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Traffic characterization and bandwidth allocation for MPEG-2 VBR video traffic

Starting from a long sample (about one hour) of the movie "The Sheltering in the Sky", coded according to the MPEG-2 standard with 2 different quantization steps, we study the characteristic of this traffic to identify efficient network bandwidth-allocation policies. We evaluate the efficiency that can be obtained by maintaining a constant quality, i.e., VBR coding with a constant quantization step. Results obtained indicate that traffic with constant quality can be transmitted with a suitable quality of service only if the network utilization is very low, i.e., 25-30%. As the low network utilization is caused by rare high-rate periods lasting a few seconds, we propose to reduce the codec quantization step during these periods. Simulation results show that the two quantization steps approach significantly increases the utilization while maintaining the quality of the video signal at the highest value for most of the time, e.g., a 50% network utilization with the highest quality for 99.7% of the time.