I had the pleasure to attend the John Logie Baird Lecture on The History of HDTV this week. The three speakers from Japan, USA and German explained the progression of technology through the last century which has lead to the situation today with HDTV. The question of why we need more lines was answered in detail but to summarise, bigger screens need more lines to look as good as our existing pictures.
There was some great news as far as I was concerned, all three zones have agreed on a standard for HDTV. So when making new animations I only need to make them in one size...
This is true but not the whole picture (excuse the pun). There are in fact 2 sizes defined in the standard 720p and 1080i. Both of these have a standard aspect ratio of 16:9.
In addition multiple frame rates are defined by the standard, 24/30/60. The 24 is the frame rate used traditionally in film.
For the purposes of animation I don't need to be concerned with the interlacing but the progressive scan has shown to be better for sports coverage and quickly moving objects. One hardware engineer has recently shown that in some cases 1080p compresses better than 1080i so perhaps our future will be interlace free?
So where does this leave me for animations?
Wide screen formats are the imediate future and existing systems can happily manage with those images. So for my next film, I'm definitely going to be looking into making it in a 16:9 format but the actual rendered size will most likely be dependant on my hardware, possibly 540x960 at 30 frames would be a happy compromise.
More about HDTV http://hometheater.about.com/cs/beforeyoubuy/a/aahdtvfaqs2a.htm
Up converter 1080i to 1080p http://www.meridian-audio.com/faroudja/prod_dvp-1080.phtml
Down converter 1080i to 525i or 625i http://www.evertz.com/products/2410MD-HSN
The film resolution standard is 2048 x 1556 and the way they display it on the cinema screen is to crop the top and bottom of the image.