Maria Elena Bonfigli

Design and Experimental Evaluation of an Adaptive Playout Delay Control Mechanism for Packetized Audio for Use over the Internet

We describe the design and the experimental evaluation of a playout delay control mechanism we have developed in order to support unicast, voice-based audio communications over the Internet. The proposed mechanism was designed to dynamically adjust the talkspurt playout delays to the traffic conditions of the underlying network without assuming either the existence of an external mechanism for maintaining an accurate clock synchronization between the sender and the receiver during the audio communication, or a specific distribution of the audio packet transmission delays. Performance figures derived from several experiments are reported that illustrate the adequacy of the proposed mechanism in dynamically adjusting the audio packet playout delay to the network traffic conditions while maintaining a small percentage of packet loss.

Pervasive computing for interactive virtual heritage

The rapid evolution of pervasive computing technologies enables bringing virtual heritage applications to a new level of user participation. A platform for interactive virtual heritage applications integrates a high-end virtual reality system with wireless, connected portable and wearable computers, facilitating and enhancing user navigation, visualization control, and peer-to-peer information exchange.

A Design for a Simulation-based Multimedia Learning Environment

The development of high performance computing and communications is enabling the creation of new excit ing automated learning environments. In particular, the creation of richer distance learning environments has been obtained by merging together the World Wide Web with the educational features of multimedia and simulation technologies. However, most of todays Web-based courseware tools is often limited to the presentation of non-customized instructional ma terials. Those tools are in essence equivalent to computer assisted learning systems-they are static and unable to personalize the interaction with the user. Contrariwise, new-generation distance learning software tools should be able to exploit (i) adaptive mechanisms, (ii) Web technologies, and (iii) net worked multimedia and simulation in order to drive each different student through his/her personalized learning path. This paper presents the design and the multimedia/hypermedia architecture of a simulation- based distance learning tool which has been designed and developed to provide instructional support tai lored to the personal profile and needs of each different user.

A software audio terminal for interactive communications in Web-based educational environments over the Internet

This paper describes the software architecture of a multimedia educational tool which is suitable for delivering educational material over the World Wide Web under the different forms of HTML slides, digitized video-taped lessons, interactive and adaptive exercises and quizzes to solve, and real time synchronized audio. Such one Web-based educational tool embodies a software audio terminal that allows its users to conduct full-duplex, real time interactive audio conversations across the Internet. The authors discuss the main design issues of that audio terminal and report on several real-world experiments carried out over Internet connections that confirm the efficacy of the strategies they have adopted.