共查询到17条相似文献,搜索用时 187 毫秒
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基于编码模式的H.264/AVC视频信息隐藏算法 总被引:4,自引:0,他引:4
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. 相似文献
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研究H.264的编码模式选择方案,根据视频序列的时域相关性和空域相关性的关系,模式选择包括帧内预测和帧间预测,帧间预测基于率失真函数,在一帧图像的编码中则可以采用提前终止预测方向的方法降低编码器端的复杂度. 相似文献
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一种基于预测模式的H.264/AVC视频信息隐藏改进算法 总被引:3,自引:0,他引:3
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... 相似文献
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《中国计量学院学报》2015,(1):123-128
高清、超高清视频编解码芯片结构设计中,原始图像帧和解码图像参考帧都存在外部存储器,外存访问带宽是系统设计的一大难题.通过图像压缩编码技术来降低图像冗余度,从而减小图像的存储容量和传输带宽.针对这一问题,提出了一种改进型无损图像压缩算法.与已有无损压缩算法相比,改进后算法以宏块为预测编码的基本单元,支持宏块随机访问;首先在预测部分加入块级预测与分层预测的自适应选择;然后在编码部分融入两种预测模式的半定长变长编码.实验结果表明,可降低带宽约50%. 相似文献
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《成像科学杂志》2013,61(3):311-319
AbstractIntra 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. 相似文献
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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. 相似文献
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Hongjin Zhu Honghui Fan Zhenqiu Shu Congzhe You Xiangjun Chen Qian Yu Pengzhen Gan 《计算机、材料和连续体(英文)》2020,65(3):2425-2439
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 computational
expenses 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. 相似文献
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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 Qr), we propose a Th_I‐Qr 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 Qr; 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 Qr 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 相似文献
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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%。 相似文献
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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. 相似文献
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自适应六边形-菱形运动估计算法及其在H.264中应用 总被引:1,自引:0,他引:1
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。 相似文献