基于帧间共谋的视频隐写分析

基于视频序列的时域特性,提出一种应用帧间共谋策略的视频隐写分析算法.分析了视频序列中所含局部运动对隐写分析检测精度的干扰,将秘密信息和局部运动建模为双模噪声,据此提出基于视频帧间分块相关度的特征提取策略.隐写分析算法依据提取的特征应用GRNN分类器进行视频帧的分类,以识别含秘密信息的可疑视频帧,在一定程度上降低了局部运动的影响.实验结果表明该算法可实际应用于视频隐写分析.     

基于H.264宏块内码率控制的隐写算法

在H.264/AVC视频编码标准框架下,提出一种基于H.264宏块内码率控制的视频隐写算法,根据CSF函数对DCT变换频率进行分类,判别DCT变换块的不敏感频率,并对DCT块进行分类,最后通过秘密信息比特位指导DCT块不敏感频率系数的舍弃和选取。实验中进行了隐写容量测试、信噪比损失测试和视频压缩码流大小测试。实验表明,该算法在损失信噪比较小的情况下能嵌入较多的信息,并能保持原视频编码器的压缩特性。     

基于差值分析的视频隐写分析

隐写分析主要是针对图像、视频、声音等多媒体数据,在对隐写算法和隐藏信息一无所知的情况下,仅仅通过分析多媒体数据,检测其是否含有隐藏信息。提出一种对视频基帧信息进行差值分析的方法,来检测视频中是否携带隐藏信息,并利用MPEG视频文件的编解码源代码库ffmpeg,对实际视频进行了大量的分析实验,实验结果表明,对于不同的视频对象和水印嵌入率,该算法都可有效检测到隐藏信息。     

基于Linphone的海思H.264硬件编码器移植

为了缩短H.264编码时间、提高H.264编码效率,提出基于Android Linphone的Hi3716MV400 H.264硬件编码器移植.对硬件编码器的移植方法进行详细说明,包括搭建Linphone开发环境、添加Hi3716MV400 H.264硬件编码库、编写H.264硬件编码函数.经程序测试,移植了海思H.264硬件编码器的Linphone能够在Hi3716MV400机顶盒进行正常的视频通信,并且减少CPU资源占用,降低Linphone视频通话死机频率.     

基于图像的广义隐写分析

主要对基于图像的广义隐写分析算法进行了研究,选取4种对信息隐藏分析效果最好的图像质量度量标准(Image Quality Metrics),运用误差反传(Back Promulgate)神经网络设计了一套广义隐写分析系统,并将其用于最终隐写图像的检测分类上.经实验证明,该方法具有较高的准确率和普遍的适应性,因而可用于实际的隐写图像检测分析中.     

H.264压缩域中mean-shift聚类运动目标分割算法

针对视频监控、检索,提出了一 种在H.264压缩域下运动对象分 割的新算法。根据实际监控应用特点,算法主要利用H.264码流中提 取的运动矢量(MV)、分块尺寸信息对原始的MV场(MVF)进 行可靠性分析以及空间滤波、mean-shift聚类处理,从而得到可信度较高的 MVF场。首先,从H.264码流中获取原 始MV 并进行归一化处理,同时对原始MVF进行两步空间滤波;其次,对不同的块大 小分配相应的权值作为每个样本 的权重系数,将处理之后的MVF作为样本空间,利用mean-shift聚类获取 真实的MVF;最后,根据可靠的MVF 标记运动目标。实验结果表明,本文提出的mean-shift聚类运动目标分割算 法可以获得有效并可靠的分割结果。     

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。     

基于H.264的漂移深度控制视频隐写算法

在H.264/AVC视频压缩域隐写技术中,失真漂移问题极大地影响了信息嵌入的容量和稳定性.本文结合工程实际和实验,发现并指出了漂移传播的实质性规律,提出了相应的改进策略.首先,提出了漂移分级的控制策略,依据不同视频质量及隐蔽性要求自适应地调整失真漂移的传播范围,改进了视频隐写的隐蔽性和安全性;进而通过对漂移影响分层分析,挖掘出了更多的隐写位置,增加了隐写容量及选择隐写方案的灵活性.形成了一种新的扩容视频隐写算法--漂移深度控制算法.实验结果和分析表明,该算法能有效地减小嵌入偏移,隐写容量、视频质量及安全性都有较大提升.     

一种低比特率增长的H.264视频信息隐藏算法

提出一种基于预测模式调制的H.264视频信息隐藏算法。在H.264视频的帧内预测过程,通过调制I帧4×4亮度块的帧内预测模式实现隐秘信息的嵌入。调制方法是基于宿主4×4亮度块的边缘强度(DES)划分的映射规则进行的,从而避免了信息隐藏后视频流的比特率的过快增长。同时,通过结合矩阵编码技术使得修改一个预测模式可以隐藏4bit信息。在信息提取过程中,不需要对含密视频进行完全解码,只需获取含密视频的帧内预测模式即能提取秘密信息。实验结果表明,本文算法在提高隐藏容量和保证视频质量的同时,也有效避免了比特率的过快增长。     

基于H.264/AVC的自适应视频错误隐藏技术算法

针对帧内错误隐藏,研究了基于边缘检测的错误隐藏算法,提出了根据丢失块特点自适应的选择基于边缘检测错误隐藏算法或H.264的空间像素加权平均算法。通过在MATLAB平台上对几种视频错误隐藏算法进行仿真测试,结果表明这种自适应的视频错误隐藏算法在主客观效果上都有所提高。     

基于预测模式相关性的HEVC隐写检测算法

提出了一种基于预测模式相关性的高效视频编码(HEVC)隐写检测方法。首先定义帧内预测模 式相关性的概念;然后通过实验,分析 隐写前后帧内4×4亮度块中35种帧内预测模式 的相关性统计数据的变化情况;最后选择35个隐写前后变 化较大的相关性数据构成视频特征,并利用支持向量机(SVM)分类器进行隐写检测。实验表 明,本文检测 方法的特征维数低,计算复杂度小,对修改帧内预测模式的隐写算法具有良好的检测效果。     

Steganalysis of prediction mode modulated data-hiding algorithms in H.264/AVC video stream

In the intra-frame coding of H.264/AVC, information hiding can be implemented by modulating the prediction modes of 4?×?4 luminance blocks. Because such kind of methods has characteristics of high speed, good concealment, and so on, it is very suitable to build the covert communication system based on video communications and brings a great public security threat. Therefore, it is important to study its steganalysis method. In this paper, we first analyzed the changes of remarkable characteristics in intra-frame coding caused by modulating intra-prediction modes for information hiding, and found that the inherent correlation among the prediction modes in different 4?×?4 luminance blocks belonging to an intra-frame coding macroblock was changed. According to several different positional relationships of the adjacent 4?×?4 blocks in spatial domain, we designed statistical models corresponding to the prediction mode correlation to make quantitative extraction of these correlation characteristics. An information hiding detector was constructed based on the support vector machine. Based on the constructed detector, the experimental results show that the mean of the detection accuracy, recall ratio, and precision ratio are all excellent for different test video sequences.     

A motion vector recovery algorithm for digital video using Lagrange interpolation

In this paper, we propose an efficient motion vector recovery algorithm for the new coding standard H.264, which makes use of the Lagrange interpolation formula. In H.264, a 16/spl times/16 inter macroblock can be divided into different block shapes for motion estimation, and each block has its own motion vector. For nature video the movement within a small area is likely to move in the same direction, hence the neighboring motion vectors are correlative. Because the motion vector in H.264 covers smaller area than previous coding standards, the correlation between neighboring motion vectors increases. We can use the Lagrange interpolation formula to constitute a polynomial that describes the motion tendency of motion vectors, which are next to the lost motion vector, and use this polynomial to recover the lost motion vector. The simulation result shows that our algorithm can efficiently improve the visual quality of corrupted video.     

基于帧内预测模式的H.264/AVC视频信息嵌入算法

提出了一种基于帧内预测模式的H.264/AVC视频信息嵌入算法.在秘密信息进行嵌入时,根据人类视觉特性的掩蔽效应,筛选出I帧中纹理密集区域的4×4亮度块,确定为嵌入块.通过秘密信息调制4×4亮度块的预测模式最低有效位,完成秘密信息的嵌入.通过对算法进行仿真实验,证明本算法计算量小,能够实时处理.对视频载体影响小,有一定的嵌入容量,能够保证秘密信息的有效传输.     

An improved reversible data hiding-based approach for intra-frame error concealment in H.264/AVC

As H.264/AVC video streams are highly compressed, they become sensitive to errors caused by unreliable transmission channels. In order to address this issue, an improved version of Chung et al.’s reversible data hiding-based approach for intra-frame error concealment is proposed for H.264/AVC codec. By using the histogram shifting technique, the original work reversibly embeds the motion vector (MV) of a macroblock (MB) into other MB within the same intra-frame. If an MB is corrupted at the decoder side, the embedded MV can be extracted from the corresponding MB for the recovery of the corrupted MB. However, Chung et al.’s work did not fully exploit the number of coefficients which need to be modified in order to reversibly hiding data, and did not consider many extra nonzero residual blocks produced by data hiding. These two issues could reduce the visual quality of the stego-video. This paper adopts MV data pre-processing, the selection of most suitable embedding region, and the minimum possible amount of histogram modification, which lead to higher PSNR of the stego-video for a given payload. Experimental results further reveal that the proposed method offers stego-video with better visual quality over Chung et al.’s work.     

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。     

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.     

基于H.264运动估计算法的改进与优化

在H.264视频编码标准中,运动估计是最重要也是最耗时的过程,目前H.264标准中采用UMHexagons算法,本文结合H.264的验证模型在JM8.6的源代码上对UMHexagons进行分析,利用视频图像序列运动矢量的分布规律以及当前块像素之间运动估计代价的相关性,对搜索模板和搜索步长进行改进,从而提前结束搜索,减少运动估计时间,实验结果表明:改进后的算法在保证性噪比(PSNR)变化不大的前提下,运动估计时间降低10%以上。     

Fast Interframe mode decision algorithm based on mode mapping and MB activity for MPEG-2 to H.264/AVC transcoding

Recently the latest video coding standard H.264/AVC is widely used for the mobile and low bitrate video codec in the various multimedia terminals. On the other hand, the MPEG-2 MP@HL codec has become the center of digital video contents since it is the standard codec for the Digital TV (DTV). To provide the bridge between the contents in MPEG-2 and mobile terminals, the transcoding of MPEG-2 contents into H.264/AVC format is an inevitable technology in the digital video market. The main bottleneck in the process lies in the computational complexity. In H.264/AVC, the variable block size (VBS) mode decision (MD) is used in the Interframe for the improved performance in the motion compensated prediction. For the macroblock (MB) which cannot be accurately predicted with one motion vector (MV), it is partitioned into smaller blocks and predicted with different MVs. In addition, SKIP and Intra modes are also permitted in the Interframe MD of H.264/AVC to further ameliorate the encoding performance. With the VBS MD technology, the Inter prediction accuracy can be improved significantly. However, the incidental side-effect is the high computational complexity. In this paper, we propose a fast Interframe MD algorithm for MPEG-2 to H.264/AVC transcoding. The relationships between SKIP and Intra modes are detected at first to map these two kinds of modes directly from MPEG-2 to H.264/AVC. And then the MB activity will be scaled by the residual DCT energy obtained from the MPEG-2 decoding process to estimate the block sizes of the MB mode for H.264/AVC Interframe MD. In our proposed method, the original redundant candidate modes can be eliminated effectively, resulting in the reduction of the computational complexity. It can reduce about 85% Rate-to-Distortion Cost (RDCost) computing and 45% entire processing time compared with the well-known cascaded transcoder while maintaining the video quality.