Piecewise fixed-rate retrieval scheme for variable bit rate video

Abstract

We consider the retrieval of variable bit rate (VBR) video from the distributed video server. Video servers often employ the constant rate retrieval scheme, in which a fixed amount of disk bandwidth is reserved throughout the retrieval to guarantee the continuous playback requirement. In constant rate retrieval, the allocated disk bandwidth is not always fully utilized in order to avoid excessive prefetch buffer requirement. This results in poor disk bandwidth utilization. We present a novel retrieval algorithm for stored variable bit rate video called piecewise fixed rate retrieval scheme. This scheme divides the total retrieval duration into several intervals during which a constant amount of disk bandwidth is reserved in order to maximize the disk bandwidth utilization. We examine the effectiveness of the retrieval scheme through extensive simulation studies. Compared to existing retrieval schemes, piecewise fixed rate retrieval achieves the greatest reduction in retrieval rate variability of disk bandwidth allocated, and results in high disk bandwidth utilization.