Huge jump in file size after authoring.

[Ste]

I'm authoring a DVD5 with 21 titles and no menus. Each title has just 1 video stream and 1 audio stream. I calculated the average bitrate using the Java calculator on this website and encoded VBR using CCE. Before I begin authoring with DVDAuthorGUI, my audio and video files together take up 4.25 GB, but the VIDEO_TS folder I get after authoring has a size of 4.49 GB and Nero says that's too big for burning.
I guess my question would be: Does authoring add an extra 11.7 MB per title (see calculation below) as info about each title on the disc, or is something screwing up with the authoring process?
I don't remember this happening with any of my single title discs.

4.49GB - 4.25GB = 0.24GB
(0.24 GB * 1024 MB/GB) / 21 titles = 11.7 MB/Title

[johns0]

Authoring takes up that much so its best to keep the file sizes done to 4.15 gb or less depending on how many titles you use.

[borax]

Most of it is the "multiplex overhead" (info which video frame corresponds with which audio frame). For standard Audio (CBR; mp2 and most ac3) this may be roughly calculated like this:
Totalsize_in_MB = Videosize_in_MB + Audiosize_in_MB + (VideoDuration_in_seconds * 0.011)

[Ste]

Sweet. Thanks guys.