Study of VBR MPEG-coded video traffic and associated multiplexing performance

This paper presents a study of the statistical characteristics and multiplexing of variable-bit-rate (VBR) MPEG-coded video streams. Our results are based on 23 minutes of video obtained from the entertainment movie 'The Wizard of Oz'. The experimental setup which was used to capture, digitize and compress the video stream is described. A particular significance of our data is that it contains the three types of MPEG frames, namely Intra-coded (I), Prediction (P) and Bidirectional (B) frames. Although the study is conducted at the frame level (as opposed to the slice level), it is observed that the inter-frame correlation structure for the frame size sequence involves complicated forms of pseudo-periodicity that are mainly determined by the compression pattern of the frames. We study the distribution of the frame size (i.e. the number of cells per frame). For each frame type, it is shown that a lognormal distribution is an appropriate fit for the frame size histogram. Simulations are used to study the performance of an ATM multiplexer for MPEG streams. Results from these simulations indicate that a significant gain in cell loss performance is obtained when MPEG video streams are statistically multiplexed.