Chinese Journal of Computers   Full Text
Title	A Robust and Flexible Unbalanced Multiple Description Video Coding and Transmission Scheme
Authors	LI Bin HUANG Feng SUN Li-Feng YANG Shi-Qiang
Address	(Department of Computer Science and Technology, Tsinghua University, Beijing 100084)
Year	2008
Issue	No.7(1155—1164)
Abstract &   Background	Abstract This paper propose a flexible and robust unbalanced multiple description coding and transmission scheme, which is capable of quickly recovering from packet losses and ensuring continuous playback, and further adaptive to both multiple path and single path transmission. Furthermore, this paper discusses the problem of rate allocation between different descriptions when only single path transmission is available and proposes an approximate while efficient rate allocation scheme with the help of two-state Markov link model and a representative rate-distortion model. The experimental results demonstrate the effectiveness of the proposed scheme. Keywords multiple description coding; unbalanced multiple description coding; rate allocation; video coding; transmission scheme Background Video transmission over networks is hampered by packet losses. Even a single packet loss may cause error propagation until an intra-coded frame is received. Indeed, packet losses greatly degrade the video quality. To address the issue, many methods are proposed. A general method to limit error propagation is to insert intra coding frames. However the high bitrate makes it particularly difficult to apply in many applications. Forward Error Correction (FEC) codes can also be deployed to increase the robustness of the coded bit-stream and thus reduce the length of error propagation. Nevertheless, the obvious obstacle thrown in the way of FEC codes is that its correction capability is fixed when given a predetermined redundancy. A pattern of excessive packet losses essentially results in incapability to correct errors, thus causing severe quality degradation. Another well-known error-protection method, i.e. Automatic Repeat reQuest (ARQ) technique is not suitable for live video applications because of the stringent constraints on the packet delivery deadlines. Fortunately, an alternative approach to tackle the problem of error propagation is applying Multiple Description Coding (MDC) techniques. Attractive feature of low delay property makes MDC most promising especially for live video applications. As long as the descriptions do not encounter packet loss concurrently, an acceptable quality could be obtained. This paper proposes a novel flexible and robust unbalanced multiple description coding and transmission scheme, which is capable of quickly recovering from packet losses and ensuring continuous playback, and further adaptive to both multiple path and single path transmission. Furthermore, it discusses the problem of rate allocation between different descriptions when only single path transmission is available and propose an approximate while efficient rate allocation scheme with the help of two-state Markov link model and a representative rate-distortion model. The experimental results demonstrate the effectiveness of our proposed scheme. This research is supported by the National Natural Science Foundation of China under grant No. 60503063. It is also partly supported by the National Basic Research Program of China (973) under grant No. 2006CB303103.