DVD content - VOB filetype

DVD
content is compressed according to DVD specifications so that it
plays reliably on a wide range of players. When preparing content
for a DVD project, pay attention to frame size and frame rate, so
that content retains its quality in the transition to DVD.
For best results, make sure that you capture or record according
to these specifications:

Frame sizeNTSC standard 720x480 or PAL standard 720x576. If your project uses
a different frame size, Adobe Premiere Pro scales it automatically.Frame rate29.97 fps (NTSC) or 25 fps (PAL); alternately, 23.976 (NTSC)
for 24p. All footage in a single project must be of the same frame
rate.Aspect ratio4:3 or 16:9 (widescreen).Audio bit depth16 bits.Audio sample rate48 kHz.

Citação :

You cannot import vob files directly into Adobe Premiere Pro CS3.
However, in some cases, if you change their vob file extensions to mpeg
extensions, you can import and edit the files. Also, you can import vob
files into Premiere Elements, and export the movie in a file format
supported by Adobe Premiere Pro.