VBR video data scheduling using window-based prefetching

Abstract

The MPEG data used in a video server has variable bit rate (VBR) characteristics because each frame is different in size, and the difference of movements between frames is also variable. So, a video server must consider this VBR characteristic in resource management. So far, for VBR data, many scheduling schemes have been proposed. When VBR video is displayed, if disk bandwidth is allocated assuming the worst case, the utilization of disk bandwidth becomes very low. In order to raise the utilization of disk bandwidth, a prefetching scheme is used, but this needs extra buffers. We propose a WVS (Window-based VBR data scheduling scheme) for VBR data. WVS prefetches data with a limited maximum bandwidth for each window unit. Moreover, WVS, which considers the state of system resources, can obtain a tradeoff between disk bandwidth and buffer allocation. The proposed scheme constructs in advance CTL (Constant Time Length) meta data about a video and dynamically allocates resources for each window unit. In simulations, we compared the proposed scheme with previous schemes in terms of the size of resource allocation and the number of concurrent users.