Scaleable audio service for collaborative virtual environments over Internet

We describe an audio-service for network applications, designed to support many simultaneous speakers and to operate across the Internet. Our service exploits a technique called distributed partial mixing to dynamically adapt to varying numbers of speakers and network congestion. A collection of networked audio mixers is arranged as a distributed graph. Each mixes subsets of its input audio streams into one or more mixed streams, which it forwards along with any unmixed streams. This reduces network traffic but at the cost of also reducing audio quality. An experiment demonstrates how our implementation dynamically manages the trade-off between congestion and audio quality when compared to the approaches of peer-to-peer forwarding and total mixing. We also demonstrate how our approach can be realised in a way that is fair to the TCP protocol and so operates as a "good Internet citizen".