Editing VOB (section)

==Copy protection==
Almost all commercially produced DVD-Video titles use some [[DVD Video#Restrictions|restriction]] or [[copy protection]] method, which also affects VOB files.<ref>DVD Demystified (July 13, 2009) [http://dvddemystified.com/dvdfaq.html#1.11 What are the copy protection issues?], Retrieved on 2009-07-28</ref>  Copy protection is usually used for [[copyright]]ed content.

Many 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 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 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.<ref name="dvdemystified">DVD Demystified (July 13, 2009) [http://dvddemystified.com/dvdfaq.html#4.5 DVD Frequently Asked Questions (and Answers) - Why can't I play movies copied to my hard drive?], Retrieved on 2009-07-28</ref><ref name="dvdreplica">[http://www.dvd-replica.com/DVD/dvdprimer-7.php What are the copy protection schemes used in DVD ? What is CSS ?], Retrieved on 2009-07-28</ref>  There are many CSS-decrypting programs, or [[ripping]] software, such as [[libdvdcss]], [[DeCSS]], [[DVD Decrypter]], [[AnyDVD]] or [[DVD Shrink]] which allow a protected DVD-Video disc to be played without access to the original key or copied to hard disk unscrambled. In some countries, their usage can be a violation of law (e.g. for non-personal use).<ref name="dvdreplica" />