THE GBAR SOURCE MODEL FOR VBR VIDEOCONFERENCES

A previous study examined three sequences giving the number of cells p er frame of a VBR encoding of videoconferences (talking heads); these sequences were produced by hardware encoders using different coding al gorithms, Each sequence had a gamma marginal distribution, and the aut ocorrelation function was geometric up-to lags of at least 3 s, which includes all autocorrelation values larger than 0.1. We present an eas y to simulate autoregressive process that has these properties. The mo del is tested by comparing the cell-loss rate produced when the data t race was used as the sole source in a simulation of an ATM switch to t he cell-loss rates produced when traces generated by the model were us ed as the source.