VOB standards for "Video Object". It is the file type to store video on a DVD disc. It is actuallly a MPEG-2 video, with special extension to support PCM, AC3, DTS audio, subpictures, and button navigation commands.
To decode DVD-VIDEO, you will need both GPL MPEG-2 Decoder, and AC-3 Decoder.
A variant of the MPEG video and audio compression algorithm and file format, optimised for broadcast quality video. MPEG-2 was designed to transmit images using progressive coding at 4 Mbps or higher for use in broadcast digital TV and DVD. An MPEG-2 player can handle MPEG-1 data as well. MPEG-2 has been approved as International Standard IS-13818.
MPEG.ORG is an excellent source for additional information on MPEG format and usage.
To encode MPEG-2 video, you will need River Past MPEG-2 Booster Pack in addition to your video software.
GPL MPEG Decoder
AC-3 Decoder Filter
River Past Video Cleaner