Obtain a MPEG-2 trace from the Internet. Find out the actual size of I-, P-, and B-frames from the trace. You then need to report the maximum, average and minimum sizes of all three types of frames.
The Answer
Designing an effective and high performance network requires an accurate characterization and modeling of network traffic. The modeling of video frame sizes is normally applied in simulation studies and mathematical analysis and generating streams for testing and compliance purposes. Besides, video traffic assumed as a major source of multimedia traffic in future heterogeneous network. Therefore, the statistical distribution of video data can be used as the inputs for performance modeling of networks.
the best fit for the distribution of frame sizes was lognormal distribution among gamma, Weibull, and lognormal distributions. They used the fitting distribution for three types of frame sizes such as I frames, B frames, and P framesFitzek and Reisslein [14] have provided a public available library of frame size sequences including MPEG-4, H. 263, and H.263+ encoded video with a detail of statistical analysis of generated traces.
The trace has approximately 5300 I frames with a maximum size of 130 Kbytes It can be observed that the frame sequence is coarsely composed by intervals in which I frames are relatively close in size. These I frames are thematically connected forming a scene.
Similar parsing of the trace file, in order to identify and extract the volume of the B frames is performed. approximately 80,000 B frames are included in the video. This number is in accordance with the number of I frames.
Figure 4 also depicts the size of the B frames. Specifically, the maximum size of B frames reaches the 50 Kbytes (with some exception at s almost 70 KBytes) which is approximately one third of that of I frames. mean value = −0.2713 and sigma = 4.2472.
In fact, B Frames have information only for the changes between the current frame and both the previous and the next frame; so their size should be smaller than the size of the corresponding I frames.After fitting the actual data upon the lognormal, the parameters that occur are: mean value = 0.8795 and Sigma = 1.0309.