Efficient support for interactive scanning operations in MPEG-based video-on-demand systems

Abstract

In this paper, we present an efficient approach for supporting fast-scanning (FS) operations in MPEG-based video-on-demand (VOD) systems. This approach is based on storing multiple, differently encoded versions of the same movie at the server. A normal version is used for normal playback, while several scan versions are used for FS. Each scan version supports forward and backward FS at a given speedup. The server responds to an FS request by switching from the normal version to an appropriate scan version. Scanning versions are produced by encoding a sample of the raw frames using the same GOP pattern of the normal version. When a scanning version is decoded and played back at the normal frame rate, it gives a perceptual motion speedup. By being able to control the traffic envelopes of the scan versions, our approach can be integrated into a previously proposed framework for distributing archived, MPEG-coded video streams. FS operations are supported using no or little extra network bandwidth beyond what is already allocated for normal playback. Mechanisms for controlling the traffic envelopes of the scan versions are presented. The actions taken by the server and the client's decoder in response to various types of interactive requests are described in detail. The latency incurred in implementing various interactive requests is shown to be within an acceptable range. Striping and disk-scheduling strategies for storing various versions at the server are presented. Issues related to the implementation of our approach are discussed.

Adaptive hybrid error correction model for video streaming over wireless networks

“…The UEP identifies the unequal importance of video data in the hierarchical video coding structure and gives the video data different amounts of protection according to the importance. In MPEG, the UEP exploits the difference in importance among frames (i.e., the I, P, and B frames) in a GOP and allocates more protection bits to the I frame than to the P and B frames [23,24]. Different UEP mechanisms have been proposed for various types of scalable video coding.…”

Qos for wireless interactive multimedia streaming

“…These approaches introduce visual discontinuities during the interactive mode, due to the missing video information. Alternatively interactive functions can also be supported using separate copies of the movie that are encoded at lower quality of the normal playback copy [9], [10]. In these cases, there is no significant degradation in the visual quality.…”