[1] Different types of multimedia that can be transmitted with MPEG-4 appear in the scene above, a man and his infant son on-line with his offstage wife. The tree chart below, called a scene graph, represents the media as independent or compound objects. One compound object comprises the father and child (an arbitrarily shaped video) and the audio track of his voice. Other objects are the floor and walls--"sprites," here used for easily changed backgrounds; the Web site of the furniture store--an application mapped as a screen texture; and the computer-generated (synthetic) furniture the father has chosen from the Web site for his wife to look at and interactively move around. Simultaneously playing on a synthetic HDTV set is a movie from the family's home digital versatile disk (DVD).
(c) Copyright 1999, The Institute of Electrical and Electronics Engineers, Inc.