The GBAR source model for VBR videoconferences

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