.
     
  6. hornydragon

    hornydragon
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    all you see at 0% is where the broadcaster get things wrong!!!
     
  7. GalacticaActual

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    Overscan the bain of the Viera owners life! :eek:

    I used dve to adjust the overscan on my Viera plasma. I adjusted every thing half way past the 5% line and found this to be just about perfect for every thing. :thumbsup:
     
  8. Likvid

    Likvid
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    Yes but i loose definition in the picture, 0% overscan gives me all available lines that are available which gives me a better picture.


     
  9. Bearded_Malc

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    Assuming you are watching PAL DVDs then they have 576 lines and if you are watching them on a standard definintion TV, 480 lines since they're all US standard, then you're not actually losing anything. In fact you could argue that an overscan of 20% would give a better picture as then you would get a 1:1 line to pixel mapping.
     
  10. hornydragon

    hornydragon
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    his screen is 1366x768 so he is not loosing res...........
     
  11. Bearded_Malc

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    I missed his screen size. Still 6.25% overscan would give a 2:3 line to pixel ratio whereas 0% is 3:4 lines to pixels. 2:3 may look sharper.
     
  12. Likvid

    Likvid
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    I don't get you there.....

    SD is 576 lines, with 6.25% overscan on all edges i will lose 144 lines total.

    By displaying 576 lines and 0% overscan i get the most out of the signal i can get, the image is much sharper than 5% overscan i had before.

     
  13. Bearded_Malc

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    My point was that with a SD screen you only have 480 lines so the screen has to map down. With a 1:1 you might get a sharper picture? With 768 then using just 512 lines would give 2:3 mapping which also might be sharper. Just displaying the entire picture on the screen may not give the sharpest picture.

    In an ideal world there would be 1:1 mapping or 1:2 mapping which means less adjustment but screens are always US sizes.
     
  14. Likvid

    Likvid
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    I am getting confused by all this.

    I tried 0% overscan on DVD and that works pretty good, but i can see a straight line at both side at the edges of the screen, maybe it's not good to have 0% overscan? maybe 1% or 2% is better.

    After reading some of EBU technical recommendations they say the overscan should be 3.5% all around.

    When i adjusted for 0% overscan i got black sidebars 18-20 pixels wide when watching TV-channels thru my sat-receiver, which explains the 702x576 instead of 720x576 for DVD production, 18 pixel goes to blanking and other picture information.

    So what should i set it at? what is the correct standard?

    0% overscan for DVD and 3.5% overscan for TV?

    Another thing is that the MPEG-2 picture is build up on 16x16 macroblocks so when adjusting overscan it should be an even integer, eg 720/16=45, 576/16=36 which is perfect if you have 0% overscan.

    Next step down is then 704x544, eg 704/16=44 and 544/16=35.
     
  15. hornydragon

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    i would go for 2.5% in general there is no need for 0% and for TV 5% is fine
     
  16. Likvid

    Likvid
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    How does it work in a scaler if i feed the 576i signal to the scaler and then the scaler translates it to 1366x768 for my panel?

    Would the scaler strip some of the picture or will it transfer it with 0% overscan?

     
  17. hornydragon

    hornydragon
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    I think you are getting confused between scaling and over scan they are not the same gordon and Piers know more than i do but with a PC monitor you dont get scaling like you do with a video dsiplay amonitor (PC) displays the pixels it sent a TV displays the lines both can be set with over scan/positioning to centre/fit the image the issue is with broadcasts not sending the same number of lines (yes they arrive but some maybe unused) so if you run 0% you grt noise around the very edge of your picture this is down to the broadcaster and there studio trnsmissions systems. While i understand you want to maximise the PQ you see losing one line here or there to overscan is no big issue. 576 doesnt map to 768 directly...........
     
  18. Likvid

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    DVE is no good for overscan, the whole image gets shifted to the left when watch DVD or similar afterwards
     
  19. GalacticaActual

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    Ah, could be something called rgb shift, that can happen on some displays. It also happens alot when playing video games. If you have a dvd player with componenet out puts. setting the overscan is not a problem with dve. Trust me I know, It gave me quite a headache when I first got my Viera plasma.
     
  20. Likvid

    Likvid
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    Yes, well i have to rent a signal generator for a day, the only thing you can really rely on.

     
  21. GalacticaActual

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    yep , good idear :smashin: :smashin:
     

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