The QTPlgMovieVideoPlayVisualContext is an abstract class, derived from the class, that defines general behaviour for concrete subclasses to playback movies containing video using the new visual context abstraction implemented in QuickTime 7.0 and later.
The QTPlgMovieVideoPlayVisualContext classes use automatically CoreVideo display links to provide a separate high–priority thread to notify your application when a given display will need each frame. How often a frame is requested is based on the refresh rate of the display device currently associated with the display link (in case of QTPlgMovieVideoPlayVisualContext classes is always the main display).
Furthermore, QTPlgMovieVideoPlayVisualContext classes allows you to dinamically adjust and , in addition to and , for the movie being played.
The QTPlgMovieVideoPlayVisualContext subclasses require QuickTime 7.0 or later and MacOS X. This not being the case, a QTPlgMovieVideoPlayVisualContext object behaves exactly like a object.
→ → →
The QTPlgMovieVideoPlayVisualContext is an abstract class so you cannot instantiate objects directly from this class; instead, you will use objects created from its concrete subclasses such a and classes.
Anyway, once a subclass instance is returned, it is good practice to check the class property to be sure that the new object can be used. See the QTPlgMovieVideoPlay’s validity conditions for more details.