The Key Technology Implementation For XAVS Encoder

AVS is the second-generation encoding standard of China with independent intellectual property. It obtains equivalent encoding performance comparing to H.264 with low implementation complexity. Once commercial, the status will be changed that the related enterprises in China are long-term subject to standardization of patented technology held by foreign enterprises and organizations. It is a huge impetus to the development of Chinese information industry and will also save billions of dollars in annual patent fees.Although the current AVS decoder already have more mature development, but as an important link in the chain of AVS, encoder still hasn't perfect product to achieve, which restricts the process of industrialization of AVS. So the way to resolve this issue that developing a high performance AVS encoder. xAVS is the open-source software tasks proposed by AVS Working Group in March 2009. The AVS encoder for AVS P2 runs on the x86 processor platforms, and features optimized for x86 processors. It requires supporting IPPP, IBBP structure, films on a variety of formats of media sources to AVS compression, rate control, rate distortion optimization, and packaged into the standard TS stream. Taiyuan University of Technology is responsible for the project implementation and Peking University and Chang hong company are responsible for the project test. As a member of the group, the paper completes the following work:In-depth study the criteria algorithm of AVS; design the framework for all I frame encoder of xAVS; make various structures initialization, allocate the necessary memory space and design the interface of others modules for the subsequent integration. Design the writing stream, intra prediction, transform and quantization, entropy encoding and loop filter modules for xAVS all I frame encoder. Ensure the correctness of the modules and integrate the modules to guarantee xAVS all I frame encoder correctness by debugging. Under the same conditions, the objective quality and bit rate of xAVS all I frame encoder is considerable to that of rm52j, but the encoding speed of xAVS all I frame encoder is more than 12 fps higher than that of rm52j and the subjective image quality of xAVS is superior to that of rm52j.Be very familiar with the characteristics of multimedia instruction set, and stay out of the interface of multimedia instruction set (MMX, SSE2) in writing c code. For cif format sequence, the encoding average speed is about the 19 frame per second (fps) for pure c under xAVS all I frame encoder. When using sad, satd and ssd multimedia instruction set, the encoding average speed can reach real-time, and the encoding average speed for inter-encoded also increases more than 6fps. Upon completion of I, P, B structure, supports encoding films on a variety of formats of media sources; realize rate control (RC) algorithm based on the complexity and xAVS supports constant bit rate, variable bit rate, constant quality, The average bit rate, the second code and constant QP rate control; design and implement AVS rate-distortion optimization (RDO) algorithm. The best Lagrange coefficient is selected by a large number of experiments to improve the subjective and objective quality xAVS encoder, and reduce the bit rate. Comparing with not using RDO, After conducting RDO, for IBBP structure, the luminance PSNR of xAVS enhances 0.28dB, the chroma U enhances 0.29dB, the chroma V enhances 0.33dB and the bit rate reduces 3.79%.The project has been identified by expert groups that Shanxi Science and Technology Department organized, and has reached the "international advanced level." The work still needs further optimization and improvement. The implementation of xAVS promote to Internet applications and has important significant for the development of the Chinese multimedia industry.