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.     

一种新的面向隔行视频的AVS帧内预测模式

详细介绍了AVS1-P2中的帧内预测和MBAFF技术,提出了一种新的帧内预测模式.通过分析其中的5种亮度帧内预测模式和新帧内预测模式的相关性利用度,证明该模式很好地利用了隔行视频像素的空间分布特点,与原有的预测模式相比,更好地去除了图像块之间的空间相关性.实验表明该模式可以在标清、高清隔行视频的帧内预测上获得平均0.12dB以上的信噪比增益,平均减少1.77%的码流,是一种有效提高编码效率的预测模式.     

Intra mode decision and frame layer Lagrange multiplier adjustment scheme for H.264 based on structural similarity

H.264 takes rate distortion optimisation (RDO) technique to perform intra and inter mode decision and achieves higher coding efficiency, but the objective distortion metric such as mean square error (MSE) is employed in traditional RDO framework, which cannot acquire optimal subjective quality. In this paper, structural similarity (SSIM)-based subjective distortion is applied to RDO-based intra mode decision in H.264 I frame video coding, and a linear SSIM distortion model is firstly proposed and SSIM-based rate distortion cost function for intra mode decision is defined. Furthermore, a content adaptive frame layer Lagrange multiplier adjustment scheme is proposed to balance the tradeoff between rate and SSIM distortion better. Experimental results show that, the proposed method encodes image structural information more effectively and thus acquires better perceptual quality and subjective RDO performance compared with objective distortion-based RDO method. Under the same perceptual quality, our scheme achieves about 8·03% I frame bit rate reduction on average for various sequences over MSE-based RDO employed in JM reference software.     

基于编码模式的H.264/AVC视频信息隐藏算法

本文提出一种基于编码模式的H.264/AVC信息隐藏方法,通过调制某些宏块的编码模式,分别在Ⅰ帧、P帧和B帧中嵌入隐秘信息.对帧内4x4预测模式的宏块,是通过调整宏块中某个4×4块的编码模式嵌入隐秘信息;对P帧和B帧其它类型的宏块,则是通过调整宏块的编码模式嵌入隐秘信息,模式调整后对宏块做了优化处理.在模式调制过程中引入率失真代价,取得了较好的率失真平衡,减小了隐秘信息嵌入后对视频质量和视频码流的影响.该算法可以实现隐秘信息的快速提取,满足视频实时处理的要求,实验仿真结果证明了该算法的有效性.     

一种基于差错估计的H.264视频容错算法

针对最新的视频编码标准H．264,设计了一种基于差错估计的容错算法。该算法结合信道条件,估计差错在视频编码帧之间的扩散;根据每个宏块差错的程度,自适应地判断是否对该宏块进行帧内编码,从而抑制差错的积累。在存在反向信道的环境中,该算法可以利用解码器反馈的实际宏块错误信息,跟踪差错扩散,对其进行更准确的估计,以提高容错性能。仿真表明,在各种信道条件下,该算法相对于随机帧内宏块更新算法．重建图像平均峰值信噪比有1．3～2．5dB的提高。同时,该算法对信道估计的要求不高,运算量和存储量的增加较低,具有实用性。     

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     

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...     

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.     

Reversible Data Hiding Based on Run-Level Coding in H.264/AVC Video Streams

This paper presents a reversible data hiding (RDH) method, which is designed by combining histogram modification (HM) with run-level coding in H.264/advanced video coding (AVC). In this scheme, the run-level is changed for embedding data into H.264/AVC video sequences. In order to guarantee the reversibility of the proposed scheme, the last nonzero quantized discrete cosine transform (DCT) coefficients in embeddable 4×4 blocks are shifted by the technology of histogram modification. The proposed scheme is realized after quantization and before entropy coding of H.264/AVC compression standard. Therefore, the embedded information can be correctly extracted at the decoding side. Peak-signal-noise-to-ratio (PSNR) and Structure similarity index (SSIM), embedding payload and bit-rate variation are exploited to measure the performance of the proposed scheme. Experimental results have shown that the proposed scheme leads to less SSIM variation and bit-rate increase.     

Optimal Mode Decision Method for Interframe Prediction in H.264/AVC

Studies show that encoding technologies in H.264/AVC, including prediction and conversion, are essential technologies. However, these technologies are more complicated than the MPEG-4, which is a standard method and widely adopted worldwide. Therefore, the amount of calculation in H.264/AVC is significantly up-regulated compared to that of the MPEG-4. In the present study, it is intended to simplify the computationalexpenses in the international standard compression coding system H.264/AVC for moving images. Inter prediction refers to the most feasible compression technology, taking up to 60% of the entire encoding. In this regard, prediction error and motion vector information are proposed to simplify the computation of inter predictive coding technology. In the initial frame, motion compensation is performed in all target modes and then basic information is collected and analyzed. After the initial frame, motion compensation is performed only in the middle 8×8 modes, and the basic information amount shifts. In order to evaluate the effectiveness of the proposed method and assess the motion image compression coding, four types of motion images, defined by the international telecommunication union (ITU), are employed. Based on the obtained results, it is concluded that the developed method is capable of simplifying the calculation, while it is slightly affected by the inferior image quality and the amount of information.     

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%。     

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.     

A MV-Based Steganographic Algorithm for H.264/AVC without Distortion

H.264/AVC video is one of the most popular multimedia and has been widely used as the carriers of video steganography. In this paper, a novel motion vector (MV) based steganographic algorithm is proposed for the H.264/AVC compressed video without distortion. Four modules are introduced to eliminate the distortion caused by the modifications of motion vectors and guarantee the security of the algorithm. In the embedding block, the motion vector space encoding is used to embed a (2n+1)-ary notational number into an n-dimension vector composed of motion vectors generated from the selection block. Scrambling is adopted to disturb the order of steganographic carriers to improve the randomness of the carrier before the operation of embedding. The re-motion compensation (re-MC) block will re-construct the macroblock (MB) whose motion vectors have been modified by embedding block. System block plays the role of the generator for chaotic sequences and encryptor for secret data. Experimental results demonstrate that our proposed algorithm can achieve high embedding capacity without stego video visual quality distortion, it also presents good undetectability for existing MV-based steganalysis feature. Performance comparisons with other existing algorithms are provided to demonstrate the superiority of the proposed algorithm.     

A Cauchy distribution-based ternary hypothesis testing for bipolar additive watermark detection in H.264/AVC video

Abstract

The statistical distribution of discrete cosine transform (DCT) coefficients is important for video watermarking since they are the main carriers for watermark embedding. For the statistical distribution of intra-coded DCT coefficients in the H.264/AVC video stream, non-parametric hypothesis test is utilised to verify that Cauchy distribution is better than generalised Gaussian distribution (GGD). Moreover, ternary hypothesis test is introduced into the detection of bipolar additive watermarks. By adjusting the watermark strength parameter, the detector performance can be guaranteed. Experimental results show that for those bipolar additive watermarks in the H.264/AVC stream, the proposed approach can achieve a detection accuracy of more than 80% on average.     

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.     

H.264帧内预测与帧间块模式选择快速算法

针对H.264帧间预测时的多子块模式选择和帧内预测的多模式选择问题,提出了一种实用的基于统计门限的模式快速选择算法,通过门限设定有效限定了编码模式的选择范围.多组视频序列的实验结果表明,基于统计门限的帧内预测模式选择算法在Ⅰ帧的PSNR值有微小变化的情况下,大大降低了编码时间,Ⅰ帧的编码时间降低17%～23%,PSNR下降不到0.4%.基于统计门限的帧间块模式选择算法使得平均PSNR值下降了0.047dB(PSNR最大下降不到1%),但是相对全模式预测时,编码器速度提高了20%～30%.     

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。     

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。     

Improved upsampling filter design for spatially scalable video coding

Scalable video coding is an ongoing standard, and the current working draft (WD) is to be finalized as an extension of H.264/AVC. It provides scalability at the bit stream level with good compression efficiency and allowing free combinations of spatial, temporal and quality scalability. In the WD, a uniform up‐sampling filter is employed to interpolate the base layer frames. This technique achieves high interpolated precision for both luma component and chroma components, but it results in extremely large encoding time which obstructs it from practical use. This paper proposes an improved up‐sampling filter design for spatially scalable video coding. It makes use of a basic characteristic of human vision system and intends to assign different filters for different components. Specifically, current usage of the 6‐tap up‐sampling filter is only for luma component, but for chroma components, much more simplified filter such as 4‐tap filter or 2‐tap filter should be used instead. Experimental results show that improved up‐sampling filter design reduces the computational complexity significantly with negligible coding loss and bit‐rate increases. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 315–319, 2007