questions about aspect ratios for dvd

Discussion in 'Amateur Video Production' started by Jeff, Dec 11, 2003.

  1. Jeff

    Jeff Guest

    I have a video clip I want to put on DVD. The resolution, for some
    reason, is 576x320 (1.80 aspect ratio).

    My question is, is it possible to resize that file to 720x480 with
    TMPGenc and author a DVD with a flag somewhere telling it that the
    ratio is 1.80? Maybe using something like IFO Edit?

    Or do I need to add letterbox bars to the clip, making it 576x432 (112
    of those vertical pixels being black bars), a 4:3 aspect ratio and
    then resizing to 720x480?

    Also, though I haven't had this issue yet, if I have a clip with an
    aspect ratio of 2.35, do I need to letterbox it before resizing to
    make it 1.85?

    Finally, why am I using 1.85 as my multiplier when 16:9 actually works
    out to 1.777?

    Thanks for any answers.
     
    Jeff, Dec 11, 2003
    #1
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  2. Jeff

    FlyByKnight Guest

    You need to letterbox it.
    Yes. This is standard on DVDs. Find any widescreen DVD that's in 2.35:1
    (Matrix Reloaded, for example) and play it on your computer software DVD
    player (Win DVD, Power DVD, etc.) Do not view in "full screen". View in a
    window.

    When the DVD starts, the player window will automatically resize to a 16:9
    window. Once the movie starts, you will be able to see black bars at the top
    and bottom. These are "hard-coded".

    DVD can be 4:3 or 16:9 only. Wider aspect ratios must be letterboxed.

    I have no idea. Get a 1.85:1 DVD ("Analyze This") and play as you did
    before. You'll see that even 1.85 is letterboxed (albeit slightly) to fit
    the 16:9 window.
     
    FlyByKnight, Dec 11, 2003
    #2
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  3. Jeff

    Jeff Guest

    Very odd. So why are DVD players set up for 16:9 if no movies are
    actually in that format, but are instead in 2.35 or 1.85? Why don't
    they support the two sizes movies are actually shot in, considering
    the players were designed specifically to play movies?

    Also, wouldn't it have made sense for them to allow any aspect ratio?
    How hard could it have been to have it just use some kind of tag to
    tell it how to resize the image?

    Excuse my ignorance, and thanks for the answers to my original
    questions.
     
    Jeff, Dec 11, 2003
    #3
  4. All movies are 16:9 (anamorphic widescreen) or 4:3 (letterbox
    widescreen or fullscreen).

    If you look at matrix reloaded for example, it has an aspect ratio
    of 2.35:1. That is, if you cut away the black bars and resize
    it properly (for playing on PC) you and up with 640x272 (or a
    scaling of this).

    For the resizing you only have to know whether the movie is 4:3
    or 16:9.

    Wilbert
     
    Wilbert Dijkhof, Dec 11, 2003
    #4
  5. Jeff

    FlyByKnight Guest

    You're asking me to explain why the relevant standards organizations do what
    they do? Since when did they have even a tenuous connection to logic or
    reality?

    The best answer I can give you (and it's really a chicken and egg thing) is
    this:

    DVD supports 16:9 because widescreen TV is 16:9. (Even pre-HDTV)

    Or... maybe widescreen tv is 16:9 because DVD supports 16:9. Who knows?

    I guess they figured they had to standardize on *something*...

    BTW... some movies *are* in 16:9 format. e.g. any movie recorded in HD "made
    for television"-type movie.

    Also, Star Wars Episode II (master) is in 16:9. Lucas cropped the top and
    bottom to 2.35:1 for a better cinematic experience (as, indeed, directors
    have been doing for decades - a 35mm film frame is, guess what? 4:3!)
     
    FlyByKnight, Dec 11, 2003
    #5
  6. Jeff

    Samuel Paik Guest

    16:9 was a compromise between 4:3 and the more extreme aspect ratios.
    Probably. Standard MPEG-2 supports 4:3, 16:9, 2.21:1, and arbitrary
    with "square pixels". However, high quality real-time video rate
    arbitrary scalers are expensive.

    Given how much the DVD people skimped on other parts, it's amazing
    we even got 4:3 and 16:9 support (anyone recall the Circuit City
    DivX? IIRC, that only supported 4:3).
     
    Samuel Paik, Dec 12, 2003
    #6
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