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Thread: 720x576

  1. #1

    Default 720x576

    I made a video in widescreen DV with a Sony HDR-FX1E. It filled the preview screen completely. The screen is 16:9, and I assumed widescreen is 16:9.

    So, basically, all signs say it's 16:9. But when I calculate the PAR manually: 720/576 = 1.25

    16/9 = 1.77

    How can this be correct?

  2. #2

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    You have not taken into account the Pixel Aspect Ratio - you have assumed the pixels are square, when for PAL they are not as it is grounded in CRT technology which used pixels wider than they are tall due to the way a CRT scans horizontally.

    For example, PAL is 720x576 (4:3) with a PAR of 1.067

    720/4*3 = 540

    720/4*3 * 1.067 = 576.18 (Not sure about the .18, maybe I did the math wrong, but I am pretty sure this is your answer)
    Last edited by evilc; 05-15-2008 at 07:02 PM.

  3. #3

    Default

    I think I recorded in 16:9, is it still possible to get this 720x576 resolution with that? Or did I do something wrong.

    Anyhow, thanks for your reply!

  4. #4

    Default

    Quote Originally Posted by KrisVR View Post
    I think I recorded in 16:9, is it still possible to get this 720x576 resolution with that? Or did I do something wrong.

    Anyhow, thanks for your reply!
    If it was recorded in 16:9, no there is no way to change this to 4:3 without cropping, letterboxing or deforming the image (which will result in things being the wrong shape).

    Cropping or letterboxing will be your best options. Probably cropping as you would still get full screen but you would lose a bit on the left and right. You could move the viewport around though if there was something in the cropped bit that needed to be seen.

    Howver I would not do this - I would just render it out at 16:9. If it is viewed on a TV, it would likely just show ithe middle and chop off the edges or letterbox it, depending on the TV. (Think about what happens when you watch a film on a 4:3 TV that is broadcast widescreen)

  5. #5

    Default

    Thanks for your reply.

    I don't want to convert to 4:3, I want to stay in 16:9. But I rendered my video and it was 720x576. So I rendered wrong? There's no way 720x576 can be 16:9? (Sorry for sounding/being stupid)

  6. #6

    Default

    4:3 or 16:9 specify the ratio of X to Y.

    Common 4:3 resoltions are 320x240, 640x480, 1024x768 for square pixels (This is why computers have these as options for desktop resolution) and 720x576 for PAL aspect ratio (1.067) pixels.

    In order for 720x576 to be widescreen 16:9...

    720/16= 45 * 9 = 405

    so 720 wide @ 16:9 res is 405 high.

    In order to force that to 576 height...

    576/405 = 1.422

    So you would need a pixel aspect ratio of 1.422 to make it happen.
    In other words if a pixel was 1mm high it would have to be 1.422mm wide

    Confirmation: 720 / 16 * 9 * 1.422 = ~576

    However, no display devices in existance have a Pixel Aspect Ratio of 1.422, so anything you displayed it on would have to interpolate the image which would result in quality loss.

    Not sure how the hell you rendered 16:9 to 720x576... Maybe it resized the frames? Does everything look tall and thin?

  7. #7

    Default

    Stop the press... I was wrong about no displays being 1.422 I think.

    I just looked in Premiere and PAL widescreen is indeed 720x576 with a pixel aspect ratio of 1.422

    Seems like my math was spot on though

    So it seems like yes, all is good, you just need to bear in mind the pixel aspect ratio for PAL widescreen is 1.422

    Sorry, never used widescreen SD before, wasn't aware that they just adjusted the pixel aspect ratio not the resolution.

  8. #8
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    Default

    Hi, I have a similar problem so thought it would be best to post here...

    I also have a Sony FX1... I uploaded the footage to a PAL Widescreen 16:9 project in Adobe Premiere and exported the movie to file, making sure that everything was set to widescreen 16:9.

    But when the file was finished, it plays in 4:3. It says the aspect ratio is 720x576 which you are saying is widescreen but it is showing up as a 4:3 video.

    Any ideas what is happening?

    PS, yes, I'm a newb

  9. #9
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    Default

    This thread reminsds me I shoot in 4 3 camera and stick to 4 3 when i edit - lols.

  10. #10

    Default

    Your PAL DV camera has a resolution of 720x576 and that is 4:3.

    When you turn on the Widescreen function it will put black bars at the top and bottom within the 720x576 resolution.


    Quote Originally Posted by evilc View Post
    4:3 or 16:9 specify the ratio of X to Y.
    In order for 720x576 to be widescreen 16:9...

    720/16= 45 * 9 = 405

    so 720 wide @ 16:9 res is 405 high.
    I think that's right. The widescreen viewable resolution is 720x405 within that 720x576.

    Hi, I'm new here. lol.

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