Note : This post has turned out to be a long one, so go make a cup of coffee, sit back and have a read through. The CS4 suite has been out for a good while now, so some of you may have noticed this already and researched the reason for yourself, but I never really thought much of it before (I still use AE CS3 for many of my projects for compatibility reasons, so it's not really been a concern). But, now I got curious and came across a blog posting I thought might make for interesting reading, and it explains the reasons for what I'm about to mention far more adequately than I could've done.
If you've used Adobe After Effects in the past to produce PAL format SD Widescreen productions, projects that may be used on the web as well as burned out to DVD, you may have done as I often do myself.
That is to create the project in After Effects with compositions using the "PAL D1/DV Widescreen Square Pixel" preset. In AE CS2 & CS3 (and probably earlier), that format has always come up as 1024x576, a perfectly respectable 16:9 ratio. Then nest that inside a "PAL D1/DV Widescreen" composition, right click, choose "Transform" then "Fit to Comp" (or ALT+Ctrl+F). That way, you can render out the square pixel composition with your fancy h.264 codec for the web and render out the non-square pixel composition using MPG2 for DVD usage, while retaining (imho) the maximum quality for both formats.
Well, thanks to CS4, it turns out we've been doing it wrong all this time. :)
When you create a "PAL D1/DV Widescreen Square Pixel" composition in AE CS4, the actual dimensions are now 1050x576.
"What? What is this madness? That's not 16:9!" I hear you cry.
Well, rather than try to explain it here without reproducing a lot of information in the post I'm about to link, I'll just link the post.
Now that it's all been explained, 1050x576 makes complete sense and we really have been doing it wrong all this time.
As mentioned earlier, I've always right clicked the nested square pixel comp and set it to fit perfectly inside the 720x576 non-square pixel composition to burn out for DVD, but this doesn't entirely fix the problem. It will make that square pixel comp fit the entire frame, thereby solving the problem of vertical black bars on either side of the footage, but as there are 13 pixels missing from either side of the square pixel composition it does stretch it just very slightly when played back from DVD. This may not be immediately noticable, but it is there and the camera already adds enough pounds as it is, or so they say, without making your actors even wider.
So, what does this really mean? As far as my personal workflow goes, it just means that I'll now be creating three compositions instead of two.
- Master Composition : 1050x576 PAL D1/DV Widescreen Square Pixel
- Web Composition : 1024x576 Square Pixels (exactly the same as the CS3 WS Square preset)
- DVD Composition : 720x576 PAL D1/DV Widescreen
This Master will then be nested inside the "Web Composition". This is a true 16:9 format composition which can then be uploaded to Youtube, Vimeo, hosted on your own website or wherever. The left and right edges of our frames will be cropped by 13 pixels each, which isn't really a problem if you obey the "Action Safe" guidelines.
The Master is also nested inside our 3rd compostion, the "DVD Composition". This is 720x576 pixels, so it's already set appropriately (remember, without the little extra on the side, it's actually 702 pixels wide, so this width has always been correct in past versions of AE, as far as I know).
And that's pretty much that, for now, although below are a few links with some more information about pixel aspect ratios and accurate dimensions when working on SD projects (HD projects aren't affected directly, but they are if you intend to ultimately go out to DVD or SD broadcast).
- AE CS4 Pixel aspect ratio and frame aspect ratio @ Adobe.com
- Commissioning - A Guide to Picture Size @ The BBC
A big thank you to Mike Afford for the enlightening information.
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