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  • Converting NTSC to PAL 16:9 Anamorphic

  • Jim McMahon

    April 27, 2009 at 10:44 pm

    OK, this seems like a very basic question, but I searched for it and have had no luck so far. Here we go:

    I am submitting a NTSC full-frame (4:3) spot to an awards show in France, and they are requiring that the spot be sent to them as a quicktime with the following specs:

    •720 x 576 anamorphic 16:9 – D1 PAL 25 fps.

    I double checked, and yes, they definitely want the clips anamorphically, so that they can just throw them all together, 16:9, 5:4 and 4:3, and play them all without any problems.

    OK, fine, but I’m very confused as to how to get the best image quality out of this process. As far as I can tell, my best bet is to stretch&squeeze the footage to 480×576, and then add black bars to the left and right.

    I came up with 480×576 in the following way:

    •Stretched the entire clip while maintaining NTSC aspect ratio, from 720×480 to 854×576.
    •Divided width (854px) by 1.78 (16:9), which equals 480px wide. This accounts for the 16×9 squeeze.
    •Maintained 576px as final height.
    •Final size is 480×854, but when unsqueezed on a 16:9 screen, the frame size will be 854×576.

    Here’s a big question:

    Does the PAL TV have the same type of non-square pixels as NTSC TVs? The strategy I have to maintain my aspect ratio rests on my assumption that PAL pixels are the same ratio as NTSC pixels.

    I feel that the above process is the best way to maintain my correct aspect ratio, assuming PAL TVs do have non-square (vertical) pixels.

    When I simply resize the image to PAL WITHOUT maintaining my aspect ratio, it makes the images skinnier. What I’m most worried about is that, once this image is played on a PAL TV, the images will be EVEN SKINNIER, to a point of being absurd.

    I tried resizing the image up to 720×576 while mantaining aspect ratio (crop), but then I’m losing the info on the sides. I’d rather that the image is a bit wider than normal to retain that info. After all, they ARE projecting it in 16×9, so that shouldn’t matter.

    Sorry for the long post. Thanks for the help!



  • Asmund Voll Tesdal

    May 2, 2009 at 12:30 am

    If I remember correctly, the aspect ratios of NTSC and PAL are not the same. I’m guessing they’re pretty close (and yes, PAL is also non-square), so I don’t know if you’ll actually be able to see the difference.

    [Jim McMahon] “•Divided width (854px) by 1.78 (16:9), which equals 480px wide. This accounts for the 16×9 squeeze.”

    Since the image is already 4:3, dividing by 1.78 is too much. If you have a PAL 4:3 image, dividing width by 1.33 (75%) should give a correct aspect for anamorphic.

    Also, I didn’t quite get what you mean here:

    [Jim McMahon] “•Final size is 480×854, but when unsqueezed on a 16:9 screen, the frame size will be 854×576.”

    When you say final size, do you mean the frame size of the final video? Unless I’m completely missing something, that needs to be 720×576.

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