一种基于H.264/AVC的高效块匹配搜索算法

本文针对H.264/AVC的编码特点,提出了一种利用时空域运动相关性的快速块匹配搜索算法.该算法充分利用了视频序列的运动程度与宏块编码模式间的关联特性以及运动矢量的统计特征,明显减少了运动估计的搜索复杂度.实验表明,本文方法的搜索速度分别比FS和DS算法平均提高了77.96%和32.19%;重建图像的PSNR比DS算法平均提高了0.06dB,更接近FS算法的编码质量.     

An SAD‐Based Selective Bi‐prediction Method for Fast Motion Estimation in High Efficiency Video Coding

As the next‐generation video coding standard, High Efficiency Video Coding (HEVC) has adopted advanced coding tools despite the increase in computational complexity. In this paper, we propose a selective bi‐prediction method to reduce the encoding complexity of HEVC. The proposed method evaluates the statistical property of the sum of absolute differences in the motion estimation process and determines whether bi‐prediction is performed. A performance comparison of the complexity reduction is provided to show the effectiveness of the proposed method compared to the HEVC test model version 4.0. On average, 50% of the bi‐prediction time can be reduced by the proposed method, while maintaining a negligible bit increment and a minimal loss of image quality.     

Improved motion estimation time using a combination of dynamic reference frame selection and residue-based mode decision

Motion estimation using multiple reference frames is widely used as the basis for recent video coding standards (eg. H.264/AVC) to achieve increased coding efficiency. However, this increases the complexity of the encoding process. In this paper, a new technique for efficient motion estimation is proposed. A combination of multiple reference frame selection and image residue-based mode selection is used to improve motion estimation time. By dynamic selection of an initial reference frame in advance, the number of reference frames to be considered is reduced. In addition, from examination of the residue between the current block and reconstructed blocks in preceding frames, variable block size mode decisions are made. Modified initial motion vector estimation and early stop condition detection are also adopted to speed up the motion estimation procedure. Experimental results compare the performance of the proposed algorithm with a state of the art motion estimation algorithm and demonstrate significantly reduced motion estimation time while maintaining PSNR performance.     

基于块金字塔的快速块匹配算法

在运动图象编码中，块匹配技术有着非常广泛的应用。在众多的匹配算法中，金字塔算法(blocks sum pyramid algorithm，BSPA)由于速度较快、算法比较简单而得到了广泛的应用。在金字塔算法的基础上，本文提出一种新的基于块金字塔的块匹配算法(NBSPA)。算法采用了预测初始中心，行更新等技术，实验结果表明，新的算法有效地降低了运算量。     

基于时域相关性的HEVC快速帧内预测算法

根据视频序列时域相关性强的特性,提出了一种基于时域的HEVC快速帧内预测算法。在帧间预测中,通过在参考帧中运动搜索找到当前预测单元(PU)的帧间最佳匹配块,当搜索当前PU的帧内预测模式时,把帧间最匹配参考块遍历帧内模式时的最佳帧内模式,当作当前PU进行帧内预测时的最佳帧内模式,以达到减少帧内预测模式数量,降低计算复杂度的目的。实验结果表明,在码率和图像质量基本不变的情况下,提出的算法将HEVC帧内预测时间平均减少了33.79%。     

Fast coding unit partitioning method based on edge detection for HEVC intra-coding

High efficiency video coding (HEVC) standard is the latest video coding standard generation. It employs powerful coding tools to obtain improved compression efficiency. To better exploit the redundancies, HEVC adopts a very flexible quad-tree coding structure, allowing the encoder to use a block partition that matches the image features. This exhaustive technique may achieve a higher coding efficiency; however, it induces a significant computational complexity in the encoding engine. This paper proposes a new texture parameter for classifying digital videos as a first contribution and then introduces an efficient coding unit (CU) partitioning algorithm based on the early defined texture parameter in order to speed up the encoding process. In fact, the proposed technique is based on edge detection by performing SOBEL filtering in order to decide the appropriate CU size. Compared to the original HEVC, the average execution time-saving is about 31 % while maintaining almost the same output video quality.     

Fast motion and disparity estimation for HEVC based 3D video coding

The emerging international standard for high efficiency video coding (HEVC) based 3D video coding (3D-HEVC) is an extension of HEVC. In the test model of 3D-HEVC, variable size motion estimation (ME) and disparity estimation (DE) are both employed to select the best coding mode for each treeblock in the encoding process. This technique achieves the highest possible coding efficiency, but it brings extremely high computational complexity which limits 3D-HEVC from practical applications. In this paper, a fast ME/DE algorithm based on inter-view and spatial correlations is proposed to reduce 3D-HEVC computational complexity. Since the multi-view videos represent the same scene with similar characteristic, there is a high correlation among the coding information from inter-view prediction. Besides, the homogeneous regions in texture video have a strong spatial correlation, and thus spatially neighboring treeblocks have similar coding information. Therefore, we can determine ME search range and skip some specific ME and DE rarely used in the previously coded view frames and spatially neighboring coding unit. Experimental results demonstrate that the proposed algorithm can significantly reduce computational complexity of 3D-HEVC encoding while maintaining almost the same rate-distortion performance.     

Content-Aware Fast Motion Estimation Algorithm

In this paper, we propose the Content-Aware Fast Motion Estimation Algorithm (CAFME) that can reduce computation complexity of motion estimation (ME) in H.264/AVC while maintaining almost the same coding efficiency. Motion estimation can be divided into two phases: searching phase and matching phase. In searching phase, we propose the Simple Dynamic Search Range Algorithm (SDSR) based on video characteristics to reduce the number of search points (SP). In matching phase, we integrate the Successive Elimination Algorithm (SEA) and the integral frame to develop a new SEA for H.264/AVC video compression standard, called Successive Elimination Algorithm with Integral Frame (SEAIF). Besides, we also propose the Early Termination Algorithm (ETA) to early terminate the motion estimation of current block.We implement the proposed algorithm in the reference software JM9.4 of H.264/AVC and the experimental results show that our proposed algorithm can reduce the number of search points about 93.1%, encoding time about 42%, while maintaining almost the same bitrate and PSNR.     

A Modified Block Matching Motion Estimation Algorithm for the Very Low Bit-Rate video Coding

1IntroductionMohonestimationplaysanimportantroleindigitalvideocompression.Block-matchingtechniquehasbeenadoptedinmanyvideocompressionstandardssuchasH.261,MPEG-l,MPEG-2andH.263.Eventhoughthealgorithmtoestimatethemotionvectorsisnotspecifiedexplicitly.However,despiteitssuccessfulapplications,itproducesarathernoisyinchonfield.Inverylowbit-ratevideocodingapplications,theamountofthesideinformationfortheinchonfieldrepresentsanimPOrtantportionofthetotalbit-rate.Therefore,motionestimatetechniques…     

Edge oriented block motion estimation for video coding

Intensity-based block motion estimation and compensation algorithms are widely used to exploit temporal redundancies in video coding, although they suffer from several drawbacks. One of the problems is that blocks located on boundaries of moving objects are not estimated accurately. It causes poor motion-compensated prediction along the moving edges to which the human visual system is very sensitive. By considering the characteristics of block motions for typical image sequences, an intelligent classifier is proposed to separate blocks containing moving edges to improve on conventional intensity-based block matching approaches. The motion vectors of these blocks are computed using edge matching techniques, so that the motion-compensated frames are tied more closely to the physical features. The proposed method can then make use of this accurate motion information for edge blocks to compute the remaining non-edged blocks. Consequently, a fast and efficient block motion estimation algorithm is developed. Experimental results show that this approach gives a significant improvement in accuracy for motion-compensated frames and computational complexity, in comparison with the traditional intensity-based block motion estimation methods     

一种基于零块分布的快速帧间模式判决算法

针对新一代视频编码标准离散视编码(HEVC)帧间预 测编码计算复杂度过高的问题,提出一种利用变换量化 后零块分布特征进行快速帧间模式筛选的低复杂度算法。首先统计SKIP和帧间 2N×2N模式下零系数与 非零系数的区域分布特征,判断其运动特征和运动估计匹配效果,用以分析全零块下SKIP 模式的分布;同 时在非全零块下结合残差块的SATD代价分类筛选PU模式分布,从而优先选择符合零块分布 特征的PU 模式,以达到快速筛选帧间模式,降低计算复杂度的效果。实验结果表明,在低延迟和随机 访问配置条件下,本文提出的算法在保证编码性能的情况下,相比原有HM 快速算法, 编码时间平均分别可减少50.3和49.3%,BDBR仅降低0.03%,有效 地降低了编码复杂度。     

Background foreground boundary aware efficient motion search for surveillance videos

The huge amount of data in surveillance video coding demands high compression rates with lower computational requirements for efficient storage and archival. The motion estimation is a very time-consuming process in the traditional video coding framework, and hence reducing computational complexity is a pressing task, especially for surveillance videos. The presence of significant background proportion in surveillance videos makes its special case for coding. The existing surveillance video coding methods propose separate search mechanisms for background and foreground regions. However, they still suffer from misclassification and inefficient search strategies since it does not consider the inherent motion characteristics of the foreground regions. In this paper, a background-foreground-boundary aware block matching algorithm is proposed to exploit special characteristics of the surveillance videos. A novel three-step framework is proposed for boundary aware block matching process. For this, firstly, the blocks are categorized into three classes, namely, background, foreground, and boundary blocks. Secondly, the motion search is performed by employing different search strategies for each class. The zero-motion vector-based search is employed for background blocks. Whereas, to exploit fast and directional motion characteristics of the boundary and foreground blocks, the eight rotating uni-wing diamond search patterns are proposed. Thirdly, the speed-up is achieved through the novel region-based sub-sampled structure. The experimental results demonstrate that two to four times speed-up over existing methods can be achieved through this scheme while maintaining better matching accuracy.     

Parallel spiral search algorithm applied to integer motion estimation

Thanks to its flexible coding structure, high-efficiency video coding (HEVC) can save more coding bit rates than the previous standard, H.264. However, it also increases the complexity of integer-pixel motion estimation (IME). To speed up the encoding process, we propose a parallel spiral search (PSS) algorithm, which features the following characteristics and advantages. First, the proposed algorithm is hardware-friendly. PSS has both a fix search order that cuts the correlation between search points and a high data reuse level that facilitates the pipeline application in hardware implementation. Second, the PSS algorithm processes all prediction units (PU) blocks in parallel, which speeds up the RD calculation. Finally, the early termination strategy is proposed to end the search for unnecessary search points and further reduce search time. Experimental results show that the proposed algorithm outperforms other popular hardware-oriented IME algorithms in terms of coding speed, with the same loss of RD performance. Compared with the default full search algorithm (FSA) in the HEVC test model HM-16.7, the proposed algorithm achieves average time saving ratio of up to 92.55%, with BD-PSNR loss of 0.056 dB and an increase by 1.38% in terms of BD-BR.     

一种基于硬件实现的快速运动估计半像素级搜索算法

研究了在绝对差和准则下的整像素级块匹配和半像素级块匹配的联系，对绝对差和进行了合理的数学曲线拟合，通过数学曲线来预测最小绝对差和所在半像素位置，从而得到半像素级最佳匹配矢量。分析了三种不同的凹函数预测模型，提出了一种适合硬件实现的运动估计快速半像素级搜索算法。该算法直接根据整像素级运动估计的结果来推算半像素级运动估计结果，在很大程度上降低了半像素级运动估计的运算复杂度，从而利用低码率视频编码的实时实现。试验结果表明该算法可获得较好的重建图像质量。该算法利于硬件实现，可以方便地集成到现有的视频编码器中，具有较好的实用价值。     

Adaptive block matching algorithm for video compression

A simple adaptive block matching algorithm for video coding is presented. In the proposed algorithm, a matching criterion called bit-plane matching is proposed to sort out a number of blocks with unlikely directive information to the test block from the search window. An adaptive searching method is developed to further improve the computational effectiveness of the system. In this searching method the search origin, search range and pixel subsampling ratio can be adjusted according to the motion content of the block. Simulation results show that the proposed algorithm achieves MSE performance to the full-search and about 92-95% savings in computation     

基于视点相关性的光场图像压缩算法

为了探索虚拟绘制视点之间的强相关性, 提高光场图像的压缩效率, 提出一种基于视点相关性的光场图像压缩算法。该算法基于高清视频编码屏幕内容编码扩展平台, 利用线性加权算法以及帧内块拷贝混合预测算法来提升编码块的预测精度; 并利用率失真优化过程来自适应地选择最优的编码块大小以及预测模式。结果表明, 所提算法相比于高清视频编码标准可以获得2.55dB的平均BD-峰值信噪比编码增益, 同时可以获得较好的虚拟视点绘制质量。该算法充分利用虚拟绘制视点之间的强相关性, 提高了光场图像的编码效率。     

Efficient Inter Prediction Mode Decision Method for Fast Motion Estimation in High Efficiency Video Coding

High Efficiency Video Coding (HEVC) is the most recent video coding standard to achieve a higher coding performance than the previous H.264/AVC. In order to accomplish this improved coding performance, HEVC adopted several advanced coding tools; however, these cause heavy computational complexity. Similar to previous video coding standards, motion estimation (ME) of HEVC requires the most computational complexity; this is because ME is conducted for three inter prediction modes — namely, uniprediction in list 0, uniprediction in list 1, and biprediction. In this paper, we propose an efficient inter prediction mode (EIPM) decision method to reduce the complexity of ME. The proposed EIPM method computes the priority of all inter prediction modes and performs ME only on a selected inter prediction mode. Experimental results show that the proposed method reduces computational complexity arising from ME by up to 51.76% and achieves near similar coding performance compared to HEVC test model version 10.1.     

BIT-CORRELATION MATCHING FUNCTION FOR IMAGE SEQUENCE CODING

This paper proposes a new block matching criterion called the bit-correlation matching function for image sequence coding. When using the identical fast searching algorithm, the bit-correlation matching function not only results in nearly the same accuracy in displacement estimation as the mean square error function, but also makes the algorithm low in computation complexity and easy to parallel implementation, thus reducing the coding time of image sequence efficiently.     

自适应联合相邻运动矢量的运动补偿插值算法

帧率上采样作为一种视频后处理技术,通过对原始视频插值得到高帧率视频,满足人们对高帧率视频的需求.传统基于重叠块的插值补偿算法会带来块效应或鬼影现象.为了解决这一问题,人们提出联合匹配块及其相邻块预测的方法,但是复杂度高,效果不明显.基于以上几点,本文提出一种自适应联合相邻运动矢量的运动补偿插值算法(Joint Motion-Compensated In-terpolation Algorithm Using Adjacent Block Motion Vectors Adaptively,AJ-MCI).在该算法中,将运动矢量矫正和运动补偿插值算法相结合,同时运动补偿模块中自适应地联合相邻匹配块,以最大限度刻画真实运动轨迹.实验结果表明,本文算法能很好的提升视频的主客观质量,同时保持较低计算复杂度.     

Conservative Approximation–Based Full‐Search Block Matching Algorithm Architecture for QCIF Digital Video Employing Systolic Array Architecture

This paper presents a power‐efficient hardware realization for a motion estimation technique that is based on the full‐search block matching algorithm (FSBMA). The considered input is the quarter common intermediate format of digital video. The mean of absolute difference (MAD) is the distortion criteria employed for the block matching process. The conventional architecture considered for the hardware realization of FSBMA is that of the shift register–based 2‐D systolic array. For this architecture, a conservative approximation technique is adapted to eliminate unnecessary MAD computations involved in the block matching process. Upon introducing the technique to the conventional architecture, the power and complexity of its implantation is reduced, while the accuracy of the motion vector extracted from the block matching process is preserved. The proposed architecture is verified for its functional specifications. A performance evaluation of the proposed architecture is carried out using parameters such as power, area, operating frequency, and efficiency.