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.
XviD is the name of a popular new video codec being developed as an open source project by volunteer programmers from all over the world. The format was created to offer a free alternative to other commercial video codecs, and despite being open source its quality and efficiency has made it one of the most popular video codecs online.
XviD, as a file type, is an AVI file with video encoded with XviD codec.
To convert video to xvid, please make sure the xvid codec is installed.
GPL MPEG Decoder
AC-3 Decoder Filter
River Past Video Cleaner