| Multimedia communication has developed with data communication technology. Digital data communication has been improved in the 1990's,and it has been shown in IP network,wireless communication and multimedia application. Now video transmission over IP has attracted many researchers. This thesis has focused on the key technologies of video transmission system,including fine granular scalable video coding,congestion control and error control technology.In the first part,Internet structure and related protocols are analyzed,including TCP,RTP/RTCP schemes and network parameter measurement.In the second part,video coding principle and the issued standards,such as H.261,H.263,and MPEG-4 are investigated. The detailed fine granular scalable video coding technology and several improvements are presented.In the third part,a communication framework for fine granular scalable video stream is proposed. This framework has integrated video coding,decoding,congestion control and error control mechanism for video transmission.In the fourth part,some key technologies about fine granular scalable video coding,decoding and rate shaping are surveyed,including how to shape the stream to get a better PSNR,and how to allocate the rate of base and enhancement layer. A comparison study on the rate shaping analytic model of normal layered coding and FGS coding is presented.In the fifth part,this paper has fully analyzed the current congestion control mechanism,and proposed a novel TCP-friendly Loss-based Rate Control scheme (LRC) for unicast data transfer. This scheme is of better convergence and smoothness than AIMD algorithm. The simulation has verified the validation of it. As for congestion control for multicast transfer,this paper has presented a network node involved scheme,that is,to add FGS agent to network node to realize congestion control. This approach has made full use of the fine granularity character of FGS coding and reduces the complexity of the traditional congestion control scheme.In the sixth part,the paper has surveyed the error control schemes in video transmission. A new packetise algorithm is presented. A type of retransmission request is customized and the combination of FEC and retransmission is implemented. As for error concealment,a hybrid algorithm is developed,including searching of former frame,mode selection,combination of temporal and special error concealment and improvement of SAD. Experiment results in the network simulation by CLOUD show that the proposed scheme has provide a higher peak signal-to-noise ratio and much better visual quality than conventional approach.Finally,the whole paper is concluded and the tendency of the video transmission research in the future is pointed out.
|
PDF Full Text Request