Enforcing Parental Management Levels
Any title or portion of a title on a DVD-Video disc can be assigned a generic parental management level (PML) from 1 through 8. When the DVD Navigator is reading content that has a PML, it is said to be in a parental block. A parental block may consist of part of a chapter, multiple chapters, or multiple titles. A DVD application intended for an international market should not hard code a particular rating system into its parental management logic.
The DVD Navigator itself does not enforce the PMLs; it merely informs your application when it encounters PML information on the disc. By default, it ignores this information on the disc and plays the highest level content. To enforce the PMLs, your application must implement some form of password control logic that associates users with levels, instruct the DVD Navigator to send it PML event notifications (by calling the IDvdControl2::SetOption method on startup, with the parameters DVD_NotifyParentalLevelChange and TRUE), and respond to those events to allow or disallow access as appropriate.
A DVD title can have one overall PML, but disc authors can give certain sections of that title higher or more restrictive PMLs. These are called temporary PML commands; these commands always contain two branching instructions: one to follow if the temporary PML command is accepted by the player application, and the other to follow if the command is rejected. The sequence of events is as follows. The DVD Navigator is reading video content (DVD Title Domain) when it encounters a temporary PML command on the disc. It checks its internal flag to see whether the application has requested to be notified of this event. If the flag is not set, the DVD continues playing, following the "parental level change rejected" branch specified on the disc. If the flag is set, the DVD sends an EC_DVD_PARENTAL_LEVEL_CHANGE event to the application and waits in a paused state until it gets a response. When your application receives the event, it uses its own logic to determine whether to accept the command. It then calls IDvdControl2::AcceptParentalLevelChange with an argument of TRUE or FALSE. If TRUE, the DVD Navigator resumes playing, following the "parental level change accepted" branch specified on the disc. Otherwise it resumes playing and follow the "parental level change rejected" branch.