Abstract

Distributed Partial Mixing is an approach to creating a distributed audio service that supports optimisation of bandwidth utilization across multiple related audio streams (e.g. from concurrently active audio sources) while maintaining fairness to TCP traffic in best effort networks. Rate adaptation of streamed audio is difficult because of its rate sensitivity, the relatively limited range of encoding bandwidths available and the potential impact on the end user of rate-adaptation artefacts (such as changes of encoding). This paper describes and demonstrates how our design combines TCP-fairness with the stability that is desirable for streaming audio and other rate sensitive media. In particular, our design combines: a distributed multi-stream management/mixing architecture, loss event and round-trip time monitoring, rate limiting based on a TCP rate equation, tuned increase and decrease strategies and a loss-driven network probing mode. Experimental validation is performed over a wide range of network conditions including against various congesting levels, TCP and independent DPM traffic.

Citations