Hi,
Tried looking for a solution but i dont think there is 100% full proof way of doing it.
I looked ard for an application to rip out AC3 audio but came up with none. The closest i came up with is a DVD to MP3 or wave ripper. Meaning that you get only stereo sound for one sound track.
(Check out DVD Audio Ripper at
http://www.imtoo.com/cd-ripper.html )
For Creating a multilingual DVD, i believe only the more expensive DVD authoring software (E.g Adobe Encore DVD is one of them) can do this. There is a guide you can check it out ..
http://www.adobe.com/tips/enc15multiling/main.html .
Problems are that the above ripped soundtrack could be out of sync if you should merge them together, the disk may be bigger and may not be able to store on one DVD-RW.
I dont have either of the software so i cannot try it out. Thus I dont know if this theroy will work.