QuickTime 3 introduced a way to tailor the movie data displayed to the user according to a much wider array of environmental characteristics, including the , the that is installed on the user’s machine, and the . This magic is accomplished with alternate movies. An alternate movie is any one of a set of movies that contain media data appropriate for a specific characteristic or set of characteristics. For instance, one alternate movie might contain highly–compressed video and monophonic sound, while a second alternate movie contains higher–quality video and stereo sound. Because it is smaller in size, the first alternate movie would be appropriate for users with relatively slow Internet connections; the second movie would be appropriate for users with faster Internet connections. Similarly, one alternate movie might be appropriate for playback under QuickTime 6 and another might be appropriate for playback under all earlier versions of QuickTime.
Alternate movies are associated with one another using a movie file that contains data references to all of the alternate movies as well as information about the criteria by which QuickTime should select one of those alternate movies when that movie file is opened. This other movie file is called an alternate reference movie file (or, more briefly, a reference movie), since it refers to a set of alternate movies. When the principal selection criterion is the user’s Internet connection speed, this movie is sometimes also called an alternate data rate movie.
The QTPlgMovieAlternate class allows you to create reference movies within Realbasic.
The QTPlgMovieAlternate class constructors are called when you create a new instance of the class, while the ˜QTPlgMovieAlternate class destructor, is called automatically when the class is no more in use. Also, you can invoke the class destructor by setting the instance of the class to nil.
The class provides you with the following initializer methods: