VLC and Quicktime Screen Sizes...

Discussion in 'Digital Video' started by Millwood, Sep 21, 2007.

  1. Millwood macrumors regular

    Joined:
    Jul 15, 2006
    Location:
    NY/NY
    #1
    I'm watching the same movie in VLC and in Quicktime. The movie is 720x576 in resolution. For some reason, when I open it in VLC it gives me a nice wide screen, but in Quicktime, it gives me a short fat screen. Does anyone know why the big difference in window sizes? Shouldn't they be both the same?
    here are examples: (quicktime is on the left, VLC on the right)
    If you can give me some help regarding why they are so different and what I can do to fix them I would appreciate it. I chose the 720x576 resolution because when it was in .vob format (ripped from a dvd) that was the native resolution, so when I encoded it to .avi I kept it the same.
     

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  2. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #3
    Because people don't always follow links when that's all the message has, I'll give you the brief description.

    The movie you are watching is in what is called "anamorphic widescreen" mode. This means that the movie is meant to be viewed in a wide ratio, but to get the maximum detail out of it, it is encoded at the maximum resolution of standard-ratio NTSC. This means that when viewed with square pixels, the video appears 'squished' like in QuickTime. This is because QuickTime is showing the video with a one-to-one mapping of pixels. That is how the movie is actually encoded.

    VLC, on the other hand, can see the little "anamorphic" flag in the video file, so it stretches it out sideways. It is actually adding 'width' data that isn't truly encoded in the video to do this, but it makes it look 'correct'. (The other option is removing 'height' data.)

    Many older widescreen TVs did not have square pixels. They had pixels that were wider than they were tall for this very purpose. When you do a one-to-one pixel map, the wider pixels make the picture look 'correct'. A common resolution for plasma screens was 1024x1024. So if the pixels were square (the way they are on a computer screen,) then the screen itself should be square. But it's not, it's much wider than it is tall. That means that effectively the picture is packing in more information 'up-down' than it is 'side-side'. Lots of high end standard-ratio CRT displays also re-jigger the electron guns so that instead of drawing square pixels covering the whole screen, they draw the same number of pixels, only they 'squish' them up-down so that they show a widescreen display in the center.

    Again, the advantage of doing this is that you get the full maximum resolution of the NTSC standard (720x576, which is *NOT* a 'widescreen' resolution,) and just stretch out the width (or squish the height,) to make the full detail become wide.
     

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