The extension VOB is derived from Video Object. These files are mainly found on DVDs.
The format is based on the MPEG Stream format, which has been adapted to the special requirements of a DVD. A VOB file is a special container that can contain multiple audio and video streams, subtitles, navigation, menus, and chapters.
A VOB file is part of a set called VTS, which contains more VOB files as well as ifo and bup files. The video data within a VOB file is always in MPEG II format, but the audio streams can be coded using different methods. The most common ones are ac3 and dts.
Virtually all commercial DVDs are protected by a Content Scramble System (CSS) copy protection process and are subject to various restrictions.
Unprotected VOB files can be played by many MPEG II enabled players. However, direct play causes only the simple video, audio stream to be played. Navigation, menus, etc. are not taken into account. For this you have to play the DVD or the corresponding directory.
Such VOB files can also be converted to another format.
The direct generation of VOB files is usually not possible and also pointless, since they are part of the structure of a DVD. Almost every video editing program is able to create DVDs and thus also VOB files and the associated structure.
Most often resolving problems with opening VOB files is very simple. Just install an appropriate program that supports such files. All of the listed programs support VOB files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of VOB files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate VOB files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Apple DVD Player applications is not on the list, select "Browse" option in order to manually locate the directory where Apple DVD Player has been installed.
Sometimes problems with opening VOB files may not lie with the application itself, but can arise due to other causes, such as: