Results for a statistically optimal algorithm for multimedia receiver buffers

Abstract

For interactive multimedia and multimedia streams, receiver playout buffers are required to smooth network delay variations. Instead of using a constant playout speed, newer receiver buffer algorithms control the playout speed, which can give a lower end-to-end delay and fewer packets that are lost because of late arrivals. This paper presents a statistically optimal algorithm to control playout speed. The most significant difference to other published playout speed adjusting algorithms is the thorough mathematical approach that this work is based on. A stringent notation and stringent mathematical models of the media receiver system have been developed, which are generic and independent of the networks and protocols used. This has enabled us to deduce the statistically optimal controller for the playout speed, which is also independent of the networks and protocols used. Three deviations from perfect playout have been identified: (i) buffering delay (ii) a playout rate different from the sender rate and (iii) a change of playout rate. Our approach is statistically optimal by minimising the three deviations, based on their relative importance. The importance will vary for different user and application requirements, and is thus freely tunable by means of three weight factors. The optimal control algorithm is easy to implement and has demonstrated very good results when evaluated by perceptual evaluation of speech quality, an objective technique for measuring voice quality, and degradation mean opinion score, a subjective listening test, for both simulated and real network measurement traces.