An improved scheme for data hiding in encrypted H.264/AVC videos

Recently, a novel scheme to hide data into encrypted H.264/AVC videos using code-word substitution has been proposed by Xu et al. However, the statistical analysis of CAVLC code-words demonstrate that Xu et al.’s work does not fully exploit redundancy existing in CAVLC code-word for data embedding. In this paper, an improved version of Xu et al.’s data hiding method in encrypted H.264/AVC videos is proposed. Specifically, when suffixLength is equal to 1, data embedding is performed by paired code-word substitution. When suffixLength is greater than 2, not the single code-word substitution but the multiple-based notational system is adopted for data embedding. Experimental results have demonstrated that the improved method is indeed capable of providing a larger embedding capacity in comparison with Xu et al.’s method. Moreover, both encryption and data embedding can be accomplished without affecting the coding efficiency of H.264/AVC by keeping exactly the same bitrate.     

Efficient information hiding in H.264/AVC video coding

This paper proposes a new real-time information hiding algorithm on latest H.264/AVC video coding standard. The information is embedded into the Trailing Ones of 4×4 blocks during the Context-based Adaptive Variable Length Coding (CAVLC) process. This algorithm is efficient with low computational complexity. The simulation results show that the degradation of video quality is negligible, and the same overall bit-stream length is maintained. Based on this information hiding method, a video subtitle transmission scheme is proposed. Under the simulation of different RTP packet loss channels, the embedded information can be well recovered. The comparison with other algorithms shows the superiority of our proposed method.     

Mode dependent loop filter for intra prediction coding in H.264/AVC

In this paper, a high performance and low complexity loop filter is proposed for intra prediction coding. Although the deblocking loop filter (DLF) has achieved outstanding performance on suppressing quantization noise, it also induces details information loss because of the smoothing operation. To achieve better restoration performance, we propose a filter set named mode dependent loop filter (MDLF) which adaptively select the filter coefficients according to various local characteristics. In the homogeneous areas, the task of the filter emphasizes on smoothing the noise. In the heterogeneous areas, the proposed filter concentrates on preserving the details. Based on the spatial correlation assumption and statistical analysis, the intra mode combination is used to classify the training samples with different local characteristics. Then the classical least mean square error framework is employed to solve the coefficients for the proposed filter set. In this way, a more efficient adaptive loop filter scheme can be achieved for specific intra mode combination. Experiment results show that the proposed loop filter achieves superior coding gains compared to the H.264/AVC High Profile. Furthermore, relative to QALF+DLF, a comparable performance also can be achieved by the proposed MDLF with far less complexity increase.     

基于H.264/AVC的视频信息隐藏算法

在H.264/AVC的帧内预测环节,调制H.264/AVC编码中I帧4×4亮度块的帧内预测模式实现信息隐藏.这种调制基于该模式与待隐藏比特之间的映射规则进行.宿主4×4块的具体位置由各块自身特点结合密钥所指定的嵌入位置模板确定.信息的提取过程不需要原始视频内容,也不需完全解码,而只要对码流中的帧内预测模式进行解码即可.     

General Architecture for MPEG-2/H.263/H.264/AVC to H.264/AVC Intra Frame Transcoding

The latest international video-coding standard H.264/AVC significantly achieves better coding performance compared to prior video coding standards such as MPEG-2 and H.263, which have been widely used in today’s digital video applications. To provide the interoperability between different coding standards, this paper proposes an efficient architecture for MPEG-2/H.263/H.264/AVC to H.264/AVC intra frame transcoding, using the original information such as discrete cosine transform (DCT) coefficients and coded mode type. Low-frequency components of DCT coefficients and a novel rate distortion cost function are used to select a set of candidate modes for rate distortion optimization (RDO) decision. For H.263 and H.264/AVC, a mode refinement scheme is utilized to eliminate unlikely modes before RDO mode decision, based on coded mode information. The experimental results, conducted on JM12.2 with fast C8MB mode decision, reveal that average 58%, 59% and 60% of computation (re-encoding) time can be saved for MPEG-2, H.263, H.264/AVC to H.264/AVC intra frame transcodings respectively, while preserving good coding performance when compared with complex cascaded pixel domain transcoding (CCPDT); or average 88% (a speed up factor of 8) when compared with CCPDT without considering fast C8MB. The proposed algorithm for H.264/AVC homogeneous transcoding is also compared to the simple cascaded pixel domain transcoding (with original mode reuse). The results of this comparison indicate that the proposed algorithm significantly outperforms the mode reuse algorithm in coding performance, with only slightly higher computation.     

Hardware design of motion data decoding process for H.264/AVC

In H.264/AVC, motion data can be basically derived by the following two schemes: one is a typical spatial prediction scheme based on the DPCM and the other is a sophisticated spatiotemporal prediction scheme for the skipped motion data, formally referred to as a direct mode. We verified through instruction level profiling that when these schemes are combined with various H.264/AVC coding techniques, the computational burden to derive the motion data could be considerably aggravated. Specifically, its computational complexity amounts to maximally 55% of that of the overall syntax parsing process. In this paper, we aim at an efficient hardware design of the motion data decoding process for H.264/AVC, for which all the key design considerations are addressed in detail and respective rational answers are presented. As comparing the resulting hardware design with the processor-based solution, its effectiveness was clearly demonstrated. The proposed design was implemented with 43.2 K logic gates and three on-chip memories of 3584 bits using Samsung Semiconductor’s Standard Cell Library in 65 nm L6LP process technology (SS65LP), and was capable of operating the H.264/AVC high-profile video bitstream of 1080p@60fps at 100 MHz consuming 843 μW.     

基于多分类的QDCT域大容量H.264/AVC视频信息隐藏算法

提出了一种在开环外的量化离散余弦变换(QDCT )系数上的H.264视频信息隐藏算法。在抑制漂移失真的条件下,对 邻块所需参考像素进行多组分类。其次,充分挖掘帧 内4×4亮度可用QDCT系数对,结合9进制方向调整(EMD)嵌入算法和 矩阵编码,实 现秘密信息的高容量嵌入。同时,通过最多修改一组QDCT系数保证了含密视频的质量。 此外,本文的信息提取算法不需要对含密视频完全解码,只需得到QDCT系数和帧内预测 模式,即可完全提取秘密信息。实验结果表明,本文算法在大幅度提高嵌入容量的同时,对 比特率和视频的质量影响不大。     

H.264/AVC video for wireless transmission

H.264/AVC will be an essential component in emerging wireless video applications thanks to its excellent compression efficiency and network-friendly design. However, a video coding standard itself is only one component within the application and transmission environment. Its effectiveness strongly depends on the selection of appropriate modes and parameters at the encoder, at the decoder, as well as in the network. In this paper we introduce the features of the H.264/AVC coding standard that make it suitable for wireless video applications, including features for error resilience, bit rate adaptation, integration into packet networks, interoperability, and buffering considerations. Modern wireless networks provide many different means to adapt quality of service, such as forward error correction methods on different layers and end-to-end or link layer retransmission protocols. The applicability of all these encoding and network features depends on application constraints, such as the maximum tolerable delay, the possibility of online encoding, and the availability of feedback and cross-layer information. We discuss the use of different coding and transport related features for different applications, namely video telephony, video conferencing, video streaming, download-and-play, and video broadcasting. Guidelines for the selection of appropriate video coding tools, video encoder and decoder settings, as well as transport and network parameters are provided and justified. References to relevant research publications and standardization contributions are given.     

Transparent encryption techniques for H.264/AVC and H.264/SVC compressed video

Transparent encryption of video content requires to provide a video preview that is left in plaintext, while the enhancement information is encrypted. In this paper we propose three algorithms that provide transparent encryption. The first two ones are based on the idea of generating controlled drift in such a way as to obtain the desired quality level, while the third algorithm employs scalable video coding. We provide experimental results on several video sequences, as well as a security analysis, showing that the proposed algorithms provide an effective framework to perform transparent encryption.     

视频编码H.264/AVC新技术及其优化

本文详细介绍了视频编码新标准H.264/AVC中的运动估计和运动补偿、预测、证书变换、量化、熵编码环路滤波、帧切换等技术及其优化设计.     

H.264/AVC视频编码标准的技术特点及应用分析

H.264／AVC是ITU-T视频编码专家组和ISO／IEC运动图像专家组(MPEG)共同开发出来的最新视频编码标准,它具备许多新的技术特点,如:多模式运动预测、柔性宏块排序、整数变换、一致性变字长编码、内容自适应二进制算术编码、分层编码、错误约束机制、错误掩盖技术及高效的比特流切换技术等等。本文在阐述该标准系统层结构的基础上,分析其主要技术特点及H.264／AVC VBR码流特性,阐述该标准在IP网络及无线网络中的应用情况。     

ASIP Approach for Implementation of H.264/AVC

This paper presents an Application Specific Instruction Set Processor (ASIP) for implementation of H.264/AVC, called Video Specific Instruction-set Processor (VSIP). The proposed VSIP has novel instructions and optimized hardware architectures for specific applications, such as intra prediction, in-loop deblocking filter, integer transform, etc. Moreover, VSIP has coprocessors for computation intensive parts in video signal processing, such as inter prediction and entropy coding. The proposed VSIP has much smaller area and can dramatically reduce the number of memory access compared with commercial DSP chips, which result in low power consumption. Moreover, the proposed hardware accelerators have small size, consume low power consumption, and thus, they can support real-time video processing. VSIP has been thoroughly verified using an FPGA board having the Xilinx™ Virtex II. VSIP can implement a real-time H.264/AVC decoder. The proposed VSIP is one of promising solutions for video signal processing.

H.264熵解码器CAVLC的硬件设计

H.264/AVC是ITU-T和MPEG组织共同推出的最新一代视频压缩标准,其压缩效率较H.263和MPEG-4 simple profile有显著提高.     

Requantization transcoding for H.264/AVC video coding

In this paper, efficient solutions for requantization transcoding in H.264/AVC are presented. By requantizing residual coefficients in the bitstream, different error components can appear in the transcoded video stream. Firstly, a requantization error is present due to successive quantization in encoder and transcoder. In addition to the requantization error, the loss of information caused by coarser quantization will propagate due to dependencies in the bitstream. Because of the use of intra prediction and motion-compensated prediction in H.264/AVC, both spatial and temporal drift propagation arise in transcoded H.264/AVC video streams. The spatial drift in intra-predicted blocks results from mismatches in the surrounding prediction pixels as a consequence of requantization. In this paper, both spatial and temporal drift components are analyzed. As is shown, spatial drift has a determining impact on the visual quality of transcoded video streams in H.264/AVC. In particular, this type of drift results in serious distortion and disturbing artifacts in the transcoded video stream. In order to avoid the spatially propagating distortion, we introduce transcoding architectures based on spatial compensation techniques. By combining the individual temporal and spatial compensation approaches and applying different techniques based on the picture and/or macroblock type, overall architectures are obtained that provide a trade-off between computational complexity and rate-distortion performance. The complexity of the presented architectures is significantly reduced when compared to cascaded decoder–encoder solutions, which are typically used for H.264/AVC transcoding. The reduction in complexity is particularly large for the solution which uses spatial compensation only. When compared to traditional solutions without spatial compensation, both visual and objective quality results are highly improved.     

基于兴趣区域的H.264/AVC会话视频传输算法

针对会话视频的严格的实时性要求,提出一种基于H.264/AVC会话视频的错误抵抗编方法;建立一种低复杂度的感兴趣区域分割算法;基于所提分割算法,对感兴趣区域进行长期参考帧预测编码,从而达到提高感兴趣区域的视频传输质量的目标.所提方法具有低复杂度的特点,能够满足会话视频的实时性要求,并且易于移植入H.264/AVC编码器.仿真结果证明了算法的鲁棒性和编码有效性.     

H.264/AVC中并行通用变换结构设计

提出了一种用于H.264/AVC编解码器的通用并行变换结构,并利用Verilog语言进行了电路设计.该并行结构主要包含4个移位器和16个累加器,可以完成H.264/AVC中的全部4×4变换,包括4×4哈达马变换和4×4离散余弦变换和反变换,能够达到每个时钟周期处理一个像素点的速度.使用SMIC 0.18 μm工艺对该并行结构进行了综合,电路面积为3757门,工作在100 MHz时钟频率下的关键路径为10.3 ms.     

Zero-Block Mode Decision Algorithm for H.264/AVC

In the previous paper , we proposed a zero-block intermode decision algorithm for H.264 video coding based upon the number of zero-blocks of 4 $,times,$4 DCT coefficients between the current macroblock and the co-located macroblock. The proposed algorithm can achieve significant improvement in computation, but the computation performance is limited for high bit-rate coding. To improve computation efficiency, in this paper, we suggest an enhanced zero-block decision algorithm, which uses an early zero-block detection method to compute the number of zero-blocks instead of direct DCT and quantization (DCT/Q) calculation and incorporates two adequate decision methods into semi-stationary and nonstationary regions of a video sequence. In addition, the zero-block decision algorithm is also applied to the intramode prediction in the P frame. The enhanced zero-block decision algorithm brings out a reduction of average 27% of total encoding time compared to the zero-block decision algorithm.      

基于H.264/AVC视频的低频隐写算法

在分析现有视频信息隐藏算法的基础上,结合H.264/AVC视频低频域系数的特征,提出一种基于H.264/AVC低频域视频信息隐藏算法。在量化后的离散余弦变换(DCT, discrete cosine transform)块低频区中,选取3个绝对值最大的非零系数,用改进的矩阵编码的方法嵌入信息。实验结果表明,该算法能够实现实时嵌入和提取信息,信息嵌入容量大,嵌入效率高,对视频质量影响较小等特点。     

Adaptive Scanning for H.264/AVC Intra Coding

In this letter, an adaptive scanning that improves intra coding efficiency in the H.264/AVC standard is proposed. The proposed adaptive scanning utilizes the prediction directions (modes) that include the horizontal and vertical edge information in a block. Depending on the prediction directions, the proposed method uses three scanning methods: zigzag scanning, horizontal scanning, and vertical scanning. In the proposed method, horizontal and vertical scanning are used in vertical and horizontal prediction modes, respectively, and the normal zigzag scanning in the H.264 standard is used in all other intra prediction modes. The proposed method reduces the bit rate by approximately 2.5% compared with H.264/AVC, without the degradation of video quality.     

H．264／AVC技术的应用研究

ITU—T和ISO联合开发的最新视频编码标准H．264／AVC具有压缩效率高、网络适应能力强等特点,对实现高效的媒体通信平台有着重要的工程意义和市场价值。介绍了H．264的技术特点、传输结构和编解码构架。提出了在Windows CE．NET操作系统下实现的一套H．264的实时解码软件系统。