A buffer allocation mechanism for VBR video playback

Abstract

This paper presents a buffer allocation mechanism for VBR (variable bit rate) video playback. VoD (video on demand) is one of the multimedia applications which attract more attention. However, it remains a big challenge for real-time VBR-based VoD to achieve a satisfactory QoS, since the size of VBR video frames can be largely varied and the packets of each frame may encounter different delay variations. The proposed buffer allocation scheme allocates a suitable number of pre-buffers before video streams are pushed out from the server. We first build a mathematical model to estimate accurately the pre-buffer size based on the maximum and the minimum network delay. Then, we determine a better partition interval to minimize the percentages of average buffer size in empty. For the purpose of demonstration, we perform an experiment with a video server pushing video streams to clients through two routers. From the experiment, we have shown that the calculation results of the pre-buffer size before video playback and the dynamically allocated buffer sizes during video presentation are very close to those values from the actual measurements.