Influence of Available Bandwidth on the Statistical Characterization of Compressed Video

The design and analysis of robust networking protocols that offer useful performance guarantees requires accurate traffic source models. In this paper we study the problem of characterizing and modeling the arrival process of compressed video. We extend earlier works in this area by including a factor that has previously been ignored, the effect of video capture rate on traffic characterization. Dynamic changes in available bandwidth due to the addition and/or removal of connections can trigger re-negotiation of bandwidth between the applications and the network. Such re-negotiation may result in applications changing the capture rate of video sequences, thus effecting the traffic generation process. We show that for several popular video coding schemes, the bit rate distribution at the output of the encoder changes with the capture and compression rate. Using a combination of distributions, and exploiting knowledge of the underlying compression algorithms we characterize variable bit rate (VBR) video by application type, compression algorithm, and frame rate. We conclude that no single distribution can describe all video traffic, and as an alternate suggest a three dimensional matrix in which each dimension represents a different video classification aspect. Each entry in this matrix is a distribution type that best fits the given combination of the aspects. We use this result to show how the problem of network capacity planning may be tackled.