Novel two-layer motion estimation for video coding

In this paper,we proposed a novel Two-layer Motion Estimation （TME） which searches motion vectors on two layers with partial distortion measures in order to reduce the overwhelming computational complexity of Motion Estimation （ME） in video coding.A layer is an image which is derived from the reference frame such that the sum of a block of pixels in the reference frame determines the point of a layer.It has been noticed on different video sequences that many motion vectors on the layers are the same as those searched on the reference frame.The proposed TME performs a coarse search on the first layer to identify the small region in which the best candidate block is likely to be positioned and then perform local refined search on the next layer to pick the best candidate block in the located small area.The key feature of TME is its flexibility of mixing with any fast search algorithm.Experimental results on a wide variety of video sequences show that the proposed algorithm has achieved both fast speed and good motion prediction quality when compared to well known as well as the state-of-the-art fast block matching algorithms.     

一种起点预测的十字形快速运动估计算法

基于时运动矢量概率分布的方向性中心偏移特性和起点预测搜索技术的研究,提出了一种起点预测的十字形快速运动估计算法(IPPAFA),在保持搜索精度的同时有效降低了计算复杂度。实验结果表明,在图像质量几乎不下降的情况下,与钻石搜索算法(DS)和运动矢量场自适应搜索算法(MVFAST)相比,该算法在速度和准确性方面都优于传统的快速运动估计算法。     

改进的空间下采样视频转码快速运动估计算法

提出一种基于输入码流信息和已转码码流信息的视频转码快速运动估计算法。本算法利用Alpha-激励均值滤波通过输入码流的运动矢量合成作为备选预测运动矢量之一,并利用H．264标准中帧间预测的方法通过已转码码流信息合成另一个备选预测运动矢量,共同作为EPZS运动估计算法的预测中心。结合图像的运动活跃性．自适应的调整运动估计的搜索策略。该算法比传统的运动矢量方法相比提高了1dB左右的PSNR,保持了较高的转码图像质量并与菱形搜索算法相比能够降低18％左右的转码时间。     

运动补偿在等离子体显示屏中的应用

等离子体显示屏在显示运动画面时会出现伪轮廓线等动态失真现象。一种解决方法是对子场显示信息进行运动补偿，但它需要对连续视频流进行准确运动估计。本文提出一种MPEG码流中运动矢量提取算法，并对运动矢量提取方法和全搜索块匹配法进行了比较。利用提取的运动矢量，讨论了部分子场运动补偿方法对等离子体显示屏图像质量的改进。仿真结果表明将运动矢量提取方法和部分子场补偿方法相结合可以明显的消除等离子体显示屏上的动态失真现象。     

An efficient gray search algorithm for the estimation of motionvectors

Motion vector estimation plays an important role in motion-compensated video coding. An efficient and fast search algorithm is proposed for the estimation of motion vectors. With the help of gray prediction, the algorithm can determine the motion vectors of image blocks quickly and correctly. Since the proposed algorithm performs better than other search algorithms [e.g. the three-step search (TSS), cross-search (CS), new three-step search (NTSS), four-step search (FSS), block-based gradient descent search (BBGDS), simple-and-efficient search (SES), prediction search (PS) and gray prediction search (GPS)], it is very beneficial in applications where the video coding speed is important     

A variable block size motion estimation algorithm for real-time H.264 video encoding

This paper presents an efficient variable block size motion estimation algorithm for use in real-time H.264 video encoder implementation. In this recursive motion estimation algorithm, results of variable block size modes and motion vectors previously obtained for neighboring macroblocks are used in determining the best mode and motion vectors for encoding the current macroblock. Considering only a limited number of well chosen candidates helps reduce the computational complexity drastically. An additional fine search stage to refine the initially selected motion vector enhances the motion estimator accuracy and SNR performance to a value close to that of full search algorithm. The proposed methods result in over 80% reduction in the encoding time over full search reference implementation and around 55% improvement in the encoding time over the fast motion estimation algorithm (FME) of the reference implementation. The average SNR and compression performance do not show significant difference from the reference implementation. Results based on a number of video sequences are presented to demonstrate the advantage of using the proposed motion estimation technique.     

一种预测质量可控的快速运动估计搜索算法

本文提出了一种预测质量可控的快速运动估计搜索算法.该算法利用运动矢量的空间、时间相关性,通过预测初始搜索中心位置、判定是否为静止宏块、调整搜索窗口、预测质量可控的渐进式块匹配准则搜索等步骤进行运动估计,并引入调节函数在预测质量和搜索速度之间增加了可控性.实验结果表明本算法大大减少了计算量,明显提高了运算速度,且具有很好的重建视频质量,适合于在低码率视频编码中应用.     

H.264 motion estimation algorithm based on video sequences activity

Motion estimation is an important part of H.264/AVC encoding progress, with high computational complexity. Therefore, it is quite necessary to find a fast motion estimation algorithm for real-time applications. The algorithm proposed in this letter adjudges the macroblocks activity degree first; then classifies different video sequences, and applies different search strategies according to the result. Experiments show that this method obtains almost the same video quality with the Full Search （FS） algorithm but with reduced more than 95% computation cost.     

一种搜索形状可变的快速运动估计算法

本文提出了一种以菱形和六边形联合搜索为基础的搜索形状可变(ＶＳＳ)的运动估计快速算法,何用于Ｈ．２６３、ＭＰＥＧ２、ＭＰＥＧ４中的视频编码。试验结果表明,在获得与现有ＴＳＳ、ＮＴＳＳ、４ＳＳ和ＤＳ等快速算法相当的图像质量和信噪比的情况下,该算法有效减少了搜索次数,提高了搜索效率,尤其对于中大运动量的视频图像运动估计效果更为明显。     

基于量子克隆选择的自适应多模式快速运动估计算法

该文提出一种新的基于量子克隆选择的自适应多模式快速运动估计算法。算法利用序列图像的时空预测运动矢量作为序列活动剧烈程度的依据,自适应选择搜索模式。静止块直接中止搜索;平缓运动类型块以(0,0)点为起始点,直接使用CDS搜索模式;剧烈运动类型块使用QCS/CDS联合搜索模式,首先使用量子克隆选择QCS寻找近似最优解,然后以近似最优解为起始点,使用CDS搜索。实验结果证明,算法在能够获得接近全搜索方法所得到的平均峰值信噪比前提下,平均搜索点数大大减少,搜索速度显著加快。     

A dynamic search pattern motion estimation algorithm using prioritized motion vectors

Motion estimation is one of the critical parts in video compression standards with a high computational load. Many motion estimation algorithms have been developed to reduce the number of search points compared to a full-search algorithm without losing the quality considerably. Most of them use fixed search patterns in their first step which may suffer from trapping into local minima or searching unnecessary blocks due to inappropriate size and type of search patterns. In this paper, a new dynamic search pattern using motion vectors of spatial and temporal neighboring blocks is proposed. The motion vectors of neighboring blocks are prioritized, in order to efficiently use of halfway stop technique. The simulation results indicate that proposed algorithm is very close to the full-search algorithm in quality, compared to other rivals. Moreover, the average number of searches is often less than other algorithms.     

基于亚像素运动矢量的AVS编码快速搜索算法

针对AVS视频编码系统中运动搜索模块运算量较大的问题,提出一种基于亚像素运动矢量的快速搜索算法.该算法利用整像素点进行分区域预测,并采用二步搜索法快速定位出最匹配亚像素点.实验结果表明,与传统方法相比,在峰值信噪比下降不足0.1 dB的情况下,该算法减少超过50%的亚像素搜索次数,视频编码时间缩短18%～30%.     

一种改进的运动估计快速搜索算法

运动估计是视频压缩中帧间预测编码的关键技术之一。在各个压缩标准中都广泛使用了基于块的运动估计技术。由于运动估计通常具有较大的运算量，因此对压缩性能具有重要的影响。文中分析了视频序列的特点和对现有的快速搜索算法深入理解的基础上提出了一种改进的快速运动估计搜索算法，实验表明该算法对压缩性能有较好的改进。     

A Multi-Pass True Motion Estimation Scheme With Motion Vector Propagation for Frame Rate Up-Conversion Applications

This paper presents a robust true motion estimation algorithm, designated as MPMVP (Multi-pass and Motion Vector Propagation), to enhance the accuracy of the motion vector fields in frame rate up-conversion applications. The MPMVP uses a multi-pass scheme to progressively refine approximate motion vectors to true motion vectors based upon the motion information acquired in previous passes. The multi-pass motion estimation process uses a large block size to detect the motion vectors within the objects themselves and small block sizes to detect the motion vectors along the object boundaries. Actually, the block size is progressively reduced during the search process. When the motion vector of a block is considered to be sufficiently accurate for motion estimation purposes, the block is said to be converged and the local motion vector search process terminates. A novel technique, referred to as motion vector propagation, is then applied to propagate the motion vector of the converged block to its neighboring blocks. This technique not only ensures that neighboring motion vectors within the same object have a high degree of spatial correlation, but also accelerates the convergence of the motion vectors in the neighboring blocks and therefore reduces the overall computational time and expense of the multi-pass motion vector search procedure. A novel distortion criterion is proposed to enhance the tolerance of the traditional sum-of-absolute-difference measurement technique applied in the motion estimation scheme to noise and shadow effects. The experimental results demonstrate that the proposed true motion estimation algorithm outperforms the traditional full search, 3DRS and TCSBP algorithms in terms of both the smoothness of the generated motion vector fields and the visual quality of the up-converted frames.     

Parabolic Motion-Vector Re-estimation Algorithm for Compressed Video Downscaling

For multimedia communications, there is a need to downscale a video prior to transmission because of the limitation of the bandwidth of a channel, and/or the different standards between transcoders. However, performing motion estimation in the downscaled video is computational intensive. In this paper, a parabolic motion vector re-estimation (PMVR) algorithm is proposed to predict motion vectors of the downscaled video. The proposed algorithm can significantly reduce computational complexity with slight PSNR degradation, in comparison with full search algorithm. Experimental results show that, with few additional computation, the proposed algorithm achieves a much higher quality than several existing algorithms.     

多搜索中心的运动估计快速算法

块大小可变的运动估计方法能提高视频编码性能,但也增加了计算时间.为了加快运动估计计算,本文提出了一种基于多搜索中心预测和搜索范围动态调整的快速算法.多搜索中心预测方法对当前宏块时间和空间上相邻块的运动向量进行分析,得出多个预测向量作为运动估计的搜索中心.相比传统预测方法,多搜索中心预测最高可提高约14.6%的预测精度....     

一种基于子搜索格雷码核的快速视频块运动估计算法

快速视频块运动估计是视频编码中的一个重要问题。在格雷码核( GCK)算法的基础上,提出一种改进的子搜索格雷码核( Sub-GCK)算法。理论上的计算复杂度分析表明：提出的子搜索格雷码核算法的运算量大约为原始格雷码核算法的22.1%。实验比较了子搜索格雷码核算法、原始格雷码核算法和其他几种常见的运动估计算法的编码性能,结果显示：新算法在保证编码质量的前提下,有效降低了运动估计时间,时间约为原始格雷码核算法的41.9%。     

Fast and efficient motion estimation using diamond zonal-based algorithms

Motion estimation has always been an important part of video encoding systems because it can reduce temporal redundancy effectively and thus has significant impact on the bit rate and the output visual quality of the encoded sequence. Unfortunately, when using the brute-force full search algorithm, motion estimation consumes a very large portion of the encoding time. Previously, several algorithms have been proposed which try to reduce complexity, usually, with a significant loss in visual quality. Based on the diamond zonal search framework we introduced recently, we propose in this paper a novel algorithm called advanced diamond zonal search (ADZS), which was submitted to and well received by the Moving Pictures Experts Group (MPEG) standard committee for possible inclusion as an encoder optimization tool. ADZS was criticized in MPEG for using fixed thresholds, which may not be suitable for all video sequences. To address this issue, we further propose a threshold-adaptive version called threshold-adaptive advanced diamond zonal search (TAADZS). Simulation results verify the superior performance of ADZS and TAADZS over other fast algorithms and the robustness of TAADZS over ADZS.This project has been supported by the Research Grants Council of the Hong Kong Special Administrative Region, China (project no. HKUST6057/99E) and the Hong Kong Telecom Institute of Information Technology. Parts of this paper have been previously published in conference proceedings.     

基于H.264视频编码的运动估计算法优化

 运动估计是视频压缩中最重要的环节.H.264编码器由于采用了高精度运动矢量,计算量迅速增长,运动估计消耗整个编码时间80％左右.本文在分析UMHexagonS算法的基础上,分别对UMHexagonS算法中搜索窗口大小的选择、大六边形搜索和小六边形(小钻石)搜索模式三方面做了优化,在保持了原有图象质量的情况下有效的节省了运动估计时间.通过对各种测试序列的实验证明,优化后的算法与UMHexagonS算法相比,在重建图象质量和码率接近的情况下,运动估计时间平均节省了18.292%,降低了算法的复杂度,提高了编码器的实时性.     

一种适用于AVS-M的自适应快速运动估计算法

为了减小移动视频编码标准(AVS-M)中运动估计模块的复杂度,提出了一种快速、有效的块匹配运动估计算法.该算法充分利用了视频图像中运动矢量场的中心偏置特性和时空相关性,根据运动类型自适应的选择搜索起点和搜索策略,结合改进的搜索模板和高效搜索中止准则,有效地降低了运动估计的运算量.实验结果表明,该算法在保证搜索精度的同时,大大减少了搜索点数.