DVD Video Oject or as it is better known VOB is the container file on a DVD Disc that contains the actual film data.
VOB files are MPEG-2 system streams that contain the MPEG-2 video stream and audio streams.
VOB files can contain the following compression formats.
» H.262/MPEG-2 Part2 video
» MPEG-1 Part 2 video
» MPEG-1 Audio Layer II audio
» MPEG-2 Audio Layer II audio
» Linear PCM
Normally the files on the DVD are made in to 1GB VOB files which keeps it inside the maximum sizes that are supported by various file systems.