I'v just rendered a 2 hour music video concert in V4 to mpeg2 at 24fps set the bit rate to 5.4 . The file rendered to 3.5gigs video, and 166.221K sound.
When I import these files into DVDA I'm getting a 7.9gig project. ????
DVDA isn't always very good at project size estimates. In additional, I know I've run into a situation where it pulled the same source movie in twice because of how I set up my menu.
Try doing a Prepare and see how large the resulting files actually are.
Since 7.9gig would be consistent with having your 3.5gig file included twice (i.e., 7gig alone), that’s the first thing I would look for. Make sure you didn’t add it twice by mistake.
This is a well-known bug in Vegas. It usually happens if you try to add a submenu. Remove all submenus and try again. Also, try starting a new project, import the movie, and then immediately go to the optimize menu. See if it reports the correct file size. If it does, rebuild the project, but keep saving to different file names every time you do something (file01, file02, etc.) so you don't have to rebuild everything when you hit the bug.
Also, the file size estimates in DVDA are completely unreleated to reality. However, as bad as they are, they won't give you estimates that are 2x reality. Therefore, I really believe that problem you are seeing is from the submenu bug.