基于X264的运动估计算法研究

H.264是目前最新的视频编解码标准,研究运动估计基本原理和研究状况的基础上,对X264编码器的三种运动估计算法进行分析和比较,实验结果表明可以在保证例像质量的情况下,提高编码速度,有效压缩视频.     

H.264编码标准的分析研究

主要学习研究H.264标准中的关键技术,H.264标准是最新的视频编码标准,它采用一系列先进的编码技术,在编码效率、抗误码能力、网络适应性等方面表现出超越以往各标准的优势,H.264的研究和应用将大大推进视频技术的发展.     

基于H.264的一种视频编码算法的研究与FPGA实现

H.264是由ITU-T视频编码专家组VCEG和ISO/IEC运动图像专家组MPEG联合制订的新一代视频编码标准。而运动估计是整个编码过程中最耗时的一部分,它的效率直接决定了整个编码系统的效率。因此本文在混合非对称十字多六边形搜索算法原理的基础上,提出了一种混合六边形搜索算法,使四种标准算法合理搭配。并且在FPGA上设计了一种有效的硬件结构实现该算法。     

一种快速实现H.264运动估计的方法

本文提出一种快速实现H.264运动估计的算法。该算法利用视频图像中存在大量空/时域冗余这一特点,在运动估计过程中引入预判空间相关性和时域稳定性的方法,节省了大量不必要的计算步骤。试验结果表明,该算法运动估计时间仅为JM84的30.3%,峰值信噪比(PSNR)仅降低1.1%,码率平均增加3.95%。     

视频编码标准H．264的技术革新及应用

本文阐述了H．264的概念,分析了H．264的技术进步,介绍了H．264的广泛应用及在应用中的良好表现。     

基于H.264的改进运动估计算法及其性能对比实验研究

为提高视频压缩效率,在传统搜索算法的基础上,结合实际运动图像中的运动向量,以水平方向向量为主要特点,提出一种利用偏水平十字模板搜索与偏向双菱形模板搜索相结合的改进搜索算法。该改进算法可以根据运动向量的特点来减少模板的搜索点数,达到提高视频压缩效率、节省运动估计时间的目的。性能对比实验结果表明:该改进算法适合各种运动类型的视频序列,尤其适用于运动变化剧烈的序列,并且能够在PSNR值和码率值极其接近FS算法的情况下,对QCIF格式图像的运动估计时间(MET)减少约95%,对CIF格式图像的运动估计时间(MET)减小约94.5%,大大减少运动估计时间。     

基于H.264的自适应可伸缩编码研究

为了更好地适应网络及终端的多样性,本文针对基于H.264的可伸缩编码,提出了一种基于运动区域的自适应可伸缩编码的优化方案.该方案根据基本层的运动信息及编码模式自动提取图像的运动感兴趣区域,并以独立片的形式对其进行时间,空间和质量上的可伸缩编码,实现选择性增强.实验结果表明,该方案不仅能大幅降低编码复杂度,而且使增强层码流集中包含运动区域信息,从而提高运动区域的重建质量及整幅图像的主观质量.     

一种基于预测模式的H.264/AVC视频信息隐藏改进算法

提出了一种基于帧内预测模式调制的H.264/AVC视频信息改进隐藏算法.选择参考像素亮度值接近的帧内4×4块,通过对预测模式值进行调制以实现隐秘信息的嵌入,而预测模式调制过程是将最优预测模式变为满足嵌入条件的具有率失真开销最小的预测模式,以尽量减小预测模式的改变对视频客观质量的影响.信息的提取过程不需要原始载体视频,也...     

基于H.264的视频监控系统设计

研制一种基于H.264网络视频监控系统,采用OMAP5910芯片作为嵌入式CPU芯片,片内集成了H.264硬件编解码视频处理单元。从系统的硬件设计和软件设计两部分介绍系统的音视频采集、压缩、存储、及系统控制等方面设计。     

H.264/AVC编码器算法优化分析

H.264/AVC是JVT(联合视频组)和MPEG(活动图像编码专家组)联合提出的具有更高压缩效率的视频编码标准,主要分析本编码器主要采用的快速算法有:帧内模式快速选择算法、帧间模式快速选择算法、快速运动搜索算法等内容,对于进一步深化设计H.264/AVC编码器具有一定帮助。     

Fast intra prediction mode decision for H.264/AVC video coding

Abstract

Intra coding is used for reducing the spatial redundancy in video coding. H.264 supports several macroblocks of predictions for intra coding such as luma block four 16×16 modes, nine 4×4 modes and chroma block four modes, which significantly improve intra coding efficiency, but increase the encoding complexity. In order to select the best mode, we need to calculate the cost of the various modes. In this paper, a fast intra prediction mode decision for H.264/AVC video coding is proposed. Based on Laplacian, this intra prediction mode decision detects edges and selects the best mode for the block. This mode decision can shorten the time to reduce the encoding time. The experimental results show that the proposed algorithm achieves an encoding time saving of 70% on average.     

Intra mode selection in downsizing video transcoder based on H.264

An intra mode selection scheme is proposed in this work, which supports both downsizing transcoding and re‐quantization transcoding simultaneously. In the proposal, a total number of nonzero coefficients in precoded frame is used as criterion and a thresholding method is applied to select intra macroblock mode in re‐encoder. To calculate this threshold, which is related to re‐quantization parameter (denoted as Q_r), we propose a Th_I‐Q_r model which includes direct method and percentage I16MB method. In the former, an exponent model is proposed to describe relationship between the threshold and the Q_r; while in the latter, the threshold Th_I is converted into percentage of macroblocks with I16MB mode in the downsized frame (denoted as per_16), and relationship between the per_16 and the Q_r is also modeled as an exponent function. Then the two exponent models are all converted into linear regression model, and least square estimation is used to estimate the parameters of the models. Furthermore, if I4MB mode is selected for one macroblock, the intra prediction modes in precoded frame are utilized to select prediction mode for every 4 × 4 block of the macroblock in downsized frame to reduce computational complexity. We compared rate distortion performance and computational complexity of the proposed method with rate‐distortion optimization method. Simulation results demonstrate that on the precondition of compression performance of the proposal being close to the results of the rate‐distortion optimization method, the proposed method can save up to 30 and 80% in total encoding time and mode decision time, respectively. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 340–349, 2009     

AVC/H.264标准中高效运动估计硬件结构设计

为解决视频编码标准AVC/H.264中运动估计高计算复杂度问题,提出了一个高效运动估计硬件实现结构.该结构能够实现多尺寸块运动估计处理,并且具有高流水效率和高性价比的特点.结构灵活性强,通过改变PE单元和加法树的流水级数能够达到面积和计算能力的折中.实验表明,该结构在搜索窗为65×65时,针对图像尺寸为720×576的视频,每秒最高可以编码48幅图像.     

基于受损区域运动特征的时域错误隐藏算法

为解决视频压缩数据在网络传输中的误码或丢包问题,提出了一种适用于数字视频编码标准H.264的时域错误隐藏算法。该算法结合H.264中多尺寸编码块模式的特点,通过对受损块邻域块的模式分析来判定受损块模式,并针对各子块的运动类型分别建立相应的运动矢量候选集,从而选择最优运动矢量重建受损块。实验结果表明,该算法有效增强了对复杂运动区域重建的适应性,在不同的网络丢包率环境下均可实现较好的主观和客观重建图像质量。     

Fast mode decision based on systematic deployment of predictive resources for H.264/AVC

Abstract

This paper presents a well organised fast mode decision scheme for H.264/AVC that systematically integrates and deploys applicable predictive resources using constructive compromise. This scheme is constructed by primary SKIP mode checking, spatial prior temporal hard decision (STHD), and succinct mode decision (SMD). The STHD is connected with the predictive macroblocks searched. In STHD, only when spatial hard decision fails, temporal hard decision is performed using the potential partition characteristic vector (PPCV) addressed. If it fails, too, then SMD takes care of mode checking also using PPCV. The SMD consists of succinct P16?×?16 mode decision and succinct geometric/statistical extension examination, which are formed as an effective two-stage judgment. Extensive experimental results demonstrate that the proposed method by systematically deploying the predictive resources can achieve 58–74% runtime savings in encoding QCIF, CIF and high definition videos with low performance losses. In addition, most processes of the proposed scheme could be implemented on logical operations, only.     

H.264帧间预测模式选择算法研究与优化

H.264出色的压缩性能是以计算复杂度的提高为代价的。使用快速帧间预测模式选择算法是提高H.264编码速率的一种有效方法。文中对H.264帧间预测模式选择的复杂度进行分析之后，对基于X264参考程序的帧间预测算法提出改进，测试结果显示这种改进能将H．264的编码速率提高55％左右。     

Efficient bit‐plane coding scheme for fine granular scalable video coding

In this paper, we propose a new efficient bit‐plane coding method for fine granular scalable (FGS) video coding. The general structure of the proposed bit‐plane coding method is based on the traditional bit‐plane coding scheme in MPEG‐4 FGS. However, to enhance coding efficiency of bit‐plane encoding, we apply an efficient probability estimation scheme through employing the binary arithmetic coding. For probability estimation, various context models are designed to take advantage of the characteristics of each bit‐plane as well as the correlations of symbols among different bit‐planes. Experimental results show that the proposed FGS coding scheme provides better coding performance, compared to the well‐known FGS coding schemes in MPEG‐4 FGS and JSVM. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 113–120, 2006.