In this scenario, the MPEG-4 receiver may be a home set-top box, say, part of a high-end home theater, and may be connected to a high-bandwidth broadcast network at its input end. The receiver could also be a conventional multimedia terminal connected to the broadcast network. With the advent of digital broadcasts, the broadcast networks are not limited to the conventional satellite or cable networks that were the only available options until recently. The Internet can now be considered to be an instance of a broadcast network too. The key concept of MPEG-4 is "create once, access everywhere," and the tools that support it allow content creators and service providers to make their content available across the entire range of available delivery systems.
Figure 18 shows simple features such as interactive enhancement of the broadcast streams. They can easily be extended to support many applications, such as interactive home shopping, enriched documentary programming, advanced electronic services and program guides, interactive advertisements, interactive entertainment like sports programs or quiz shows, viewing of Web-like content, and demographically focused programming.
FIGURE 18 Interactive broadcast. (Courtesy of Gianluca De Petris et al., IBC demonstration from the Advanced Interactive Content Initiative. Used by permission.)