How can quality be lost?

Let’s say I take a DVD-9 disk and I only want to keep the main movie file and the ac3 5.1 audio and use DVD2ONE to make it, how can quality be lost? Wouldn’t the bitrate and filesize be the same as it would be on the original disc? I can understand that by keeping everything in the DVD-9 disc and compress it to fit it on a DVD-5, of course there will be a quality loss to fit it into a smaller disc. What if I just want to take the “main” movie file and just keep it and dump all the extras. Will quality be lost? I keep on hearing that it’ll be transcoded and etc.

Originally posted by Sgt_Strider
What if I just want to take the “main” movie file and just keep it and dump all the extras. Will quality be lost?

Not if “movie only” is smaller than 4.7GB.

I keep on hearing that it’ll be transcoded and etc.

As far as I know DVD2one will only transcode if “movie only” is bigger then 4.7GB (well, there is logic).

On the same sort of topic…does it make any difference which compression mode is selected when doing movie only with a less than 4.7 gig film?

I know it’s not supposed to touch the video if it doesn’t have to, but thought the new options might have messed that up…

One would think that Con/Var choice would make no difference on 4.7 or less, and probably minor difference on 4.3-5.5 or so…
But I wouldn’t mind further details from authors.
I did appreciate the stuff now on dvd2one.com site, but when they have the time, I’d really like to read considerable technical details for the choices developers made in engines, how they effect output, and plans for further tweaking. If they are like me at all, they shouldn’t mind ‘rambling on’ with details on this field of obviously-shared interest, and showing off their considerable skills/research/speculation. [nothing proprietary, just informative…]

I think the authors would admit that there are better tools out there if you rip the main movie to you hard disk and it’s small enough to fit on one disc.

DVD2ONE comes into it element when the movie is larger than a DVD5 Disc or you want to put a DVD9 onto DVD5.

Just to say a BIG UP to the authors you have created a truly brilliant tool!!

Originally posted by billythehamster
I think the authors would admit that there are better tools out there if you rip the main movie to you hard disk and it’s small enough to fit on one disc.

I tend to just use D2O (regardless of size) for movie-only. I can readily cut the stuff I don’t want, and ending with a smaller-than-4.3 copy is just ‘insurance’…

AnyDVD coupled with D2O might be fun, though:

http://www.nickles.de/c/s/c/5-0015-317-2.htm

Wonder if it’ll work?