The rules list two proportions: 720x480 and 640x480. You could choose to use as much of that "canvas" as you want. Jeremy is right, the video sharing sites will letterbox a 16:9 submission. Regarding pixel dimension, use square pixels as this will be used for web and mobile content.
i am not, so take my opinion with a grain of salt. i do have a lot of experience dealing with pixel aspect ratio and the problems encountered. when it comes down to it, youtube (or alternative) is going to scale your video down to 320x240 anyway.
720x480 square pixels is not an existing ratio and a bad idea.
your best bet is to work at 720x540, square pixels.
before you submit via youtube/whatever, scale it to 640x480. if you need to put it on a dvd or other non square pixel format, you can then make it 720x480 (rectangular pixels) without losing quality.
The rules list two proportions: 720x480 and 640x480. You could choose to use as much of that "canvas" as you want. Jeremy is right, the video sharing sites will letterbox a 16:9 submission. Regarding pixel dimension, use square pixels as this will be used for web and mobile content.
i can't speak for the judges on if it is allowed, but if you submit 16x9, youtube(etc) will letterbox it.
Is it allowed to use 16:9 frame size? Or only 3:2 proportion is eligible?
i am not, so take my opinion with a grain of salt. i do have a lot of experience dealing with pixel aspect ratio and the problems encountered. when it comes down to it, youtube (or alternative) is going to scale your video down to 320x240 anyway.
Are you an official Cut and Paste person, Jeremy?
720x480 square pixels is not an existing ratio and a bad idea. your best bet is to work at 720x540, square pixels. before you submit via youtube/whatever, scale it to 640x480. if you need to put it on a dvd or other non square pixel format, you can then make it 720x480 (rectangular pixels) without losing quality.
So, just to clarify you don't want NTSC or PAL, you want a new thing?
Great questions. Square pixels would be best.