| Heterogenous. network issues a challenge to traditional video coding technique. Since traditional video.coding bit stream does not have flexible bit rate adjustment function or only has limited bit rate adjustment function, which is difficult to meet the complicated situations in heterogenous network. International Standard Organization and Motion Picture Expert Group published scalable video coding standard so as to solve the problems raised by various bandwidth and different terminals in heterogenous network.In the process of standardizing scalable video coding, wavelet transform was not adopted in the international standard, since it cannot bring about coding performance that matches its complexity. However, wavelet transform is thought as an ideal tool of scalable video coding all the time due to its multiresoluton property, and is being researched. STP(Spatio-Temporal subbands Prediction)-tool scheme in generated signals/subbands perspective was proposed as wavelet-based scalable video coding framework. And also barbell lifting scheme is used to achieve motion compensation temporal filtering. They provide good solutions to the problems in fractional-pixel accuracy mapping and multi-to-multi mapping in motion compensation.On the basis of barbell lifting, the thesis gives an improved barbell lifting function and two neighbourhood-pixel schemes, and a weight distribution scheme which matches them in order to achieve barbell lifting scheme and apply it into wavelet-based scalable video encoder. In concrete implementation, in order to take into account the coding efficiency and performance of barbell lifting, macroblock-level weight coefficients scheme and frame-level neighbourhood-pixel scheme are employed, achieving fairly well compression performance and scalability. |
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