PAL D1/DV Widescreen square pixel settings in After Effects (CS4 vs CS3)
Seems the latest version of After Effects from Adobe (CS4) has changed the PAL D1/DV Widescreen square pixel preset.
In CS3, compositions using that preset would be set to 1024 x 576 pixels. The new version (CS4) uses 1050 x 576.
So which is right? 1024 or 1050?
Well, to begin with, it’s all a bit complicated. I can still remember when it was first explained to me many years ago when I was still at the BBC, and it’s the kind of thing that’s quite difficult to get your head around without drawing little pictures on the back of envelopes. Anyway, there’s a few resources out there that try to explain this (links included below) – but I thought I’d have a go myself.
Oh, and before we get too bogged down, I’m talking about standard definition PAL here. The following explanation assumes 576 visible TV lines (out of the total of 625). So when I talk about aspect ratios and pixel dimensions the vertical height is always 576 regardless.
OK, here we go.
TV pixels aren’t square
A square pixel device (like a computer) would need an image to be 768×576 to maintain a 4×3 aspect ratio.
But TV pixels are rectangular – instead of 1×1, they’re more like 1×1.094.
So if we rewind a bit to the old analogue days – you can see from the diagram below that our TV set with its wider pixels is effectively only 702 pixels across.
television pixels aren't square
Here’s the crucial part – digital TV pictures are wider
The key to all this to remember that digital TV pictures are wider than analogue.
Digital TV pictures are 720 pixels wide.
But the 4×3 image (702 pixels wide) sits inside those 720 pixels.
There’s an extra 9 pixels each side.
digital TV pictures are wider than analogue - the 4x3 bit sits inside
The BBC guide to picture sizes says that these extra pixels are ‘required for digital processing’.
But, they might show up as black strips each side if the whole image is shrunk down via a DVE, or maybe these days if you are running your video in a window on a computer screen. I know that converting a 1024-wide movie from a Quicktime .mov to .mp4 format using Mpeg Streamclip does introduce black lines each side. Or at least it did for me the other day.
So if you’ve ever wondered ‘Why has my video got black strips each side?’ – this is probably why.
The reason for making your original After Effects composition wider is to guarantee that the whole image is filled with picture information. This will avoid either getting black lines each side, or having the application stretch the source material to fit, ending up with an image that’s ever so slightly distorted.
Adjustment for 4×3 compositions
For a 4×3 image that means your computer (square pixel) version would need to be 788 pixels wide.
Notice we now have allowed 10 extra (square) pixels each side on our source image. These equate to the 9 pixels (non-square) TV pixels we need.
To fill the entire (4x3) image area, build at 788 pixels wide
And the same is true for 16×9 widescreen images too.
16×9 widescreen adjustment
Remember that your original 16×9 image (1024×576 pixels) is only going to occupy the middle part of the TV screen. You still need to account for those extra pixels each side. Again, taking into account that the TV pixels aren’t square, this time we’ll need 13 (square) pixels on our source material to fill in the missing areas.
Widescreen composition should be 1050 pixels wide
So your original (square pixel) After Effects compostion needs to be 1024+13+13 pixels wide. Namely, 1050×576 to guarantee that it maps correctly on to the 720×576 digital output.
I don’t know whether Adobe, or makers of other applications were doing something clever behind the scenes to compensate in AE CS3 for 1024px projects to eliminate black edges. I suspect that what was really happening is that the end results when viewed on a real TV were just stretched very slightly, or any missing picture was hidden by overscan.
Anyway, it looks like Adobe have decided to use 1050 from now on.
And to be fair, nearly everyone I knew at the BBC was working to 1024. A few geeky designers like me tried to keep the 1050 flag flying, but as you can see, it’s not really the sort of thing anyone wants to keep explaining, especially if (like me) you don’t really understand it all in the first place.
Anyway. I hope that’s helped.
But, one last thing. I can remember MANY years ago doing a test at the BBC. I prepared two Photoshop images, each with a perfect circle in the centre of the screen. One was 1024 wide, the other 1050 wide. I scaled them both to 720 and laid them both off digitally and viewed them both on our broadcast-quality monitors. The 1050 one looked perfect, and the 1024 one looked very slightly distorted. Which is why I used 1050 for the BBC Weather animations a few years ago which featured a big glass circle fairly prominently.
Please feel free to comment here if you have anything useful to add. Worthwhile comments are ‘no-follow’-free!
Much love,
Mike
March 6th, 2009 at 9:02 pm
This is a great post. I encourage you to leave a comment on the page of After Effects Help that you link to above, linking back to this post. If you do, it’ll remind me to work the link into the main body of the document the next time that I update After Effects Help on the Web.
March 27th, 2009 at 8:31 pm
[...] After Effects CS4 – pixel aspect ratios – 1024 vs 1050 | Mike … [...]
March 31st, 2009 at 12:17 pm
Thanks for this, if Adobe have decided to make this change then why has photoshop not been updated with the new aspect ratios – it makes it very confusing as designers are designing to one standard and AE editors to another – come on Adobe sort it out.
April 20th, 2009 at 12:36 pm
I’ve been doing it wrong all these years! Great explaination. It’s seem that everyone is confussed about aspect ratios.
As 1050×576 isn’t 16:9 and Photoshop CS4 presets are still 1024×576 from a design point of view do I need to think about the extra 26 pixels? It seems to me that it’s just dead space that never gets seen?
April 21st, 2009 at 2:58 am
After many years we used to use 768×576 (wide and standard) they “discover” and illuminate us! Adobe, please allow us to make our own presets especially with our own aspect ratio!
April 27th, 2009 at 11:06 pm
Thanks Mike.
One note: I believe that your diagram entitled “television pixels aren’t square” is incorrect. Aren’t non-square TV pixels longer on the vertical side? You have the pixels looking wider in your diagram.
A video frame looks a bit too wide when viewing it on a PC, but when viewing it on a TV it skinnies up, therefore it seems as though the TV pixel would be taller.
I’m no expert, so can you tell me if this is correct?
Thanks!
Jim
April 27th, 2009 at 11:51 pm
Jim,
Thanks for the comment.
Possibly a PAL vs NTSC thing? I have a hunch NTSC footage gets squashed/stretched the other way from PAL.
Just checked – Adobe give pixel aspect ratios of 0.91 for D1/DV NTSC and 1.09 for D1/DV PAL.
Might that be it?
Mike
April 28th, 2009 at 12:56 am
That sounds like it’d be it! SO a PAL pixel is WIDE, whereas an NTSC pixel is TALL!
Learn something new every day…
Thanks!
Jim
June 22nd, 2009 at 5:22 pm
Thanks for the explanation; the BBC “Commissioning – A Guide to Picture Size” web page also confirms that many of us have been doing it wrong for a long time.
But this begs the question – does this mean that the 1920×1080 square pixels for HDTV is also wrong by 18 pixels?
Jeff
July 8th, 2009 at 12:27 pm
It is a real shame that it is now so complicated, as 1050 x 576 square pixels does not have an aspect ration of 16:9 !
Boaz
August 18th, 2009 at 11:39 am
Thanks for this post – very well explained. cheers, Axel
August 25th, 2009 at 4:13 am
[...] Afford has put together a good explanation on his website. Mike used to work for the BBC, but to get a direct statement from the BBC, you should check out [...]
August 25th, 2009 at 10:17 am
Very useful post, thank you.
September 19th, 2009 at 10:41 pm
I’m not sure my problem qualifies as a “square pixel”. Once or twice a week I have 1, 2 or 3 black rectangles about 1″ wide and 1 1/2″ tall. I have a 37″ 2 year old LCD Vizio TV. Any suggestions?
December 16th, 2009 at 10:26 am
Hi Mike,
Thanks a lot for taking the time to explain this! I just switched to CS4 and the new sizes were driving me crazy to say the least. Now i know why wich will make me sleep a lot better.
So again thanks for this!!
Kind regards,
Eddie
NL
January 19th, 2010 at 12:12 pm
Hi Mike,
We just switched back from Adobe Premiere CS4 to Avid Media Composer again. When still working With Premiere, we worked with “1050″ as it was compatible with After Effects CS4. (It all made sense when I first heard about it and now even more with your post…).
I’m curious though, how many other editing suites work with “1050″? I know Avid doesn’t… Will it be an industry standard or does the flatscreen (HD) TV-market have anything to do with it? We Use PS CS4 and AE CS4 and Avid. I guess we just have to work with
“1024″ again… What would you recommend?
Grtz,
Owen
January 30th, 2010 at 5:28 pm
Hi Owen,
I tend to build everything using 1050 now, but you’re right, some editing suites really don’t know what to make of it. (I came across the Avid issue while still at the BBC – but don’t know of others of the top of my head).
I would hope 1050 becomes industry standard eventually as it does lead to the best (i.e. non-distorted) results.
My suggestion is still to build at 1050 in After Effects (and thus any Photoshop material also at 1050) – that way you still have the option of dropping the whole thing into a new 1024 comp before the final render. It’s a bit of a cop out, but at least then if you need the extra pixels, you have them.
Or render at 1050 and use a quick After Effects comp to crop to 1024 only if the edit suite can’t handle it.
Sorry, but that’s the best I can suggest!
thanks for posting,
Mike