A novel wide-band audio transmission scheme over the Internet with a smooth quality degradation

Abstract

Real-time delivery of multimedia information over the Internet is finding increasing interest. This paper considers wide-band audio transmission utilizing a priority scheme. The proposed scheme complies with both the new Internet Protocol Version 6 (IPv6) and the current Internet Protocol Version 4 (IPv4), providing that, in the latter case, routers are set to manage priority. A new queuing algorithm, namely Priority Weighted Fair Queuing (PWFQ), is defined and evaluated. A scalable audio encoder is adopted to perform audio transmissions over an emulated network. Background traffic is emulated, employing a traffic generator that adopts a self-similar model. Objective and subjective quality tests are performed, using a set of musical excerpts. Quality is evaluated as a function of Internet traffic. In the paper it is shown that, by adopting an encoding technique with scalable bit-rate, and a prioritized transmission algorithm, a smooth degradation of quality may be obtained during network congestion periods. This technique shows better performance than feedback-based algorithms, in which the delayed responses cause the core stage packets to be lost in low-to-high traffic transitions and the enhancement packets not to be transmitted in high-to-low traffic transitions.