IDVD create disk image larger than DVD-R capacity

Question

Here's the background:
- I made an iMovie 6 in 16:9 NTSC that is 1:32:00:06 long. I put that into iDVD 6, use the 5.0 Theme called "Wedding White", no slideshow, just a few photos and one 128k audio AAC file for menu music. Motion menu right now is about 5min45sec, but I can change that no problem.
- In iDVD 6's "Project info", left hand column shows "NTSC", "Widescreen (16:9)", "Best Quality", "Single-Layer (SL) - 4.2GB"; all correct.
Right hand column - Project Duration is 97:47min, Motion Menus is 5:46 of 7:30, Tracks 1 of 99, Menus 3 of 99; all green.
"DVD Capacity" was shown as ~3.3GB before the burning.
Here's the problem:
- When I first burned directly onto a single-layer DVD-R, an error will come on during burning or multiplexing near the end. Disc will eject, and the disc IS PLAYABLE on all DVD players. Only problem is that the movie will end (or says "Disc scratched or dirty", then crashes DVD Player on my Mac) at around 1:30:50; about 1min 11sec short. iDVD will also hang, and need to be forced quit.
- If I check that finished DVD-R with Disk Utility, it'll show:
--Capacity 4.4GB (4,706,074,624)
--Used 4.4GB (4,739,385,344)
- Same results with two decent media, a Sony 16x and a Ritex G05 8x.
- After reading a lot of posts in this discussion board, I tried two things:
1. Clean up my primary HD, which was down to <10GB free. I realized that I need double the disk space to properly burn. Now, it's at around 30GB free.
2. Instead of direct burn, I saved it as Disc Image. Results:
-- Video_TS file totally fine when played with DVD Player.
-- Disc Utility shows: Capacity 4,739,923,968 Bytes, Used 4,739,385,344 Bytes
But when I tried to burn that image onto a disc in Disk Utility, it says the media doesn't have enough room.
3. I went back to iDVD 6's "Project Info", and the "DVD Capacity" bar is now filled, yellow and says "4.2GB of 4.2GB".
[I actually tried earlier with a slightly different version with longer motion menus, and a slightly longer movie. And the DVD it tried to burn is even larger, at 4,847,159,296 Bytes. Similar results, but that DVD will end about 4 minutes short. But I didn't write down all the iDVD 6 details that time.]
SOOOOOO....
It seems to me that iDVD 6 is miscalculating its rendering or compression ratio, and is creating a final disc image larger than the capacity of a single-layer DVD-R, even though all parameters are set and displayed correctly.
For me, I'll cut down on the motion menu duration to see if that will help, as I'm right now JUST BARELY over the capacity.
Because of the early audio problem with iMovie/iDVD 6, this is the my first "finished" iDVD 6 product. Before, I have had no problem with movies that are close to the 120-minute limit, though this is the first time I use a 5.0 Theme with motion menus.
So, any ideas, any comments? Please post. Also, what else should I do besides posting here to let Apple and other users know of this problem? Thanks!
G4 Gigabit Ethernet Dual 1.6GHz Mac OS X (10.4.5) Pioneer DVR-110D, 1.12G RAM
G4 Gigabit Ethernet Dual 1.6GHz Mac OS X (10.4.5) Pioneer DVR-110D, 1.12G RAM

Answer 1

An update:
I cut down the loop duration of the motion menus, from 5:46 to 2:50. The resulting disc image is down to 4.25GB (4,563,716,096 bytes) and will fit onto a single-layer DVD-R.
So, I finally made my first successful DVD using iDVD 6. Still don't know why this has been such an adventure compared to earlier iLife versions.