DESIGN AND IMPLEMENTATION OF A MULTICAST AUDIO CONFERENCING TOOL FOR A COLLABORATIVE COMPUTING FRAMEWORK

CCFAudio is an Internet based audio conferencing tool with additional features tailored for use in a collaborative session. Considerable eff ort was spent to achieve audio quality comparable to telephone (confer ence) calls. CCFAudio supports several audio encoding schemes, and smo oth playback even under adverse network conditions. It supports multip le simultaneous speakers, mixing their voices in real-time. CCFAudio s ends audio packets to other participants via a non-Mbone multicast. It takes full advantage of multithreading in providing smooth playback a s well as simplified code. CCFAudio consists of three subsystems. The ''send-audio'' subsystem packetizes voice samples from a source transm its them to other tools. The ''receive-audio'' subsystem receives pack etized voice samples from multiple sources, mixes the samples and play s the result. The graphic user interface (GUI) subsystem provides a po int and click interface for controlling audio parameters as well as gr aphical feedback showing who is in the conference and who is speaking at any time. After initial setup of these parameters, operation of CCF Audio is completely hands-free. (C) 1998 Published by Elsevier Science Inc. All rights reserved.