Majid Ardestani

PhD Thesis Defense Session

Abstract:
Multiple description scalable coding based on T+2D wavelet decomposition provides a flexible structure for peer-to-peer video streaming with lossy links and heterogeneous nodes. In the present thesis, two different strategies are proposed; one based on segmentation and unequal loss protection of the embedded video bit stream and another based on truncation of the scalable bit stream of each code block. In the first strategy, it is important to find the suboptimal sizes of the bit stream segments. To this end, an analytical relation is found between the optimal sizes of any two successive segments which is the result of analysis of the optimization cost function around the optimal point and smart search of the state space. This idea yields a progressive solution with low computational complexity and identical performance as the local search algorithm.
In the second strategy, it is necessary to find the optimal truncation point of each code block within each description. This is a complicated problem requiring a full search in a huge dimensional state space. To design an adaptive low-complexity encoder with arbitrarily unbalanced descriptions, a simple clustering algorithm is proposed for partitioning the CBs into a limited number of clusters. This simple and efficient clustering algorithm significantly reduces the size of redundancy-rate assignment matrix, such that one can find the optimal channel-aware cluster-level redundancy-rate assignment matrix using a low-complexity full search approach. This approach improves the decoding quality compared to the co-echelon adaptive frameworks. In addition, the proposed clustering approach (along with an experimental rate-distortion modeling) may be analytically represented by closed-form relations for low-complexity computation of the optimal encoding parameters. Therefore, an efficient real-time post-encoding adaptation mechanism may be realized.

: Date of Defense
Sunday, September 11, 2011
Classroom No. 302, Faculty of Electrical Engineering