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Help me understand my plasma TV 16:9 aspect stuff

Discussion in 'Tech Talk' started by Genso, Dec 18, 2006.

  1. Genso

    Genso Millennium Member

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    I need help understanding different aspects - when they occur, what is standard, etc.

    I've been irritated because sometimes when I view a widescreen DVD I still get black bars on the top and bottom. Isn't this TV a widescreen already? If I switch from "Full" aspect to "Just", it stays the same. If I switch to "4:3", its obviously wrong and squished. "Zoom" might get rid of the bars on top and bottom, but then obviously the picture is cutoff from the sides (can't see half the name when the credits scroll by, etc). What is the deal? I note that I can fully tweak zoom and stuff in the DVD player's extensive menu. But there is never a perfect setting??

    Setup: I've been the happy owner of a Panasonic 42" plasma (TH-42PD50U) EDTV for about 1.5 years now. I have a matching Panasonic DVD player connected via HDMI.
     
  2. Genso

    Genso Millennium Member

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    As an example, right now I am watching Miami Vice Unrated Director's cut. Got the black bars on top/bottom when in "Full" or "Just" mode without any zoom applied.
     

  3. pesticidal

    pesticidal Eh? CLM

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    Don't have an answer for ya, just wanted to keep track of this thread....
     
  4. blue0623

    blue0623 2B1ASK1

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    The only thing I can think of with out talking to you more is that your dvd player is probally not hooked up to a HD input on your tv. If it is not the TV is not going to be able to tell you want wide screen and the Zoom most of the time will do nothing but distort the picture, 16:9 is only meant for HD output. If you need to know more let me know and I'll try to help. (I was a tech for 6 years so I dealt with HD alot)

    P.S. Just incase you don't know the HD input on the TV will be labeled with 1080i
     
  5. HAVOC

    HAVOC Remember CLM Millennium Member

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    Basically, most movies are shot in an aspect ratio wider than 16x9 (1.78:1). While you have the letterbox bars on top and bottom, they are significantly narrower than the ones on a conventional 4:3 (1.33:1) screen. Movies are commonly shot on film with a 2.4:1 aspect ratio (12x5, more or less). 16x9 is a bit of a compromise. With all the 4:3 TV footage out there, a cinematic aspect ratio screen would have huge black bars down the sides, while eliminating the letter box altogether on full blown movies.

    http://www.panavision.com/aspect_ratio.php
     
  6. 3/325

    3/325 Infidel Artist

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    There are a variety of aspect ratios used for shooting movies (and now tv shows as well). The only way to get rid of the letterbox bars along the top and bottom for all formats would be to buy a television where the screen width is 3x the height (they don't make 'em that way) and then you would end up with black vertical bars going up the sides of your picture.

    2.85:1, 2.35:1, 1.85:1, 1.66:1, 1.5:1, 1.33:1 ... these are just some of the possible aspect ratios used for film/tv. In order to make any of these match a 16:9 aspect there has to be some degree of squishing or stretching or clipping.

    [​IMG]
     
  7. Genso

    Genso Millennium Member

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    Thanks guys. These explanations (especially 3/325's graphic) are enlightening. At least now I know I am not screwing something up configuration-wise. Now it makes sense that some DVDs look "perfect" while others are letterboxed. Too bad filmers cannot agree to a standard that happens looks best on my TV =)


    Blue0623, I use an HDMI connection which supports HDTV resolutions.
     
  8. Toyman

    Toyman

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    Also, if your DVD player is an upconvert model, you might make it work by changing the output of the DVD PLAYER to something else. I can't test that right now because my LG Upconvert POS DVD player stopped working less than a year after buying it.

    edited to add: The output FORMAT of the DVD player, to something like 1080i, etc. NOT the output type (HDMI, RCA, ETC).
     
  9. Genso

    Genso Millennium Member

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    AFAIK, my EDTV is 480p, and DVDs are natively 480p. So in that respect, for my individual situation, things are pretty straightforward.
    I think most plasma owners however have HDTV, in which case they should certainly consider your advice.
     
  10. Darkmage

    Darkmage

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    True, but there is something else to consider.

    As you correctly noted, DVDs are stored as 480p (actually 720 x 480). Yet most movie DVDs show up as ratios that are not in the 4:3 ratio the DVD storage specification states. So what gives?

    There are a couple ways to handle this. First, the manufacturer can store the information that is taken up by the black bars you see top & bottom. At this point, you're spending valuable disk space to store an area of the screen that is never going to see any action. If you watch a widescreen movie on a 4:3 television and divide the screen up into 480 rows, you'll find that anywhere from 5 to 40% (approximately) of the rows are going to show nothing but black during your movie. It's inefficient to encode this area into the video stream, because nothing ever happens in it.

    The preferred method is use a technique that stores an anamorphic image that is then stretched appropriately by your TV. What this does is use the entire 4:3 ratio storage area on the DVD (the full 720 x 480 pixels) and then compress the video vertically at display time. If you recall the previous paragraph's 5-40% of wasted image, this technique uses that otherwise wasted area to store more information about the actual movie. Along with the 4:3 aspect ration video signal to your TV, your DVD player includes a tag that says "compress this image down to X.XX:1 ratio". The TV will add the necessary black bars by itself.

    You get the best of both worlds: you get a better image on your TV because your TV has more information to work with, and you don't have a signifant chunk of your DVD disk storing unchanging and boring video.

    This is a long-assed way of saying: "The fact that DVDs store data in 480p natively does not affect the quality of your *****in' 42" EDTV."