Abstract :
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
Keywords :
code standards; image sampling; image sequences; quantisation (signal); telecommunication networks; telecommunication standards; telecommunication traffic; variable rate codes; video codecs; video coding; MPEG-2 VBR video traffic; MPEG-2 standard; VBR coding; aggregate sequence; bandwidth allocation; codec quantization step reduction; constant quality; constant quantization step; efficiency; high-rate periods; movie; network bandwidth-allocation; network utilization; quality of service; sample; simulation results; traffic characterization; two quantization steps approach; video signal; Bandwidth; Channel allocation; Code standards; Codecs; Motion pictures; Quality of service; Quantization; Telecommunication traffic; Traffic control; Transform coding;
