Variable bit rate video in broadband ISDN

The introduction of Asynchronous Transfer Mode (ATM) based fast packet switched transport for Broadband Integrated Services Digital Network (BISDN) has made it possible to support a new range of high bandwidth variable bit rate services more efficiently. Of these new services, video based communications such as videotelephony, multimedia and interactive video and broadcast and entertainment video are expected to play a major role in the evolution of these networks. The goal of this work is to bring to light some properties of variable bit video which will be useful in designing networks and network protocols. The traffic characteristics of VBR MPEG encoded broadcast quality video sources are investigated. Detailed statistics for this source at different spatial resolutions are obtained utilizing a long video sequence. The effect of varying two key parameters on the traffic characteristics are presented. A new coding technique suitable for prioritized networks which partitions the bit stream into a high priority and low priority stream while maintaining compatibility with existing MPEG coders is introduced and its traffic characteristics are presented. The probability density function for the empirical density function is shown statistically to be similar to a gamma distribution. Statistical estimates of the transition probabilities for Markov chain models for the video sources are also presented. The effect of smoothing on traffic characteristics of video sources is also investigated. A procedure for obtaining ARIMA models for intraframe and mixed intra/interframe video sources is outlined. The effect on video sources of utilizing a leaky bucket as an admission and congestion control mechanism for ATM networks is also discussed. In particular it is shown that the leaky bucket parameters that are required for variable bit rate video services may not be feasible in practice. A predictive bandwidth allocation method for video sources in ATM networks is evaluated. Finally, the mapping of network performance to service performance is investigated for VBR MPEG video through the use of a modified cell loss measure. It is shown that this measure captures the true effect of losses on service performance better than the simple cell loss rate