Traditional media, such as text, image, audio and video, have long been the main media resources and granted full support of standard desktop tools and applications. Interactive rich multimedia documents, adding resources such as video or synthetic animations and relying on complex synchronization among objects, are now making their entrance into the world as new multimedia formats emerge. In this context, the Synchronized Multimedia Integration Language (SMIL) is receiving more and more attention from content authors due to its fine property of multimedia synchronization and authoring interactivity for the content production. At the same time, MPEG-4 is designed to address the requirement of new generation of highly interactive multimedia applications, while simultaneously maintaining the support of traditional applications. MPEG-4 provides facilities (XMT and BIFS) to integrate and synchronize, spatially and temporally, many different media objects together. However, these facilitie...