Finished the Combustion render in full 1080p, and it looks pretty. It's a short clip, so I decided to see what I could do with some online HD streaming sites, namely Vimeo and YouTube. I did have to convert to a 720p h.264 encoding, but Vegas Pro is pretty damn fast with it using the Main Concept encoder (which kicks ass all over the Quicktime encoder BTW).
Ghostball from Rob Withoff on Vimeo.
The YouTube "high def" version is here. In theory, YouTube will eventually convert it to high-quality 720p, but so far it's disappointing.
Between the two, Vimeo has noticeably better quality. I haven't figured out yet how to get YouTube to give me the true 720p version; I suspect I may have to go to a 720p30 version, which really changes my workflow all over hell.
The original source is 1080i60. I can convert to either 1080p24 or 1080p30 pretty easily; 24 is preferred for "film" work and sourcing for broadcast and replication to DVD and blu-ray, but if the web is going to a 30p streaming format I pretty much have to decide where I'm gonna settle in that way.
Combustion doesn't seem to like 1080i60 files directly. I don't particularly either: compositing and effects with progressive frames is a hell of a lot easier.
I've been converting to 24p to emulate a higher-end camera source. Maybe it's not the way to go anymore.