intermedia synchronization management in dtv systems
Intermedia synchronization is related with spatial and temporal relationships among media objects that compound a DTV application. From the server side (usually a broadcaster's server or a Web Server) to receivers, end-to-end intermedia synchronization support must be provided. Based on application specifications, several abstract data structures should be created to guide all synchronization control processes. A special data structure, a labeled digraph called HTG (Hypermedia Temporal Graph) is proposed in this paper as the basis of all other data structures. From HTG, receivers derive a presentation plan to orchestrate media content presentations that make up a DTV application. From this plan other data structures are derived to estimate when media players should be instantiated and when data contents should be retrieved from a DSM-CC carousel or from a return channel. If the return channel provides QoS support, another data structure is derived from the presentation plan, in order to determine when resource reservation should take place. For content pushed by broadcasters, HTG is used in the server side as the basis for building the carousel plan, a data structure that guides the order and frequency that media objects should be broadcasted. The paper's proposals were partially put into practice in the current open source reference implementation of the standard middleware of the Brazilian Terrestrial Digital TV System. However, this reference implementation is used just as a proof of concept. The ideas presented can be extended to any multimedia document presentation player (user agent) and content distribution server.
intermedia synchronization temporal graph middleware digital tv ncl