Figurative privacy control of SIP-based narrowcasting

In traditional conferencing systems, participants have little or no privacy, as their voices are by default shared with all others in a session. Such systems cannot offer participants the options of muting and deafening other members. The concept of narrowcasting can be applied to make these kinds of filters available in multimedia conferencing systems. Our system treats media sinks (in the simplest case, listeners) as full citizens, peers of the media sources (conversants ' voices), and we defined therefore duals of mute & select: deafen & attend, which respectively block a sink or focus on it to the exclusion of others. In this article, we describe our prototyped system, which uses existing standard Session. Initiation Protocol (SIP) methods to control fine-grained narrowcasting sessions. The. design considers the policy configured by the participants and provides a policy evaluation algorithm for media mixing and delivery. We have integrated a "virtual reality"-style interface with this SIP backend to display and control articulated narrowcasting with figurative, avatars.