Modelling prioritized MPEG video using TES and a frame spreading strategy for transmission in ATM networks

This paper presents an efficient transmission mechanism, using frame spreading, for variable bitrate (VBR) MPEG compressed video, through an ATM multiplexer, such as a cable head-end. A priority scheme is implemented in a software MPEG encoder which produces a proportionate traffic in both (i.e., high and low) priority partitions for all three frame types (intraframe, predicted and interpolated) used in MPEG. An ATM multiplexer with a pushout buffer scheme is implemented for the study, in order to provide priority scheduling at the multiplexer for the two priority partitions. The multiplexer is fed with VBR MPEG traffic and performance statistics such as the cell loss ratios are studied for various frame spreading scenarios. Two statistical models are developed using TES (transform expand sample) for VBR MPEG video having two levels of priority. The first model is matched with the empirical histogram and autocorrelation function of each frame type (I, P and B). The second model is created with the assumption of a gamma distribution for the number of bits in each frame type. Experiments are conducted using both models and the results are compared.