Research On The Optimization Of Intra And Inter Mode Decision Method In HEVC

As the requirement of the digital video service in quality and resolution is higher and higher, the high definition TV adapting to larger screen and higher resolution is born to meet this requirement. Since there are a lot of pixels in a high resolution video, the H.264 video compression standard is inefficient to compress this kind of video. To reduce the storage space and transmission bandwidth of the high resolution video, the experts in MPEG and VCEG jointly developed the newest video compression standard, named as the HEVC, for the compression of the high resolution videos.HEVC standard has employed the techniques of lager encoding units, unsymmetrical block size, variable block division length, more prediction directions, etc., to improve the compression efficiency. The objective of this standard is to reduce more than 50% bit rate of the H.264 while having acceptable complexity. However, the set of the encoding parameters of this standard is much larger than previous standards, and the process to decide good encoding parameters becomes more complex and needs more execution time, which hinders the implementation and applications of the HEVC standard. Thus, a fast algorithm to decide relatively good encoding parameters for HEVC is crucial and is the object of this thesis. The work of this thesis is listed in the following.(1) A brief introduction of the previous MPEG-x and H.26x standards is firstly given. Then, the research backgrounds and importance are overviewed. After that, the structure of this thesis is listed.(2) Then, the analysis of the various modules of the HEVC encoder is conducted and the modules which have a large influence on the execution time of the encoder is pointed out. It is found that the modules of the estimation of the optimal prediction angle in the intra coding mode, and the complexity of the search patterns used in the TZSearch algorithm for the motion estimation are the main factors for the time execution of the encoder.(3) For this reason, a new and fast intra mode decision algorithm is proposed for the mode selection in the Intra code mode of the HEVC. This algorithm is based on the Hough transform. On average, this algorithm can reduce the overall 35 times to check all the prediction modes. The proposed algorithm can accelerate the execution of the HEVC and can have a bright future for the high resolution and big size frame applications.(4) The new feature of the motion estimation of the HEVC is analyzed. A new and fast algorithm is proposed for the fast motion estimation of the HEVC. The search patterns of the TZSearch are improved to reduce the average search times used for the optimal reference block search.