Cell Level Modelling of H.261 Coded Video Sequences at Different Bit Rates

A video source, with a low to medium activity, coded with an H.261 type video codec can be modelled at the frame level as an M state Markov chain. For cell level modelling, the generated cells within the frame are distributed using a modulated Poisson process with interarrivals of Gamma function. Sequences with scene cuts use an additional state in the Markov chain to represent the scene cut bit rate. The multiplexed model of N homogeneous sources is represented by a linear Markov model of N × M states. The transition probabilities in the multiplexed model are approximated by a truncated discrete normal distribution bounded within ±N states. The proposed single and multiplexed models exhibit similar cell loss performance with the real coded data at both cell and burst scale levels. The multiplexed model is then generalised to represent the aggregate traffic of several homogeneous sources at different bit rates.