Creating non-decomposable stream bundles in multimedia web services using uSMIL

Technical advances in networks, operating systems and web based services are enabling new web-based services such as audiovisual surveillance, monitoring and recording of unfolding real world scenes. Leaving room to alter the chronology of such real-world recordings would facilitate the ability to fabricate audiovisual evidence, thereby seriously eroding emerging public trust on these up and coming services. One way of avoiding this problem is to be able to specify which chronology building composition operators - otherwise known as multimedia synchronization constructs - such as before, after, simultaneously etc., have more rigid failure semantics. Existing W3C standard for multimedia services, the synchronized multimedia integration language (SMIL) does not provide them. In order to address this deficiency, we propose uSMIL - an extension of SMIL that allows the creation of non-decomposable stream bundles with an all or nothing playout semantics. Here we present a report on our work in progress that defines a formal operational semantics for uSMIL and show some of its algebraic properties.