| Video applications are trending towards to the high quality and real-time performance. High definition video has been widely used in radio and television, video conference, streaming media service and other aspects. On the other hand, the video service based on the heterogeneous networks is of high demand too. High definition and heterogeneous adaptability have been the key words of video technology, which is along with the other two problems of video technology:the first one is the compression of efficient of HD or Ultra-HD video; the second is the adaptability of output stream to the heterogeneous network and variable intelligent terminals. With such opportunities and challenges, scalable video coding becomes a possible effective solution to the application requirements of HD video. Although scalable coding technology has lots of advantages such as well adaptability to terminals and networks, simple implementation of decoder, and high coding efficiency, its coding complexity, especially in high definition video application, still restraints it being widely used. Therefore, this paper researched the fast coding algorithms to reduce the coding complexity based on the H.264/SVC standards for HD video. The main contributions of this paper can be concluded as follows:1. Studied the key technologies of scalable coding based on H.264/SVC, including the technologies of temporal, spatial and quality scalability. It also introduced the low complexity coding algorithm and fast search algorithm used in SVC (Scalable Video Coding). The coding efficiency of low complexity algorithm was also analyzed, it indicates the low complexity encoding algorithm can improve the coding speed; it also greatly decreased the coding efficiency.2. Besides of the statistic conditional best mode of inter prediction frequency distribution, this paper also analyzed the rate distortion cost probability distributions for each conditional best mode of high used frequency. Base on that statistic result, this paper proposed a model to calculate the earlier termination threshold using the quantizing parameter and estimated picture complexity. Test results show that the proposed fast inter prediction algorithm can speed up the encoder by 45%, with bit rate of the highest layer (HD layer) increase less than 1%.3. Proposed the fast intra prediction algorithm for SVC. Base on the statistic conditional best mode of intra prediction frequency distribution, the algorithm first optimized the coding flow of intra prediction. It also proposed a fast coding algorithm for inter-layer intra prediction process using Hardamard transformation results of residual between layers. The algorithm can not only speed up but also can optimize the encoder performance. Test results show that the combined algorithm can save 40% of the encode time on average, and get 1.19% gain in bit rate.4. Reviewed the latest progress of next generation high efficiency coding (HEVC), and presented the test results of it. It also looked forward into the development of scalability for HEVC, and indicated the next step of work. |
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