A New Fast PU Partition Mode Decision Algorithm For HEVC

With the rapid development of digital video applications, the development trend of video applications is becoming more obvious in the following directions: higher definition, higher compression rate and higher frame rate. However, the current hardware platform and limited transmission bandwidth are hard to meet the needs of video applications,H.264/AVC standard may not meet the demand of high quality and high resolution video compression. So High Efficiency Video Coding Standard arises at the historic moment. High Efficiency Video Coding(HEVC) is a next generation standard that is developed jointly by ITU-T and ISO/IEC. It applied not only in high-definition video but also in more widely field.To achieve higher coding efficiency, HEVC reserved the framework of traditional video coding and adopted some newest technology about video coding field. As a result, the performance is two times as the H.264/AVC standard. It employs a flexible block partition structure, including coding unit(CU), transform unit(TU) and prediction unit(PU).HEVC and adopts a new inter PU partition mode: merge mode, which makes prediction more accurate. Besides, HEVC adds SAO after de-blocking filter, which reduces distortion between original picture and constructed picture. However, the improvement in compression performance brought huge coding complexity. So fast algorithms must be proposed to reduce coding complexity and save encoding time.Video sequences consist of many continuous static images, so there is high correlation between two neighboring frames. In this paper, considering the relativity between the neighboring frames, using the encoding information of Co-located CU can effectively predict prediction unit(PU) partition mode of current coding unit(CU). The correlation of PU partition modes between Co-located CU and current CU in slow motion and moderate motion are analyzed, and then PU partition mode candidates are set according to the correlation probability. Then choose PU partition modes from PU partition mode candidates to encode video sequences which skip redundant partition modes.So the complexity is reduced and the encoding time is decreased. The simulation result indicates that with nearly the same BD-PSNR, this method saves the coding time by 4.69% in low-delay configuration and 8.43% in random-access configuration contrast to CFM, 13.81% in low-delay configuration and 15.88% in random-access configuration contrast to ESD, and 4.22% in random-access configuration contrast to Lee.