Specifying and Authoring Multimedia Scenarios

methodology and a set of checking tools let authors specify the spatial and temporal features of an application and verify the application prior to its execution. The checking tools include an animation tool, spatial and temporal layouts, and the execution table of the application. A multimedia application involves a variety of individual media objects, called actors, presented according to the application's scenario. The term scenario covers two areas: ❚ the spatial and temporal ordering of actors within the application and the relationships among them, and ❚ the way that users will interact with the application and how the scenario will treat application or system events. Actors participating in a multimedia application are usually transformed either spatially and/or temporally to meet the author's requirements. For instance, we may want to present part of a video clip faster or slower in a bigger or smaller window. The authoring procedure for complex multi-media applications involving a large number of actors proves a very complicated task. Authors must keep in mind the large set of possible events that may be encountered in the application context , the number of actors and relationships, and the potential combinations of these factors. The potential high complexity of multimedia applications demands substantial effort in designing and developing them. In real-life applications, usually only programmers can develop multime-dia application scenarios, since current authoring tools provide rather low-level specification languages. Moreover, these languages don't adequately describe the scenario aspects. Therefore, the lack of an integrated mechanism for a high-level, complete, multimedia application scenario specification proves problematic. Moreover, in current multimedia application development tools, authors mix the script with the application content (actors). This prevents the explicit reusability of scenarios in other multimedia applications with different content but similar func-tionality. Checking multimedia application scenarios for integrity during development remains another important issue. The term checking in this context implies the various procedures that let authors review the result of their work prior to producing and executing the application. This enables revisiting the application and adjusting the spatiotemporal specification in order to align to the document style the authors had in mind, or fixing specification errors that result in spatial and/or temporal exceptions. Figure 1 shows the multimedia application development procedures in terms of modules. You can see the two main phases, namely the specification and the checking phase. In the first, authors specify the transformation of the original multimedia objects in …