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Native res LCD nonsense; DVI and black bars

Discussion in 'LCD & LED LCD TVs' started by jrecampbell, Sep 20, 2004.

  1. jrecampbell

    jrecampbell
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    This is my big sticking point on current LCDs - I've read that current screens like the Sharp Titaniums and the Philips 9986s, although true 16:9 1366x768, can't/won't utilise their full native screen resolution when fed a digital DVI or PC signal (and perhaps also other HD signals). I don't even know if I'm asking the right questions, but it's clear that there is some absurdity in whether manufacturers let you use all the pixels you've paid for in a given mode. I don't want to lose x% of my screen real estate because a display IDs itself as a lower res than it's actual res or has some odd syncing issue.

    I'm particularly interested in the Philips 37PF9986 but what I want, simply, is an LCD screen that will do the following:

    1. Be able to support digital output from a DVI-I-equipped DVD player showing a digital image using the screen's full native resolution without black bars around the picture.

    2. The ability to show full screen HD pictures in future without black bars. I've read in this forum for example that the DVI output from the pseudo-HD upscaling Samsung Hypervision 745/945 DVD would leave black bars showing on a current generation LCD screen in DVI mode. I am assuming that this is this because progressive HD is 1280x720p so a native vertical LCD res of 768 will leave 48 lines unused and horizontally leave 86, right? Can you force any LCD screen to use it's full resolution when viewing 720p content digitally (via DVI-I/HDMI)? And what would happen with 1080i?

    3. Utilise the full screen size pixel for pixel from a PC in the correct ratio. The Philips manual gives a maximum PC res of 1024x768@60Hz meaning either the ratio would be wrong for a 16:9 screen with 1366x768 res or there would be black bars each side of the image, right? Would Powerstrip be an option for this/any LCD TV?

    4. Ianh64 raised the issue of whether a panel could support native 50Hz or 60Hz at its native res. How does this have in impact day-to-day and how can it be found out before purchase? He also advocated the new Loewe Xelos screens. Are they really the only ones to achieve this flexibility?

    Another user wrote that LCD manufacturers should ideally ONLY use a res of 1280x720 or 1920x1080 to ensure that digital HD was always native full screen. Why they use 1366/1280x768 is a mystery to me given the future digital HD compromises this will necessitate. Please tell me if I've been worrying unnecessarily and if so where I can find my ideal screen!
     
  2. cerebros

    cerebros
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    Not quite sure why you have this fixation with having no black bars visible - you do realise that if you're watching a film with a ratio higher than 16:9 (i.e. something like 2.35:1 which is one the most common widescreen film ratios) you will get black bars unless you're zooming in on the picture and chopping the ends off it? And that's how it's supposed to be seen?

    And likewise if you're viewing material with a lower ratio (i.e. 4:3 which the vast majority of TV programs and very old films will be in) the only way to achieve full screen is by chopping off the top and bottom of the picture? And again you're getting rid of picture you're supposed to see?
     
  3. ianh64

    ianh64
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    I think there are three issues here:

    1. Can a LCD screen with panel resolution of 1366x768 take input at that resolution?

    I believe that the Loewe can, but until my DVD player can support 1366x768 output, I can not be 100% sure. The Sharp does, but only at 60Hz, ie not for PAL source. There is no documented or factual evidence that the Philips 9986 can.

    2. If you cannot supply at native 1366x768 resolution, can the screen scale the appropriate input to fit?

    I would imagine that this is possible for the majority of displays using the zoom or whatever feature. certainly the Loewe will take a 1280x768 input and scale to fit the whole screen, or scale width and slightly letterbox for 2.35:1 films (see below), or zoom into the picture cropping some of it but removing the letterboxing.

    3. If you play a non 16:9 DVD, can you scale it to fill the whole screen?

    As Cerebros says, you have to crop or stretch/distort it somehow to make it fit. Viewing a 1280x768 input in dot for dot mode on my 1366x768 screen, you can see the active picture area and the visible picture letterboxed within. The Loewe has a number of modes that allow it to be stretched, but in testing against LOTR, none would get a perfect (but distorted in aspect) fit on the 16:9 screen. Either it was zoomed and cropped, or zoomed and letterboxed. In non dot for dot mode, the same thing. However it seems better controlled by the DVD player/scaler settings than those on the display. Best I could get was full width and approx 5% cropped top and bottom.

    -Ian
     
  4. richard plumb

    richard plumb
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    and as for filling those extra few pixels top and bottom in 720p mode, I personally would prefer an exact 1280x720 picture, rather than add potential scaling artifacts. Especially when the scaling would be so small
     
  5. Bart A. S.

    Bart A. S.
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    Hi,

    if you haven't seen my post in another thread - it is possible to send both 1280*768 and 1368*768 signals via DVI to the 32pf9986. I tried it, and it worked - be it after a lot of tweeking with powerstrip. Most important setting in powerstrip is that the frequency is close to 60 Hz (+/- 1 Hz at most). All other settings may be varied over a fairly large range.

    Note however that although it does display a picture, there will always be black vertical bars of about 44 pixels wide, on both sides. The only way to get rid of these, is to use a *low* resolution: 640*480 or 800*600 do NOT show these black bars (?!).
    So, when using a 1280*768 signal via DVI, there is a (nearly) perfect match between signal and displayed pixels on your screen.

    Regards,
    Bart
     
  6. Toine

    Toine
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    found this for Nvidia cards :

    link

    maybe this creates some light in the darkness?
     
  7. Agent 86

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    One important factor which is being overlooked is that although the interfaces for high-definition sources will be either dvi or HDMI, they will have to support the hdcp copyright protection protocol. So even if you buy a high-definition lcd with HDMI interface, it will still need to support the HDCP protocol, which I don't believe any one does at the moment. Maybe this can be a firmware upgrade in the future, I don't know.

    Regards,
    Tim
     
  8. Toine

    Toine
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    in another post i saw that the philips pf9986 does. but this makes me not sure of it. You know more from this screen and hdcp?

    Regards,

    Toine
     
  9. Dutch

    Dutch
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    All HDMI interfaces support HDCP encryption - no firmware upgrades required. Hope this helps.

    Steve
     
  10. Agent 86

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    the

    Thanks for putting me right Dutch, apologies for my misleading information!

    Cheers,
    Tim.
     

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