This must have been a consistent problem with iDVD for many years. I have found postings in various Mac forums dated as back as 2003 (!) referring to the cryptic "multiplexing error" that pops up at the very end of a very lengthy process.
I am using a new MacBook Pro 2.53GHz, 4 GB RAM, Mac OS X 10.5.6 (w/latest update) with over 200GB of free disk space.
I have spent several weeks trying to burn (actually, create a disc image for) a single DVD - just under 2 hours of video and slides - with the "Professional Quality" setting in iDVD 7. The movies play fine in Final Cut Express 4 where I edited them, in QuickTime, as well as in the iDVD preview. I need to fit just over 100 min on a single DVD (about 4.1GB total) so the "Best Performance" option is not really an option for me. I need the best possible quality. Both project and global iDVD settings specify "Professional Quality", NTSC, 16:9. No errors or warnings when launching "Save as Disc Image" or "Burn". It takes iDVD about 4 hours to encode all the assets. No warnings on the way. As soon as the "Burn" stage starts, iDVD produces a "Multiplexing error." The help documentation says that the most common reason is missing or bad assets, but all the assets are there, and they all play and encode just fine. The explanation itself is somewhat ridiculous. If you are saying that a missing asset may cause such an error, wouldn't you want to check for the presence of all the necessary items before you launch and run the process for 4 hours?! I had tried wiping out the project, creating brand new ones from scratch in various configurations, re-arranging menus, etc. You name it. It worked once - when I included a single 10-minute movie in the root menu, one slide show, and nothing else. However, iDVD failed to create disc images or burn any configuration of my real project. I called Apple support, they couldn't advise anything other than rebuilding the project from scratch... In other words, after all these years of people struggling with this very issue - regardless of the iDVD version - Apple still does not have a way to pin-point this very common bug. And it is nothing but a defect in their software! Good professional software should be catching any dangerous inconsistencies in the user project before it wastes half a day of the user's time. If an "unexpected" critical error occurs, good software should be capable of providing the diagnostics that would eliminate guesswork.
People have been searching for clues for years, and Apple seems to have dismissed the problem all together. I think it is extremely incompetent - and disrespectful to the customers - to keep releasing such half-baked software for years. You can't just dismiss such things as users- or hardware problems. If there is something with the user's project or the hardware that may prevent the software from creating a DVD then it should be up to the software to detect such conditions and report back what exactly the problem is. As far as I am concerned, iDVD is nothing but junk, cute-looking but unprofessionally written bloatware that Apple ships with their Macs. Shame!
I certainly don't mind paying for good software as long as it does the job. I have looked at iSkysoft's DVD Creator, downloaded the demo version, but it did not recognize my QuickTime .mov files that I had created in FCE. It did however directly ingest and burn .m2ts (AVCHD) files. I was not at all pleased with the image quality however. Can anyone recommend a reliable high-quality 3rd-party DVD-burning software for Mac OS that works with .mov files (e.g. files created in Final Cut and exported to QuickTime?)
Thanks for any help or advice!