Adaptable software for communications in video conferencing

Video conferencing systems (VCS) have become practical in commercial and research institutions because the advances of technologies in networking and multimedia applications. A video conferencing session involves multiple parties, possibly geographically interspersed, which exchange real-time video data. How anomalies such as site failure and network partitioning affect the effectiveness and utilization of the communication capabilities. Video conferencing systems lack the ability of dynamically adapting themselves to the variations in the system resources such as network bandwidths, CPU utilization, memory and disk storage. In VCS, changes in parameters such as frame sizes, codec schemes, color depths, and frame resolutions can be agreed upon by users interactively based on their requirements for Quality of Service. They cannot be made automatically based on the distributed system measurements of currently available resources. We need to limit the users' burden in keeping the system running in the most suitable mode to current environment and make it possible to provide the best possible service based on the status of the system. Incorporating adaptability into a video conferencing systems minimizes the effects of the variations in system environments on the quality of video conference sessions. In this paper we present the following. First we briefly discuss the concept of adaptability and the basic idea for achieving adaptability in a video conferencing system. Next to identify and describe some of the common anomalies encountered in a distributed system. We further characterize the Quality of Service parameters in terms of timeliness, accuracy, and precision. These parameters are also identified in different layers of the software. We give an overview of the NV video conferencing system which serves as the testbed of our experiments. Then we describe the extension and modification to NV and discuss some reconfiguration issues. Finally, a summary of experimental data analyses, observations, and discussions are presented. Specifically we show how VCS parameters affect the communication and computing. Next we present some guidelines for maintaining timeliness and accuracy when bandwidth decreases. We are conducting a series of experiments that will lead in the development of policies for adaptability at the application, system, and network layer to meet the quality of service requirements. Next we study the impact of network constraints in determining the quality of service that can be guaranteed to the user. Based on these experiments, we plan to identify guidelines and expertise that will allow the applications and network to meet the quality of service requirements at all layers.