Why Are There So Many VOB Files When You Rip a DVD?
When users rip or explore a DVD's contents, they are likely to encounter multiple VOB files. This format is used publish media onto DVDs, and it contains all of the movie data that is stored on a disc. Although it is not used to distribute video over the Internet or onto hard disk, the VOB format is a variety of digitally compressed video just like MP4, FLV, MOV and WMV. In fact, some desktop media players can open the VOB files that are listed on a DVD and stream them just like any other digital video file.
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VOB File Format
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The VOB format is used to publish DVD object files. As a multimedia container, a VOB file can be composed of multiple data streams such as audio, text and graphics in addition to video. The audio and video tracks on a VOB file are typically published with MPEG-2 compression, an encoding standard that has been used for DVD authoring since its introduction in 1994. VOB files are essentially movie files that can consist of a series of DVD chapters. Therefore, DVDs with more chapters will have more VOB files.
DVD Ripping
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When a DVD is ripped, its media is copied to a hard disk. VOB files play a primary role in this process because it is their movie data that is being read and digitally encoded. There are numerous programs that facilitate DVD ripping, all of which are available in a wide range of prices and functionality. Many of these applications present users with a streamlined workflow for capturing DVD media, making it possible to isolate specific chapters and export the footage in a variety of digital video formats.
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VOB Conversion
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Because VOB files are basically a form of digitally compressed video, it is possible to bypass the use of DVD-ripping software by transcoding the files individually. A DVD's VOB files are normally stored within the disc's VIDEO_TS folder. Users can access this location by opening the file directory structure of the disc. When these files have been identified, they can be submitted to any file conversion application that accepts VOB as an input format. Once they are loaded into a compatible program, VOB files can be converted into more popular types of digital video such as MP4, MOV, WMV and FLV.
Copy Protection
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Most commercial DVDs on the market are copy-protected, which means that they are digitally encrypted to prevent unlawful distribution. Copy-protected DVDs are manufactured so that their source files cannot be accessed or copied. As a result, users cannot rip media from these DVDs or convert their VOB files into another format. While some extraction methods may be able to surmount copy protection measures, duplicating this type of DVD media is illegal and could potentially be considered copyright infringement.
Other DVD File Formats
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IFO and BUP files are generally listed alongside VOB files on DVDs. Like VOB, the IFO format digitizes information that enables DVDs to perform properly. But while VOB files contain actual media, IFO files contain playback data for DVD players and DVD-ROM drives. An IFO file consists of headers that initiate the welcome screen, signal the start and end points for chapters and indicate the location of audio tracks. DVDs will also contain BUP files, which are backup files of IFO files. BUP files are stored on discs in case the IFO files ever become corrupted.
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