Temporal synchronization models for multimedia data

Multimedia information systems are considerably more complex than traditional ones in that they deal with very heterogeneous data such as text, video, and audio-characterized by different characteristics and requirements. One of the central characteristics of multimedia data is that of being heavily time-dependent, in that they are usually related by temporal relationships that must be maintained during playout. We discuss problems related to modeling temporal synchronization specifications for multimedia data. We investigate the characteristics that a model must possess to properly express the timing relationships among multimedia data, and we provide a classification for the various models proposed in the literature. For each devised category, several examples are presented, whereas the most representative models of each category are illustrated in detail. Then, the presented models are compared with respect to the devised requirements, and future research issues are discussed