SUPPORTING RANDOM-ACCESS ON REAL-TIME RETRIEVAL OF DIGITAL CONTINUOUSMEDIA

In addition to the large data size requirement and real-time constrain t in continuous media, future video applications such as video editing demand a random access capability at the video-frame level. This pape r introduces our study on effective buffering control for the real-tim e retrieval of jitter-free digital video medium. We adopt a video-fram e level approach to maintaining the flexibility on placement and analy sing the efficiency of the buffering schemes. An integrated solution w hich offers efficient buffering schemes and flexible storage placement to support random access is our goal. We present two buffering scheme s: the two-buffer scheme and the k-buffer compensation scheme. The two -buffer scheme requires that all the frames in a block are stored cons ecutively, while providing random access between blocks. However, this intuitive buffering scheme potentially requires a large block size an d buffer space. The k-buffer compensation scheme is proposed to resolv e this large buffer space requirement, by using more than two buffers and requiring a minimal number of blocks randomly placed in each cylin der. This scheme differs from the contiguous placement scheme because individual blocks can be stored anywhere in each cylinder. Compared to the two-buffer scheme, the k-buffer compensation scheme requires less buffer space, has higher disk utilization and finer granularity on di sk data transfer. The placement requirements are more flexible and imp lementable than the contiguous and storage pattern placement schemes. Experimental measurement results reveal the significant improvements o n the buffer-size reduction and placement flexibility by using the k-b uffer compensation scheme. Extensions of the k-buffer compensation sch eme to support multiple streams are also addressed.