Dvd backup and audio-tracks

Dear forum,
I tried to search this forum, the faq´s and so on, but didn’t really got any answer.
Its about the different audio tracks/streams on a DVD.
Take the calendar-girls. On the whole DVD (movie + extras) we got a bunch of audio-tracks, and I safely can get rid of al but 3:

[li]AC3 2 –ch Unspecified
[/li][li]AC3 5.1 –ch English
[/li][li]AC3 5.1 –ch Unspecified
[/li][/ol] Could someone please explain this for me? As I understand, could it have somethong to do with regions?

You only need to keep the 5.1 English track. But…make sure that there is actually something in this track. Look at the file size to see that it’s at least as big if not bigger than the other audio tracks. 5.1 English means it’s a “5.1 surround sound” track. 2-ch English means it’s your normal “2 channel audio”. Just keep the 5.1 English. It’s universal.

Thx dan_252 4 your quick answer…
An addition question:
I’ve notice that sometimes the movie and the extras have different soundtracks.
For example:
The main movie has

[li]AC3 2 –ch Unspecified
[/li][li]AC3 5.1 –ch Unspecified
[/li][li]AC3 5.1 –ch English[/ul] the extras[ul][/li][li]AC3 2 –ch Unspecified
[/li][/ul] Can I from the movie safely remove [ul][li]AC3 2 –ch Unspecified
[/li][li]AC3 5.1 –ch Unspecified
[/li][/ul] and still have sound in the extras?

The different audio tracks between the “main movie” and the “extras” is simply b/c when you’re talking about extras, you’re dealing with things such as director’s commentaries, deleted scenes, etc… these things do not normally use the 5.1 surround that is used in the main movie. So… you would normally just leave the 2-channel audio in the “extras”, but you can safely remove it in the “main movie”. Like I said earlier, though… just be sure that whatever audio track you are leaving, does contain something (check the file size). Hope this helps!

thanx again