A GoP-based dynamic scheduling scheme for fast scan functions with a certain speedup playback rate

摘要

Since the advent of high-speed computer networks and compression techniques, recently there have been many studies on multimedia applications such as Video-On-Demand (VOD) for a stored video. VOD is expected to provide a user with interactive operations such as VCR functions. In particular, fast scan functions with a picture like 'Fast Forward' or 'Fast Backward' for a certain speedup playback are required. Since they require large amount of system resources, a scheme to reduce bandwidth requirements for the network or disk is needed. In a stored video, unlike in a real-time video, since the statistical characteristics of a full video stream is known before its transmission, prefetching sufficient data from a server is possible before the playback at a client. Thus, a server transmits a video stream based on the bandwidth smoothing while requiring the minimum network bandwidth. It is practical to support fast scan functions based on Group-of-Pictures (GoP) which is a random access unit for VCR functions in the MPEG standard. Accordingly, in this paper we present a dynamic scheduling scheme to support fast scan functions with m-times normal playback rate for a stored video stream. The proposed scheme writes a transmission schedule for a certain playback rate at the frame position where a user requests fast scan functions. That is, the scheme constructs the data set to be smoothed by skipping GoPs according to the speedup factor and then writes the transmission schedule by applying a bandwidth smoothing. Finally, the scheme restarts the transmission of video data to a client according to the new schedule. The proposed scheme results in speeding up the playback rate by utilizing 'GoP skipping' and reduces the computational complexity by applying a bandwidth smoothing based on GoP.