Research On Fast Inter Frame Algorithms For High Efficiency Video Coding

As people have higher and higher requirements for video quality,video coding technology is constantly being improved.At present,the high efficiency video coding standard H.265/HEVC is the mainstream video coding standard.Comparing with the H.264/AVC standard,although the H.265/HEVC standard has a 50% reduction in bit rate,the computational complexity of the H.265/HEVC standard is increased by dozens of times over H.264/AVC under the same image quality.Therefore,based on the H.265/HEVC standard,it is difficult to achieve real-time applications such as monitoring.Inter prediction is one of the important components of video coding,which mainly includes motion estimation and mode decision.This paper analyzes the process of inter prediction,and respectively proposes new fast algorithms for two parts of motion estimation and mode decision in order to remove the redundant information and reduce the computational complexity.In the motion estimation,the integer pixel motion estimation and the fractional pixel motion estimation are studied separately.In the integer pixel motion estimation,a new hybrid search model is proposed from the aspect of search strategy,and the threshold is set based on the rate distortion cost to control the switching between the search models,thereby searching the optimal integer pixel more efficiently.With almost no change in video quality,the encoding time of this algorithm is 8.58% lower than the reference algorithm.In the fractional pixel motion estimation,a new fast search algorithm is proposed from two aspects of the search strategy and the calculation of the rate distortion cost.The concept of sub-optimal 1/2 pixel is introduced,and the search range of the optimal 1/4pixel is determined by the optimal 1/2 pixels and sub-optimal 1/2 pixels.This algorithm reduces the number of search points,removes time redundancy,and improves codingefficiency.Compared with the reference algorithm,the proposed algorithm can the save about 26.30% of coding time with only about 0.51% bit rate increase.In the mode decision of the inter prediction unit,an early termination algorithm is proposed from the aspect of the rate distortion cost.The early termination algorithm has two levels of termination meaning.The first termination means the determination of the SKIP mode.If the conditions are met,the algorithm is terminated directly.The second termination refers that the threshold is used to determine whether to terminate the algorithm without going through the redundant mode.With almost no change in video quality,the coding time is saved by 30.11%.In the process of the mode decision,the texture complexity of the video image is analyzed,and an fast inter prediction unit mode decision algorithm is proposed from the aspect of the texture complexity.Depending on whether the video texture is horizontal or vertical,the mode is traversed selectively without going through all the modes.Compared with the mode decision algorithm in HEVC,the proposed algorithm can save 34.18% of coding time and reduce 0.04 d B of the peak-signal-to-noise ratio with only about 0.74% bit rate increase.