Abstract
The use of formal probabilistic modelling together with advanced statistical inference in communications engineering, has the potential of providing a powerful workbench for deriving conclusions about the behaviour of systems and sources of data and therefore developing innovative and efficient control and management strategies of communication systems. Targeting the efficient dimensioning of systems and resources in order to make possible the provision of high-quality and larger-choice services to the end-users, this paper proposes the use of a Bayesian framework in video broadband communications. In the context of the combined transmission of several good-quality video sources, such as a digital television broadcast service, using VBR video encoding algorithms and based on prior beliefs and statistical models, an intelligent multiplexer is capable of predicting the probable amount of free space and fill it with extra services or increase the quality of the transmitted channels. © 2003 IEEE.

Abstract

Abstract
MPEG-21 enables content consumers to access and interoperate with a large variety of multimedia resources and their descriptions in a flexible manner. Considering the great heterogeneity that presently exists across the entire multimedia content chain and the growing importance of open standards to facilitate the interoperations across environments, applications and formats, an MPEG-21 Peer was developed to process and present complex multimedia content, represented as MPEG-21 Digital Items. The novelty of the work essentially relies on the adoption of a Web Services architecture, based on a single Digital Items processing core available for all types of terminal devices.

Abstract
An efficient algorithm for dynamically multiplexing MPEG2 encoded video sources is presented. Sources are grouped into classes regarding different combined levels of spatial detail and amount of movement. Simulations were performed using different associations of sources belonging to distinct classes, different bit rates and GOP structures. The implications associated to a real implementation are analysed and a modular architecture is proposed. Simulation results are presented and discussed, showing that sequences with higher spatial detail and motion are those which exhibit the higher quality improvements.

Abstract
In this paper we present an experimental approach for QoS-aware and bandwidth-efficient transmission of multimedia sources over ATM networks. VBR video sources are statistically multiplexed at the application level and the UPC parameters of a single connection for the aggregate traffic are dynamically renegotiated with the network during the session lifetime. A statistical multiplexer computes the required bandwidth for the aggregate traffic and dynamically assigns bandwidth according to the performances requested and network resources availability. A dynamic UPC manager using feedback information sent by the network, may initiate a renegotiation of traffic parameters upon receiving a request from the statistical multiplexer. Performing the connection admission control procedures for the aggregate traffic, allows significant reductions in the value of the total peak rate when compared to the sum of peak rates of individual connections. It also reduces the burstiness of the flow submitted to the network, thus increasing the lifetime of each set of UPC parameters. © Springer-Verlag Berlin Heidelberg 2000.

Abstract
Very few of the current solutions for content recommendation take into consideration the context of usage when analyzing the preferences of the user and issuing recommendations. Nonetheless, context can be extremely useful to help identify appropriate content for the specific situation or activity the user is in, while consuming the content. In this paper, we present a solution to allow content-based recommendation systems to take full potential of contextual data, by defining a standards-based representation model which accounts for possible relationships among low-level contexts. The MPEG-7 and MPEG-21 standards are used for content description and low-level context representation. OWL/RDF ontologies are used to capture contextual concepts and, together with SWRL to establish relationships and perform reasoning to derive high-level concepts the way humans do. This knowledge is then used to drive the recommendation and content adaptation processes. As a side achievement, an extension to the MPEG-21 specification was developed to accommodate the description of user activities, which we believe have a great impact on the type of content to be recommended.