VideoHelp Forum

Try DVDFab and download streaming video, copy, convert or make Blu-rays,DVDs! Download free trial !
+ Reply to Thread
Results 1 to 8 of 8
  1. I make family DVDs for viewing on my widescreen TV. (I currently use Magix Movie Edit Pro 17 Plus for editing and menu authoring, and burn with ImgBurn.)

    It's probably aggravated by excessive googling, but I've got myself confused: what pixel size should I make an image (e.g a photo, or a diagram drawn in my image editor, etc), so that when I finally see it on my wide TV it will be 100% accurate. IOW, a perfect circle, not squashed to even a tiny degree?

    It appears from my research that an image of 1600 x 900 or 1024 x 576 or whatever (i.e. any with a 16:9 AR) will end up with slight distortion. Practical tests with a tape measure on my TV screen seem to confirm this. Not previously noticeable, but now I'm positively looking for it! Circles are slightly wider than they should be. People ever so slightly fatter, etc.

    Some of the material I read was confusing and inconsistent. Perhaps understandably, as IMO it's a complex issue when you explore it in depth. But the following was the essential bottom line, repeated in several apparently authoritative places:

    "For widescreen TV, to transfer computer generated images (square pixels) to video (rectangular pixels), you should create them at 1024 by 576 pixels, then resize them to 720 by 576."

    Is that correct? For DVD menus too? Does it matter whether I'm working in the editor at 1280 x 720 or 1920 x 1080? What are the practical implications? How much is typically done by the authoring program as against being left to the user? What steps must I take for the menu, even if I continue ignoring tiny imperfections in the main DVD?

    Any advice or insight would be much appreciated please.

    Terry, East Grinstead, UK
    Quote Quote  
  2. Always Watching guns1inger's Avatar
    Join Date
    Apr 2004
    Miskatonic U
    Search Comp PM
    If you are working in the editor with HD footage at 720p or 1080p then you should load your photos and frame them in the editor to fit within the existing frame. HD 720p or 1080p is square pixel, so you don't have to worry so much about the pixel shape. If you cannot resize the images inside your editor, then you can resize them in an image editor first. I would suggest opening a new image at the correct size (1280 x 720 or 1920 x 1080), then loading your image onto a new layer and scaling/framing it to best fit inside the appropriate size. Simply resizing the image, unless by chance it is already 16:9, will cause distortion.

    Even if you are working with widescreen material at SD resolution, your editor should be presenting the material unsquashed, and so you should be able to put images on the timeline without prior resizing, and allow the editor to deal with the resizing when it encodes.
    Read my blog here.
    Quote Quote  
  3. Thanks guns1inger. I'll try and get my head around that and experiment along the lines you suggest.

    Any thoughts re my question on the very slight distortion I measured? Can you and others confirm that is real, when using standard procedures? And that it would need careful cropping and resizing to remove it?

    Since my original post, I've been reading this article:
    which has my head spinning!

    Terry, East Grinstead, UK
    Quote Quote  
  4. The DVD spec refers to the MPEG 2 spec regarding aspect ratios. The MPEG 2 spec is very clear: the entire frame comprises the aspect ratio, 4:3 or 16:9. That means the entire 720x480 or 720x576 frame is the 16:9 picture. This is at odds with the ITU spec which defines the ~704x480 or ~702x576 frame as the 4:3 or 16:9 picture with the rest of the frame for padding. Some professionally mastered discs seem to assume one, some the other. Even different outputs on DVD players handle it differently. In my experience the composite and s-video outputs follow the ITU spec, upscaled HDMI outputs follow the MPEG 2 spec.
    Last edited by jagabo; 15th Sep 2011 at 08:59.
    Quote Quote  
  5. Since you are in the UK, you may want to follow the BBC guidelines

    (or you might not care, since this is family stuff)

    They base their calculations on 702px width, so 16:9 square pixel equivalent would be 1050x576

    The actual BBC document is down, but I have a capture attached

    Jagabo is right however, there are many different ways of doing it , and even differences between equipment and various studios. So what might look perfect on your setup might be slightly different on your neighbor's setup

    Some people don't like 702px , because it's a non mod16 width. So they round up to 704px, pad 8px pillarbox.
    Image Attached Thumbnails BBC - Commissioning - A Guide to Picture Size.pdf  

    Last edited by poisondeathray; 15th Sep 2011 at 09:32.
    Quote Quote  
  6. You could avoid the problem (mostly) by using 704x480 or 704x576 frame sizes. Those are also legal for DVD.
    Quote Quote  
  7. Thanks all. Reckon I have some hard studying to do!

    Terry, East Grinstead, UK
    Quote Quote  
  8. That suggestion to encode with 704 x576 has resulted in much greater accuracy. Many thanks! Now only 1 to 1.5% distortion.

    However, why hasn't the menu responded as well? That is still 2.5 to 3% distorted (circles are fatter). How do I fix that please?

    BTW, why isn't 704x576 the 'norm', given its greater accuracy?

    Terry, UK
    Quote Quote  

Similar Threads