In HEVC (High Efficiency Video Coding), linear interpolation of the boundary pixels is used as the predictor and pixels within the same PU (Prediction Unit) are in the same prediction direction. When the PU block is large and in high complexity, the prediction performance would worsen. Although many algorithms use the pixel-based weighted averaging or interpolation operations to perform the prediction which improves the performance of bitrate saving notably, there is still space for further improvement. This paper proposed an improved SAP (Sample-based Angular Prediction) algorithm based on adaptive directional prediction (ADSAP). The innovation of this paper lies in two aspects: it puts forward a new method to estimate the best prediction direction of current pixel and it introduces the concept of "frame-level pretreatment" which could greatly improve the encoding speed. Experimental results show that it could save the output bitrate by about 9.4158% when compared with the HEVC lossless intra prediction algorithm, which is better than other typical algorithms. Besides, the encoding and decoding time are reduced by about 11%. Moreover, when the minimum PU size gets larger, the increase of output bitrate of ADSAP is much less than that of HEVC and the conventional SAP algorithm, which makes the proposed algorithm quite suitable for the compression of high resolution videos. (C) 2015 Elsevier Inc. All rights reserved.
Science & Technology
Computer Science, Information Systems
; Computer Science, Software Engineering
1.Chinese Acad Sci, Inst Opt & Elect, Chengdu 610209, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Chengdu Normal Univ, Chengdu 610072, Peoples R China
Xia, Xiao-Peng,Liu, En-Hai,Qin, Jun-Ju. Improved SAP based on adaptive directional prediction for HEVC lossless intra prediction[J]. JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION,2015,33:78-84.