User operation prohibition

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The user operation prohibition (abbreviated UOP) is a form of digital rights management 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 was intended for copyright notices and legal notices, such as an FBI warning in the United States. Some publishers run "protected" (i.e., "unskippable") commercials on their DVDs, which is widely seen by consumers as an abuse of the feature.

[edit] Countermeasures

Some DVD players ignore the UOP flag, allowing the user full control over DVD playback. Virtually all players that are not "special-purpose" 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, although modifying a device may be illegal in some countries. The UOP flag can be removed in DVD ripper software such as: DVD Decrypter, DVD Shrink, AnyDVD, MacTheRipper 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.