Upgraded resolution - Views?

Discussion in 'Desktop & Laptop Computers Forum' started by JohnAd, Mar 15, 2001.

  1. JohnAd

    JohnAd
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    Neil

    What refresh rate are you using, does your projector support 72/75?

    In general higher is better but as you have an unmodded card the picture may get softer at higher resolutions and refresh rates.

    John
     
  2. Jenz

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  3. JohnAd

    JohnAd
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    I would recommend getting [email protected] set up for PAL stuff.

    When you play r1 stuff at 60Hz or any PAL stuff through the system do you not get loads of motion artefacts?

    It might be just me as I have working on the judder reduction code in dTV and am now pretty sensitive to it.

    John
     
  4. Jenz

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    No John, no judder or motion artefacts. Have you got a specific example I might try and use?

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    Bullets n Babes DVDs HT Pics
     
  5. JohnAd

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    Warning, do not read this post if you don't want the end up in tweeker hell ....

    The problem I'm talking about is that if you run a R1 disc at 60Hz you get the 3:2 pulldown pattern. What that means is that the individual film frames are not shown for the same amount of time.

    The best shots to show up this problem are slow panning shots. Mark R's fav demo is is a scene from Titanic but I was using the opening sequence from "The Shining" to test dTV. There is also the Jack Rabbit slim scene from Pulp Fiction. Also any slow upwardly moving credits sequence also illustrates this problem.

    OK so what to look for, basically film motion is 24fps which isn't really fast enough for the brain to be happy that motion is smooth. However film displayed at 72Hz at least gives you the best chance for you brain to go with the flow and tell you that the objects on screen are moving properly.

    At 48Hz you get the following 3x3 pixel frames displayed. For 72Hz you get three of each
    Code:
    00--  00--  ---- ---- ---- ----
    00--  00--  --00 --00 ---- ----
    ----  ----  --00 --00 ---0 ---0
    
    At 60 Hz you get the following 3x3 pixel frames displayed.
    Code:
    00--  00--  ---- ---- ---- ---- ----
    00--  00--  --00 --00 --00 ---- ----
    ----  ----  --00 --00 --00 ---0 ---0
    
    The middle set where the same frame is displayed three times makes it hard for your brain to accept the object is moving smoothly and your brain sort of does a double take and you preceive that object is moving in discreet jumps (i.e. juddering)

    If you don't notice this problem then don't worry about it, if you didn't notice it before but now that I've told you it is really annoying I can only apologise [​IMG]

    With a HCPC you can run at 72/75 for NTSC/PAL which avoids the problem also the latest version of dTV (not released yet) has code in to adjust for this.

    The same sort of thing will also apply to showing 50Hz pal stuff at 60Hz or 72Hz except the pattern will be more irregular. (In the above replace 24Hz with 25Hz and 72Hz with 75Hz for PAL)

    John

    [This message has been edited by JohnAd (edited 15-03-2001).]
     
  6. Jenz

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  7. JohnAd

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    Correct, if you're used to smoothness 3:2 pulldown at 60Hz is very annoying for those of us raised on 50Hz. The Americans seem to just ignore it much as we get very used to 50Hz flicker which they can't tolerate.

    John
     
  8. Jenz

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    Of the systems you've seen then what refresh rate and at what res were you "blown away" if at all.
     
  9. JohnAd

    JohnAd
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    Here is where I have to come out of the closet as a very inexperienced (in terms of system exposure) person.

    My HT is still in the planning phase .... I'm waiting to move somewhere with a bit more room, this should happen sometime this year. My efforts on dTV were originally part of my plan to do this as cheaply as possible to avoid upsetting 'er indoors.

    So in terms of being blown away, not yet...

    My general impression from reading other posts is that the correct resolution with a CRT involves the focus spot size and all sorts of other things which to be honest I don't fully understand.

    I can definitly say that it is not worth trying to get extra resoloution at the expense of running at a film multiple refresh rate. If the image looks solid at 800x600 you will not gain anything by going to 1024x768

    I run all my tests on a fixed 1024x768 monitor. On this 72/75 looks the best by a long way except that I get some softness at those rates probably due to cheap cables.

    John
     
  10. Jenz

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    I was fortunate enough yesterday to have my Barco 708MM recalibrated by a Professional Projector Engineer.

    Whilst doing the setup we took the chance to add some specific additional resolutions correctly configured. Previously we had settled on resolutions of 640x480 and 800x600 (the preferred resolution).

    Last night we added 1024x768 to the setup. All versions are now available in both 4:3 and 16:9 modes.

    I have begun to test the higher resolution to see if there are discernable improvements/problems with this higher resolution.

    Clearly the immediate benefit is that scan lines visible from 2 feet away from the screen on 800x600, are no longer visible on 1024x768. Scan lines are visible at about 6inches. How this relates to DVD viewing I have yet to determine.

    I was wondering if anyone has gone through a similar exercise and what if any conclusions you had come to?

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    Bullets n Babes DVDs HT Pics
     
  11. rigman

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    Jentz.

    was the person who has recalibrated your projector the same person who installed it?
    From what I have seen you have not had the projector that long so why was there a need to get it recalibrated. Is it the case that all CRT's need to be recalibrated every few months? Have you really got 1300 DVD's?

    thanks
     
  12. Jenz

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    Cossie0,

    Ahem why recalibration? Basically I ballsed up one of the settings. I was advised in another forum (not this one) that my dTV problem was related to the refresh rate I had set - 75hz.

    I was advised to drop it to 72hz. So I thought "Well my Barco would remember the config for the 75hz and save this new one as well". Turns out that the Barco 708 cannot really distinguish between the 72hz and 75hz because it relies more on Horizontal Refresh rate (which is almist identical at around 32hz). So I mistakenly wiped out by initial Engineer Installed setting [​IMG]

    I set it up myself as a result and whilst it looked good I knew it was not as good as before. So he very kindly dropped in and reset it. Suffice to say that he made sure I had settings configured for 640x480, 800x600, and 1024x768. He also showed me how the Memory Management worked so that it wont happen again [​IMG]

    As for regular calibration - No CRTs installed properly dont require it, this was a case of Tweaker Kill.

    As for 1300 DVDs, well sometimes it fluctuates above sometimes below. Its about that at the mo' but I have around 20 to trade on.

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  13. Ludae

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    Try Toy Story 2 where Woody finds out he was part of the 'Woody's Roundup' gang. This is a high contrast scene with lots of pan and tilt camera motion. Watch as the camera pans around the toy merchandise such as the printed plates. Do you notice any judder or blur? A bit like you're seeing two frames slightly overlaping as the camera moves. Or is the motion super smooth?

    This judder/blur, which you may not be particularly sensitive to, will exist due to frame repeating whether it be 3:2, 2:2, 3:3.

    The irregular nature of the 3:2 sequence will be worst of all and is best removed, but switching to 72 or 75Hz will not solve all the judder/blur problems.
     
  14. HT Dude

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    Doesn't for me, David. At 72 Hz, I still get slight judder in horizontal pans. They tend to come in pairs every second(ish).
    I'm putting it down to lack of processing power. But I'm far from convinced.
     

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