I think he meant the video quality of a compressed disc and an original.
If you got the space (size on the disc), then go for the DTS. It's proven that it's better but it takes up a huge amount of disc space which is why many people (including I) refrain from including it.
Latest AnyDVD to rip > VOBB to blank the unwanted on a DVD > Shrink to compress > ImgBurn to burn = Never starting a thread asking how to backup a movie
You will only notice the difference on a normal tv with films that need alot of compression like King Kong, LOTR etc...etc... But if you have a 52" HDTV like me you wil notice the difference with compression levels of around 75%. (when using transcoders)
I only use Recode2 with compression levels of upto 80% (20%) anything below that I use DVD-RB Pro with Procoder 2. The results are 1st class.
I never include DTS. Not because it's not good, but if I ever decided to use the backup at a friends house that can't play DTS the film would have no sound. Since I own the originals, it's no big deal to get the disc out if DTS is required, but IMO it makes no sense to include it on a compressed single layer backup.
I always keep both the DTS 5.1 (if available) and AC3 audio tracks. Granted the DTS track takes up more space on the disc than the AC3 5.1 (about double) but in relationship to the amount of disc space used for video, the DTS sountrack is small and I am aware that you can not compress the audio tracks. Sure a little more video compression is required but that's why I use RB/CCE.
On the other hand, if you do not have a DTS surround system there would be no reason to keep the soundtrack. DTS is definately better than DD 5.1 but DD 5.1 is better than plain AC3 2 channel by far.
In order to appreciate DTS, you will need a higher quality sound system. A theater in a box setup will not give you the benefits of it.
Also, DTS will not work on normal TV speakers where Dolby Digital 5.1 will convert itself to DD 2.0 when played on a TV with no surround sound setup. This is the biggest benefit of Dobly Digital.
So, basically, the backup should have the highest compatibility. This means that if you have to choose between Dolby Digital 5.1 and DTS, always go for Dolby 5.1. If you can fit both, then go for both. Backups are great for trips, so you want to be able to watch them on a portable player. With DTS only, you will not get any audio.
The rule of thumb to follow is essentially this:
To guarantee playback, use Dolby Digital.
For best quality, use DTS.
Dolby Digital is a mandatory format for DVD-Video, and DTS is an optional one.
This means that all DVD players MUST be capable of decodeing a DD stream, but might not be capable of decoding a DTS stream.
Also, if using a PS2, remember that it cannot automatically switch between DD and DTS - you must reset the optical audio option each time.
