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Analogous to MPEG-2 Program stream, VOB file can contain [[MPEG-2 Part 2]] or [[MPEG-1]] Part 2 video, [[MPEG-1 Audio Layer II]] or MPEG-2 Audio Layer II audio, but usage of these compression formats in VOB file has some restrictions in comparison to MPEG-2 Program stream. In addition, VOB can contain [[Linear PCM]], [[Dolby Digital|AC-3]] or [[Digital Theatre System|DTS]] audio and subpictures (subtitles).<ref name="mpeg-dvd" /><ref>MPEG.org (July 21, 1996) [http://www.mpeg.org/MPEG/DVD/Book_B/Video.html DVD Technical Notes - Video Data Specifications], Retrieved on 2009-07-25</ref><ref name="videohelp-dvd">Videohelp.com [http://www.videohelp.com/dvd#tech What is DVD? Technical Info for DVD-Video], Retrieved on 2009-07-28</ref> VOB file cannot contain [[Advanced audio coding|AAC]] audio (MPEG-2 Part 7), [[MPEG-4]] compression formats and others, which are allowed in MPEG-2 Program stream standard.<ref name="iso13818">ISO (2000-12-01) [http://neuron2.net/library/mpeg2/iso13818-1.pdf ISO/IEC 13818-1 : 2000, Second edition] (PDF), Retrieved on 2009-07-25</ref>
Analogous to MPEG-2 Program stream, VOB file can contain [[MPEG-2 Part 2]] or [[MPEG-1]] Part 2 video, [[MPEG-1 Audio Layer II]] or MPEG-2 Audio Layer II audio, but usage of these compression formats in VOB file has some restrictions in comparison to MPEG-2 Program stream. In addition, VOB can contain [[Linear PCM]], [[Dolby Digital|AC-3]] or [[Digital Theatre System|DTS]] audio and subpictures (subtitles).<ref name="mpeg-dvd" /><ref>MPEG.org (July 21, 1996) [http://www.mpeg.org/MPEG/DVD/Book_B/Video.html DVD Technical Notes - Video Data Specifications], Retrieved on 2009-07-25</ref><ref name="videohelp-dvd">Videohelp.com [http://www.videohelp.com/dvd#tech What is DVD? Technical Info for DVD-Video], Retrieved on 2009-07-28</ref> VOB file cannot contain [[Advanced audio coding|AAC]] audio (MPEG-2 Part 7), [[MPEG-4]] compression formats and others, which are allowed in MPEG-2 Program stream standard.<ref name="iso13818">ISO (2000-12-01) [http://neuron2.net/library/mpeg2/iso13818-1.pdf ISO/IEC 13818-1 : 2000, Second edition] (PDF), Retrieved on 2009-07-25</ref>


On the DVD, all the content for one title set ([[Video Title Set|VTS]]) is contiguous, but broken up into 1 [[Gigabyte|GB]] VOB files in the computer compatible file systems for the convenience of the various operating systems.<ref name="whatisvob" /> Each VOB file must be less than or equal to one GB (1024x1024x1024 [[Bytes]] = 1,073,741,824 Bytes).<ref>Doom9.org [http://www.doom9.org/dvd-structure.htm doom9.org What's on a DVD?], Retrieved on 2009-07-26</ref>
On the DVD, all the content for one title set ([[Video Title Set|VTS]]) is contiguous, but broken up into 1 [[Gigabyte|GiB]] VOB files in the computer compatible file systems for the convenience of the various operating systems.<ref name="whatisvob" /> Each VOB file must be less than or equal to one GiB.<ref>Doom9.org [http://www.doom9.org/dvd-structure.htm doom9.org What's on a DVD?], Retrieved on 2009-07-26</ref>


Other DVD files include [[IFO]] and [[BUP]] files. IFO (Info) files contain all the information a DVD player needs to know about a DVD so that the user can navigate and play all DVD content properly<ref>AfterDawn.com (2007-07-31) [http://www.afterdawn.com/guides/archive/how_to_play_vob___ifo___bup_files.cfm How to play VOB / IFO / BUP files], Retrieved on 2009-07-26</ref> (e.g., where a chapter starts, where a certain audio or subtitle stream is located, information about menu functions and navigation, etc.). BUP (Backup) files are an exact copy and backup of IFO files in case of corruption. VOB files without IFO or BUP files do not allow DVD menu navigation. Images, video and audio used in DVD menus are stored in VOB files.
Other DVD files include [[IFO]] and [[BUP]] files. IFO (Info) files contain all the information a DVD player needs to know about a DVD so that the user can navigate and play all DVD content properly<ref>AfterDawn.com (2007-07-31) [http://www.afterdawn.com/guides/archive/how_to_play_vob___ifo___bup_files.cfm How to play VOB / IFO / BUP files], Retrieved on 2009-07-26</ref> (e.g., where a chapter starts, where a certain audio or subtitle stream is located, information about menu functions and navigation, etc.). BUP (Backup) files are an exact copy and backup of IFO files in case of corruption. VOB files without IFO or BUP files do not allow DVD menu navigation. Images, video and audio used in DVD menus are stored in VOB files.

Revision as of 17:09, 23 October 2009

For Versioned Object Bases, see Rational ClearCase. For Voice over Broadband (VoB), see Voice over Internet Protocol.
VOB
Filename extension
.VOB
Internet media typevideo/dvd, video/mpeg, video/x-ms-vob
Developed byDVD Forum
Type of formatMedia container
Container forAudio, video, subtitles
Contained byDVD-Video
Extended fromMPEG-2 Program stream, ISO/IEC 13818-1
StandardDVD-Video Book[1][2]

A VOB file (Video Object) is a container format in DVD-Video media. VOB can contain video, audio, subtitle and menu contents multiplexed together into a stream form. VOB is based on MPEG-2 Program stream format, but with additional limitations and specifications in the private streams.[3] [4] The MPEG-2 Program stream has provisions for non-standard data (as used in VOB files) in the form of so-called private streams. VOB files are a very strict subset of the MPEG-2 Program stream standard. While all VOB files are MPEG-2 Program streams, not all MPEG-2 Program streams comply with the definition for a VOB file.[3]

Analogous to MPEG-2 Program stream, VOB file can contain MPEG-2 Part 2 or MPEG-1 Part 2 video, MPEG-1 Audio Layer II or MPEG-2 Audio Layer II audio, but usage of these compression formats in VOB file has some restrictions in comparison to MPEG-2 Program stream. In addition, VOB can contain Linear PCM, AC-3 or DTS audio and subpictures (subtitles).[4][5][6] VOB file cannot contain AAC audio (MPEG-2 Part 7), MPEG-4 compression formats and others, which are allowed in MPEG-2 Program stream standard.[7]

On the DVD, all the content for one title set (VTS) is contiguous, but broken up into 1 GiB VOB files in the computer compatible file systems for the convenience of the various operating systems.[3] Each VOB file must be less than or equal to one GiB.[8]

Other DVD files include IFO and BUP files. IFO (Info) files contain all the information a DVD player needs to know about a DVD so that the user can navigate and play all DVD content properly[9] (e.g., where a chapter starts, where a certain audio or subtitle stream is located, information about menu functions and navigation, etc.). BUP (Backup) files are an exact copy and backup of IFO files in case of corruption. VOB files without IFO or BUP files do not allow DVD menu navigation. Images, video and audio used in DVD menus are stored in VOB files.

Copy protection

Almost all commercially produced DVD-Video titles use some restriction or copy protection method, which also affects VOB files.[10] Copy protection is usually used for copyrighted content.

Many of DVD-Video titles are encrypted with Content Scramble System (CSS). This is a data encryption and communications authentication method designed to prevent copying video and audio data directly from the DVD-Video discs. Decryption and authentication keys needed for playing back encrypted VOB files are stored in the normally inaccessible lead-in area of the DVD disc and are used only by CSS decryption software (e.g., in a DVD player or software player). If someone is trying to copy the contents of an encrypted DVD-Video (e.g., VOB files) to a hard drive, an error can occur, because the DVD disc was not authenticated in the drive by CSS decryption software. Authentication of the disc allows the copying of individual VOB files without error, but the encryption keys will not be copied. If the copied undecrypted VOB files are opened in a player, they will request the keys from the DVD-ROM drive and will fail.[11][12] There is some CSS decrypting software, or ripping software, such as DeCSS, DVD Decrypter, AnyDVD or DVD Shrink which allow a protected DVD-Video disc to be copied to hard disk unscrambled. In some countries, their usage can be a violation of law (e.g. for non-personal use).[12]

Other DVD containers

Some DVD Recorders use DVD-VR format and store multiplexed audiovisual content in VRO containers.[13][14] VRO file is an equivalent to a collection of DVD-Video VOB files. If one doesn't care about any edits (e.g., deleting of recorded videos), one can play the VRO directly as if it was a standard DVD-Video VOB file.[15] Fragmented VRO files are not widely supported by software players and video editing software.[13]

Playback

A player of generic MPEG-2 files can usually play unencrypted VOB files, which contain MPEG-1 Audio Layer II audio. Other audio compression formats such as AC-3 or DTS are less supported.[citation needed]

ALLPlayer, MPlayer, VLC media player, Media Player Classic and more platform-specific players play VOB files.

See also

References

  1. ^ DVD FLLC (2009-02) DVD Book Construction - list of all available DVD Books, Retrieved on 2009-07-24
  2. ^ DVD FLLC DVD Format Book - History of Supplements for DVD Books, Retrieved on 2009-07-24
  3. ^ a b c What is a VOB file, Retrieved on 2009-07-26
  4. ^ a b DVD - MPeg differences, Retrieved on 2009-07-24
  5. ^ MPEG.org (July 21, 1996) DVD Technical Notes - Video Data Specifications, Retrieved on 2009-07-25
  6. ^ Videohelp.com What is DVD? Technical Info for DVD-Video, Retrieved on 2009-07-28
  7. ^ ISO (2000-12-01) ISO/IEC 13818-1 : 2000, Second edition (PDF), Retrieved on 2009-07-25
  8. ^ Doom9.org doom9.org What's on a DVD?, Retrieved on 2009-07-26
  9. ^ AfterDawn.com (2007-07-31) How to play VOB / IFO / BUP files, Retrieved on 2009-07-26
  10. ^ DVD Demystified (July 13, 2009) What are the copy protection issues?, Retrieved on 2009-07-28
  11. ^ DVD Demystified (July 13, 2009) DVD Frequently Asked Questions (and Answers) - Why can't I play movies copied to my hard drive?, Retrieved on 2009-07-28
  12. ^ a b What are the copy protection schemes used in DVD ? What is CSS ?, Retrieved on 2009-07-28
  13. ^ a b DVD Demystified (July 13, 2009) What are .IFO, .VOB, .AOB, and .VRO files? How can I play them?, Retrieved on 2009-07-28
  14. ^ Doom9's forum (2002-2005) DVD-RAM *.VRO File Conversion, Retrieved on 2009-07-28
  15. ^ DVD-VR Application format notes, Retrieved on 2009-07-28


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