down-rezing / keying HDV footage
 

I'm an absolute newbie to HD/HDV and I have a couple of (hopefully) simple questions that I hoped someone here could help with.

I'm borrowing an HD100 for the weekend to shoot green screen footage of closeup of a person. The footage will be captured in Vegas and composited in After Effects with animated backgrounds. The final video will be mastered to DVD for a video art exhibition.

When I downrez to SD, should I do it in Vegas or in After Effects? Along with that, is it better to key it as HD, then down-rez to SD, or down-rez before keying? Or does it matter?

An even more basic question, if down-rezing is all done in After Effects, is it simply a matter of placing the HD clip into an SD composition and scaling it down? Is there a better method?

I would keep the entire After Effects project in HD and scale to SD just for the final disc, but unfortunately some of the background elements are coming from DV footage and will lose too much resolution scaling up.

Again, newbie questions. Hopefully someone has some answers (and patience).

Thanks.

If the quality is important, I would render an uncompressed TGA quicktime (or cineform) from vegas at the full 1280x720 (make sure the smart interpolation is off or Vegas may add motion blur to your footage that isn't really there).

I would then key it at 720p in after effects and then yes, scale it down when yer done (1 comp at 720, one at 480 or whatever your final res is), this gives you more data to work with, which, in theory should make for a better key (make sure you have a well lit green screen of course).