User operation prohibition
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The user operation prohibition (abbreviated UOP) is a form of use restriction used on video DVD discs. Most DVD players prohibit the viewer from performing a large majority of actions during sections of a DVD that are protected or restricted by this feature, and will display the no symbol or a message to that effect if any of these actions are attempted. It is used mainly for copyright notices or warnings, such as an FBI warning in the United States, and "protected" (i.e., "unskippable") commercials.
[edit] Countermeasures
Some DVD players ignore the UOP flag, allowing the user full control over DVD playback. Virtually all players that are not ad-hoc DVD player hardware (for example, a player program running on a general purpose computer) ignore the flag. There are also modchips available for some standard DVD players for the same purpose. The UOP flag can be removed in DVD ripper software such as: DVD Decrypter, DVD Shrink, AnyDVD, AVS Video Converter, MacTheRipper, HandBrake and K9Copy.
[edit] Counter-countermeasures
Nevertheless, removing UOP does not always provide navigation function in the restricted parts of the DVD. This is because those parts are sometimes lacking the navigation commands which allow skipping to the menu or other parts of the DVD. This has become more common in recent titles, in order to circumvent the UOP disabling that many applications or DVD players offer.
[edit] External links
- User Prohibited Operations flag documentation, Unofficial DVD Specifications
- U.S. Patent 6,553,180
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