Research On Key Techniques For Multi-view Video Coding

With the development of compute graphics and computer vision technology, multi-view video attracts more and more attention. Compared with the traditional single-view video, multi-view video comprises rich three-dimensional depth information, which can provide people with the highly-welcome experience of3D stereoscopic and interactive. However, multi-view video is captured by a set of video cameras from various viewpoints but at the same time. With the increasing number of cameras, the amount of video data is linearly increased. Huge amount of video data highly requires for efficient storage and transmission. Multi-view video coding is efficient compression for multi-view video data. With the advances in the new display and network transmission techniques, multi-view video coding attracts more and more attention.MVC follows the classic block-based hybrid video coding framework, and the development and innovation of the framework. Intricate prediction structure brings out rapid increase in computational complexity, which obstructs MVC from practical application and promotion. Therefore, it is very essential for MVC to study low complexity fast algorithms. In MVV, it is also with inter-view correlation between different views but at the same time instant, besides spatial correlation and temporal correlation within a single view. Hence, the key of speeding up encoding for MVC is how to effectively utilize these correlations within a sigle view and between views to remove the redundancy. This research paper dedicates much effort to series of optimizations for those time-consuming modules of MVC, based on the analysis for the key techniques of MVC.First, an efficient early Direct mode decision for MVC is proposed in order to overcome heavy computation of mode analysis, on the basis of analyzing each mode of MVC. Based on the observation that the Direct mode is highly possible to be the optimal mode, the proposed method first computes the rate distortion cost of the Direct mode of the current macroblock and compares this RD cost value with an adaptive threshold for providing an early termination chance as follows. If this RD cost value is smaller than the adaptive threshold, the Direct mode will be selectd as the optimal mode and the checking process of remaining modes will be skipped; otherwise, exhaustive mode decision is used to check all the modes to select the optimal mode. The key of the proposed algorithm is the design of the adaptive threshold, which is determined by using the spatial, temporal and inter-view correlations between the current macroblock and its neighboring macroblocks, respectively. Experimental results have shown that the proposed method is able to reduce the computational load by72.38%and the total bit rate by1.06%, while only incurring a negligible loss of PSNR (about0.05dB on average), compared with exhaustive mode decision in the reference software of MVC.Second, a fast inter prediction algorithm based on mode complexity for multi-view video coding is proposed, after analyzing the characteristic of each variable block size in inter prediction of the MVC. In the proposed algorithm, macroblocks are divided into three different mode classes on the basis of the mode complexity defined. Each class only checks the specified mode size(s), and the other unnecessary mode sizes can be early terminated. Thus, computational load can be greatly reduced. Experimental results have demonstrated that the proposed method is able to reduce62.75%with negligible loss of coding efficiency, compared with the full mode decision in the reference software of MVC.Third, a fast inter-view prediction algorithm based on an early disparity estimation skipping is presented aim at impoving the prediction efficiency between inter-views for MVC. This method is proposed via using prediction direction correlation between inter mode sizes. The prediction result of mode16×16selecting inter-view prediction as its optimal prediction can be used to decide whether disparity estimation of the other mode sizes is selected or not. Experimental results have shown that the proposed method can omit the unnecessary disparity estimation process, and effectively reduce the computational complexity in inter-view prediction for MVC.Finally, a fusion algorithm is proposed based on the above-mentioned algorithms. This algorithm combines the Direct mode early termination, variable size inter prediction and early disparity estimation skipping. Experimental results have shown that the fusion algorithm is able to significantly reduce the computational complexity of MVC by78.79%on average and the total bit rate by0.07%on average, while only incurring a negligible loss of PSNR (about0.04dB on average), compared with exhaustive mode decision in the reference software of MVC.In summary, the key techniques in multi-view video coding are analyzed in this paper, and the optimizations of the corresponding modules are studied. The proposed fast optimization algorithms can significantly reduce the computational complexity of MVC,which has an important reference value to the practical applications of MVC...