In this paper, a novel multimedia transmission server system is designed using rule-based expert system technology. Working parameters and session management methods are separated from the decisionmaking procedure and stored in a knowledge base (XML format). The server fires different transmission strategies inside the knowledge base by runtime inference. Thus it can easily adjust transmission parameters under various environments and incorporate newly developed methods without significantly changing the main body of the server code. Results indicate that the expert system can efficiently deliver smooth streams and save server resources. The overhead brought along with the flexibility is tested to be acceptable.

This article describes an optimized filtering scheme (OFS) for layered video streaming system to improve the user-perceived quality. Based on content characteristics, this scheme filters the MPEG-4 video objects according to the derived optimized transmission path along the object structure so that the average decoding quality is maximized and quality variance is minimized. With proposed algorithms, OFS can also achieve close target bit rate match with low computational complexity. Compared with three traditional media filters, we demonstrate the effectiveness of OFS by extensive simulations.

Media proxy caching is an efficient method to provide instant access to multiple video objects in video streaming system. Research efforts in this area are not sufficient due to the possible huge number of heterogeneous requests to scalable encoded video objects. In this paper, we propose an optimized caching scheme for scalable video objects so that both transmission cost and access latency are minimized. A multi-objective optimization model is developed and the corresponding algorithms are designed. Our evaluation results show that compared with other caching methods, proposed scheme can achieve a significant reduction in transmission cost with even a small proxy cache size.

In this work, we investigated the discrete linear quadratic (DLQ) rate control method for the transmission of MPEG2 streams in IP networks. We derived a transmission scheduling system by solving the DLQ control problem under disturbances. Our study shows that DLQ is superior to conventional proxy scheduling schemes especially in client buffer usage. For some videos that can only achieve 70%/spl sim/80% of buffer usage using basic DLQ, we also propose improvements to attain higher buffer occupancy with no overflow. Transmission capacity and adjust method under heavy traffic are also discussed.

We describe a compensation method for real-time multimedia streaming to improve the user-perceived quality of video. Based on TCP friendly rate control (TFRC), this method takes advantage of the resources available at the proxy server and considers the content-aware principle as well. Using feedback from the client, the proxy server dynamically drops or compensates the enhancement layers of the MPEG-4 stream. We optimize performance by carefully choosing the compensation point to maximize the compensation effect, while at the same time meeting the constraints of the client buffer and realtime requirements. Compared to the traditional prefetch method, the proposed method can further improve the video quality, which is demonstrated through extensive simulations

A self-modifiable color Petri net model (SMCPN) that has multimedia synchronization capability is proposed in this paper. By introducing color tokens associated with basic commands, this model can handle user interaction flexibility. By combining numbers with the color tokens, SMCPN allows iteration to be modeled and hence is able to reduce the graph sizes of synchronous playback models while allowing greater details to be shown. SMCPN can also be used in the design and modeling of a multimedia tool with Memex functions like forward, backward, and trail history functions in a Web browser.