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.     

A fast distance-based mode decision algorithm for 4×4 blocks in H.264/AVC intra prediction

H.264/AVC employs rate-distortion optimisation technique to achieve high coding efficiency, but it is computing-intensive. This letter presents a fast distance-based mode decision algorithm for 4×4 blocks in H.264/AVC intra prediction. Firstly, the distance between neighbouring blocks of the current block is defined. Then, the modes around up and left modes are selected as the candidate modes if the distance is small, otherwise early termination technique is used to further reduce the complexity, and either four or more modes are chosen based on the difference of rate-distortion optimisation cost. Experimental results show that our proposed algorithm can predict a 4×4 intra block by only about 3·52 modes and reduce the total encoding time by about 31·37% with negligible peak signal-to-noise ratio decrement and bit rate increment.     

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.     

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%.     

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.     

Optimal weighed Holoentropy for video compression: an advanced HEVC

ABSTRACT

In recent times, the applications of multimedia are rising in a greedy mode and hence the amount of video transactions is also increasing exponentially. This has shouted great demands on effective models on video encoding and also for reducing the transmission channel congestion. This research work introduces a managing technique termed weighted encoding for High-Efficiency Video Coding (HEVC). HEVC, also termed as MPEG-H Part 2 and H.265 is a video compression standard that is widely utilized AVC (H.264 or MPEG-4 Part 10). When compared to AVC, HEVC grants double the ratio of data compression at a similar level of quality of the video or considerably enhanced video quality at a similar bit rate. This work intends to optimize the weight that adopted in HEVC for encoding. For this, this paper proposes a new Iterative based propagation update in the water wave Optimization Algorithm (IPU-WWO), which is the improved form of Water wave Optimization (WWO). The performance of proposed IPU-WWO is compared over other conventional methods like Artificial Bee Colony (ABC), Firefly (FF), Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) with respect to Peak Signal to Noise Ratio (PSNR). By doing the encoding process, it minimizes the video size with perceptually better quality video or PSNR.     

Highly efficient CAVLC encoder for MPEG-4 AVC/H.264

In dealing with high-resolution video information, encoding (or decoding) with an efficient context-based adaptive variable length code (CAVLC) encoder is important. A highly efficient CAVLC encoder is proposed for video coding application of MPEG-4 AVC/H.264. The main concept is to use block-based pipelining to speed up encoding efficiency and reduce the pipeline storage elements by using the associated input buffer. We also use zero-block detection to speed up encoding efficiency and eliminate the same codeword from all the tables to save the hardware cost. Simulation results show that our design can meet the real-time processing for 1920 times 1088 resolution with lower operation frequency. We also accomplish the higher encoding throughput with a more complete CAVLC design than others. The proposed design has been implemented and synthesised with TSMC 0.18 mum standard cell library. The synthesis result indicates that the gate count is 12 125 with the clock constraint of 125 MHz.     

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.     

Efficient rate control scheme using modified inter-layer dependency for spatial scalability

Scalable video coding extension has been added to H.264AVC to support compression and encoding of multiple resolution video sequences, having different frame rates and fidelities in a single bit stream. The motion vectors and the residual data of the enhancement layers are derived from up-sampling the co-located macroblock (MB) of the base layer. The peak signal to noise ratio (PSNR) across the enhancement layers is degraded as up-sampling introduces distortion of high-frequency components. In this paper, a spatial-resolution-ratio-based MB mode decision scheme is proposed for spatially enhanced layers. The scheme uses the motion estimated at the base layer, to encode the respective MBs in the enhancement layers. The spatial–temporal search schemes at the enhancement layers are used to derive motion vectors and residues that are encoded using a quantization parameter obtained using independent rate control (IRC) scheme. The IRC from the prior art is modified to achieve better rate control per layer by recursive updates for mean absolute difference values of each basic unit. Proposed modified inter-layer dependency shows improvement in the PSNR for enhancement layers while the updated IRC enforces better IRC for all the layers.     

A no reference quality metric to measure the blocking artefacts for video sequences

The need to measure video quality arises in the development of video equipment and in the delivery and storage of video and image information. In this paper, we propose a new perceptually significant video quality metric to estimate the effect of block coding for standards H.264 AVC and MPEG2. Our method operates in the spatial domain and does not require a high complexity of computation. We evaluate the performance of the proposed method by using three sequences CIF ‘common intermediate file’ with different compression rate. We compare it with Suthaharan’s and MSU’s techniques by using ‘LIVE’ and ‘IVP’ databases. Results indicate that the proposed method outperforms Suthaharan’s and MSU techniques in H264 coder. They also indicate that our method is more effective than MSU’s and Suthaharan’s techniques for the H.264 AVC standards with the Spearman Rank Order Correlation Coefficient.     

H.264/AVC baseline profile to MPEG‐4 visual simple profile transcoding to reduce the spatial resolution

In this study, we propose a heterogeneous transcoding method of converting an H.264/Advanced video coding (AVC) Baseline profile (BP) video bitstream into an MPEG‐4 Visual simple profile (VSP) video bitstream. The proposed method reduces the spatial resolution for mobile terminals, which support only low resolution video bitstreams. When the H.264/AVC BP video bitstream is transformed into the MPEG‐4 VSP video bitstream, the conversions between the H.264/AVC BP block types and the MPEG‐4 VSP block types are performed by analyzing the macroblocks (MBs) conversion probability and calculating the difference values of motion vector. The proposed transcoding method runs on average 5.5 times faster than the cascaded transcoding methods, for a degradation of the PSNR (peak‐signal‐to ratio) of less than 0.5 dB. © 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 24–33, 2006     

自适应六边形-菱形运动估计算法及其在H.264中应用

运动估计是视频图像编码中运算量很大的部分,也是影响系统实时性能的瓶颈。为了减少图像编码的运算量,文章介绍和分析了用于视频编码标准H.264的基于六边形的搜索算法(HS),在此基础上根据H.264多模式的运动估计提出自适应六边形-菱形整像素算法,它体现了粗定位和准确定位的并行处理思想,仿真结果表明在获得与HS快速算法相当的图像质量和信噪比的情况下,可提高H.264视频编码的速度和效率。     

Objective analysis and bit rate analysis of HEVC compressed 4D-fMRI images

Medical imaging and clinical diagnostics are complementary to one another since their analysis is typical and contains critical information. The growing volume of data has become one of the biggest challenges, as the acquisition of medical modalities is currently having high resolution from the improved and efficient machines (3 to 7 T or more). Moreover, image and video compression is a need with the consideration that there should not be any gap for losing the important information. Less bitrate requirement with high compression ratio without sacrificing important detail is a challenge these days. The current study, is dealing with the compression of 4D-functional medical resonance images (fMRI) with a codec, that is, high-efficient video coding (HEVC/H.265) and its objective analysis along with its predecessor that is advanced video coding (AVC/H.264) and with VP8 (WebM Project of Google) reported here. Further, the bit rate analysis that has been conducted, also accounts in conjunction with the bitrate investigation, which is an imperative perspective vital for the telemedicine field. The simulation results reported here represents the compression ratio (CR = 118.23:1) with HEVC/H.265 codec over the compression ratio (CR = 20.52:1) provided by AVC/H.264 and VP8 (CR = 78.29:1). There has been significant improvement observed in alignment of the peak signal-to-noise ratio (APSNR), structural similarity (SSIM), and mean squared error (MSE) metrics. Overall, the performance of the anticipated technique is satisfactory for the forthcoming telemedicine or clinical use.     

Optical flow-based motion compensation algorithm for very low-bit-rate video coding

In this article, we propose an efficient compression algorithm for very low-bit-rate video applications. The algorithm is based on (a) an optical-flow motion estimation to achieve more accurate motion prediction fields; (b) discrete cosine transformation (DCT) coding of the motion vectors from the optical-flow estimation to reduce the motion overheads; and (c) an adaptive threshold technique to match optical flow motion prediction and minimize the residual errors. Unlike the classic block-matching based DCT video coding schemes in MPEG-1/2 and H.261/3, the proposed algorithm uses optical flow for motion compensation and the DCT is applied to the optical flow field instead of predictive errors. Thresholding techniques are used to treat different regions to complement optical flow technique and to efficiently code residual data. While maintaining a comparable peak signal-to-noise ratio (PSNR) and computational complexity with that of ITU-T H.263/TMN5, the reconstructed video frames of the proposed coder are free of annoying blocking artifacts, and hence visually much more pleasant. The computer simulation are conducted to show the feasibility and effectiveness of the algorithm. Results at 11 kbps are presented which can be used for videophone applications in the existing public switched telephone network (PSTN). © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 230–237, 1998     

Novel fast block motion estimation using diamond‐arc‐hexagon search patterns

Abstract

This work presents a novel block motion estimation (ME) approach, diamond‐arc‐hexagon search (DAHS), which uses diamond, arc, and hexagon search patterns to accomplish the fast searching process. According to the characteristic of the center‐based motion vector distribution for the real‐world video sequence, DAHS employs a small diamond pattern extended hexagon search to refine the central area search. Furthermore for estimation in large motion situations, the strategy of the large diamond‐to‐arc search can preserve good performance. Experimental results indicate that DAHS is suitable for both (quasi‐) stationary and large motion searches. DAHS outperforms the efficient three‐step (E3SS) and hexagon‐based search (HEXBS) in prediction quality, and improves the searching speed about 9% compared to E3SS. The proposed algorithm was tested using several sequences and delivered excellent performance in search speed and prediction of video quality. The DAHS can be applied to real‐time video processes, such as H.264/MPEG‐4 advanced video coding (AVC) and scalable video coding (SVC).     

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.     

A HEVC Video Steganalysis Algorithm Based on PU Partition Modes

Steganalysis is a technique used for detecting the existence of secret information embedded into cover media such as images and videos. Currently, with the higher speed of the Internet, videos have become a kind of main methods for transferring information. The latest video coding standard High Efficiency Video Coding (HEVC) shows better coding performance compared with the H.264/AVC standard published in the previous time. Therefore, since the HEVC was published, HEVC videos have been widely used as carriers of hidden information.
In this paper, a steganalysis algorithm is proposed to detect the latest HEVC video steganography method which is based on the modification of Prediction Units (PU) partition modes. To detect the embedded data, All the PU partition modes are extracted from P pictures, and the probability of each PU partition mode in cover videos and stego videos is adopted as the classification feature. Furthermore, feature optimization is applied, that the 25-dimensional steganalysis feature has been reduced to the 3-dimensional feature. Then the Support Vector Machine (SVM) is used to identify stego videos. It is demonstrated in experimental results that the proposed steganalysis algorithm can effectively detect the stego videos, and much higher classification accuracy has been achieved compared with state-of-the-art work.     

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.26L关键编码技术性能研究

H．26L的编码效率比已有的其他视频编码标准有很大的提高。在相同PSNR下与H．263和MPEG4相比，H．26L在低码率时的输出码率平均节省分别约为40％和36％，在高码率时的输出码率平均节省分别约为55％和45％。本文描述了H．26L的编码器结构框图，对各模块的作用和使用的技术进行了综述，并与其他视频标准中的主要技术进行了比较。对H．26L中几种技术在高、中和低码率下对编码效率的影响进行了实验研究并给出实验结果，这对于不同码率的视频应用时编码器的参数选择和模式选择有重要意义。     

Ray-space数据片内和片间相关性压缩分析

Ray-space数据特征分析表明,其片内和片间均存在很大相关性,并且其数据有明显的方向性特征。通过最优宏块分割、不同精度的块匹配和多参考片预测结果分析,讨论了适合Ray-space数据特点的片内和片间预测技术。与传统的只利用片内相关性的压缩技术相比,利用上述两类相关性,并结合Ray-space数据方向性特征,能进一步提高编码压缩效率。在获得相同重建图像质量下,可使基于H.264的Ray-space压缩方法比基于H.263的方法在码率上节省50%,比JPEG的方法节省75%左右。