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Research On The Techniques Of Multiple Description Coding And Video Transmission In The Internet

Posted on:2004-08-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:C H CaiFull Text:PDF
GTID:1118360092980610Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
This dissertation deals with several key techniques for video transmission in the Internet, including wavelet motion compensation video coding, multiple description coding, and transmission bit-rate control, etc. First, the paper presents a scheme of the X-tree image coding. An X-tree is a hierarchical quadtree whose all descendants are insignificant, and it is used to denote 2-D clustered insignificant wavelet coefficients of an image. The coding efficiency of two proposed X-tree based coding schemes, the progressive X-tree approach and the simplified X-tree approach, are much better than that of the EZW. Based on these approaches, an all-phase wavelet motion compensation framework with fast arithmetic X-tree video codec is proposed to realize high efficiency and low distortion video coding. The all-phase wavelet motion compensation successfully eliminates the shift-variant property of the wavelet transform, and outperforms the spatial motion compensation and direct wavelet motion compensation.Second, a multiple description coding approach based on significant coefficient decomposition is presented, where each significant wavelet coefficient is decomposed into two coefficients. One is made from the bits in the odd positions, whereas, the other is made from the bits in the even positions. These two types of coefficients are then grouped into two sub-signals,which form two descriptions of coded data and transmitted over different channels. If one description is lost, it can be recovered by the primary and redundant coding from another description. Redundant coding rate is reduced by using the structure consistency between two sub-signals and the performance is improved. Experimental results have shown that the performances of the proposed scheme are better than those of the polyphase transform and selective quantization one.Third, a linear model between the percentage of significant coefficients in total pixels and output bit-rate is developed by analyzing R-D characteristics of wavelet transformed images. Given the percentage, a quantization stepsize can be found easily from a histogram, so the proposed algorithm can control output bitrate easily, quickly, and accurately. It can efficiently make use of channels and reduce distortion.Finally, a quaternion based color edge detector is proposed and a self-adaptive color reconstruction algorithm for Bayer pattern is developed...
Keywords/Search Tags:Wavelet transform, Video transmission, Image coding, Motion compensation, Multiple description coding, bit-rate control
PDF Full Text Request
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