DVD2oneX & DVDRemaster / How do they work?

[twosocks]

I'm curious as to how these type of programs work. I've looked at the before and after information on select VOB files and the bitrate seems to be unchanged. How is it that they can reduce a 7GB movie down to less than 4.5GB without changing the bitrate?

Is this similar to the difference between an AIF file and a MP3?

[galactica]

If i remember correctly it has to do with dropping frames...
If you choose CONSTANT the bittrate shoudl be different, as it is heald constant