Browsing by Author "Candan, K.S."
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Item Collaborative Multimedia Documents: Authoring and Presentation(1998-10-15) Candan, K.S.; Prabhakaran, B.; Subrahmanian, V.S.Multimedia documents are composed of different data types such as video, audio, text and images. Authoring a multimedia document is a creative exercise. Unlike traditional computer supported collaborative work where documents are composed of static objects, multimedia documents have temporal, spatial and quality of service (QoS) requirements that must be supported by any collaborative multimedia platform. In this paper, we show that most requirements (including temporal, spatial, and QoS requirements) for collaborative multimedia systems can be expressed in terms of a highly-structured class of linear constraints called difference constraints that have been well-studied in the operations research literature. As a consequence, well known algorithms for solving difference constraints may be used as a starting point for creating multimedia documents. Based on our difference-constraint based characterization, we develop efficient, incremental algorithms for creating and modifying multimedia documents so as to satisfy the required temporal, spatial and QoS constraints. We further develop methods to identify inconsistent requirements, and show how such inconsistencies may be removed through constraint relaxation techniques. (Also cross-referenced as UMIACS-TR-96-9)Item Collaborative Multimedia Systems: Synthesis of Media Objects(1998-10-15) Candan, K.S.; Rangan, V.; Subrahmanian, V.S.When a group I_1,... ,I_n of individuals wishes to collaboratively construct a complex multimedia document, the first requirement is that they be able to manipulate media-objects created by one another. For instance, if individual I_j wishes to access some media objects present at participant I_k's site, he must be able to; (1) retrieve this object from across the network, (2) ensure that the object is in a form that is compatible with the viewing/editing resources he has available at his node, and (3) ensure that the object has the desired quality (such as image size and resolution). Furthermore, he must be able to achieve these goals at the lowest possible cost. In this paper, we develop a theory of media objects, and present optimal algorithms for collaborative object sharing/synthesis of the sort envisaged above. We then extend the algorithms to incorporate quality constraints (such as image size) as well as distribution across multiple nodes. The theoretical model is validated by an experimental implementation that supports the theoretical results. (Also cross-referenced as UMIACS-TR-96-8)