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1.
一种基于H.264/AVC的视频可逆脆弱水印算法 总被引:1,自引:0,他引:1
结合H.264压缩编码标准的特性,该文提出一种新的基于H.264/AVC的视频可逆脆弱水印算法。算法先计算当前宏块预测残差块量化的离散余弦变换(DCT)系数的哈希值生成认证码,再把认证码作为水印信息嵌入到下一个相邻宏块活性最大的44块的最后一个非零量化DCT系数中。在解码端,通过比较认证码和提取的水印信息进行视频数据完整性的认证。实验结果表明,该算法对视频质量和码率的影响较小,并且能对认证通过的视频数据进行还原和对认证失败的视频I帧遭篡改区域进行有效的定位。 相似文献
2.
Hai-Miao Hu Dong Jiang Bo Li 《Journal of Visual Communication and Image Representation》2009,20(1):35-44
With the rapid development of network and multimedia technology, the error control in video coding and video transmission over error-prone channels has become increasingly important. The DCT based predictive coding and VLC based entropy coding greatly increase the coding efficiency, but make the compressed video stream very sensitive to transmission errors. Therefore, this paper proposes a reliable error resilient video coding and video transmission framework. In order to improve the robustness to packet loss errors, an error resilient video coding algorithm named Z-FMO is proposed. Some channel may bring random bit errors, an adaptive error concealment algorithm based on macroblock boundary gradient namely ECMBG is proposed aiming at such problem. As the indispensable part of a video transmission system, we implement an adaptive video transmission control algorithm JCBAF. Experimental results show that the proposed framework performs well both in R-D performance and subjective quality. 相似文献
3.
《AEUE-International Journal of Electronics and Communications》2014,68(7):687-697
Based on the classical fractal video compression method, an improved object-based stereo video compression scheme with Shape-Adaptive DCT is proposed in this paper. Firstly, we use more effective macroblock partition scheme instead of classical quadtree partition scheme; thus reducing the block searching strategy. The stereo fractal video coding is proposed which matches the macroblock with two reference frames in left and right view results in increasing compression ratio and reducing bit rate when transmitting compressed stereo data. The stereo codec combines the Motion Compensation Prediction (MCP) and Disparity Compensation Prediction (DCP). Fractal coding is adopted and each object is encoded independently by a prior video segmentation alpha plane, which is defined exactly as in MPEG-4. The testing results with the nature monocular and stereo video sequences provide promising performances at low bit rate coding. We believe it will be a powerful and efficient technique for the object-based monocular and stereo video sequences coding. 相似文献
4.
《Signal Processing: Image Communication》2002,17(8):573-585
In this paper, we propose an efficient data partitioning and coding algorithm for an error-resilient transmission of DCT coefficients in error prone environment. In the typical data partitioning for Inter-coded frames, motion and macroblock header information is separated from the texture information. It can be an effective tool for the transmission of video over the error prone environment. For Intra-coded frames, however, the loss of DCT coefficients is fatal because there is no other information to reconstruct the corrupted macroblocks by errors. Conventional data partitioning algorithm for DCT coefficients is to separate a fixed number of the significant DCT coefficients from the remaining coefficients, called the spectral separation. While the spectral separation can guarantee an error resilient transmission with small overhead, the main drawback is a significant decrease in the image quality of the high priority partition, compared with that of the bitstreams without data partitioning for an equivalent bit-rate. In the proposed scheme, the quantized DCT coefficients are partitioned into an even-value approximation and the odd remainder part. We also propose a simple and efficient coding algorithm for the odd remainder part. It is shown that the proposed algorithm provides a better image quality than the conventional methods with a little overhead. 相似文献
5.
Scalable video coding incorporated with computation-aware ability achieves quality as well as being computation scalable. This paper presents a computation-aware algorithm for scalable video coding with spatial/quality scalability aiming for the best trade-off between rate distortion performance and computational consumption. We first observe and analyze and then establish a model for the motion vector difference relationship between the scalable base and enhancement layers. By using the modeling results, a linear algorithm for computation distribution is thus proposed to allocate the computation for each macroblock in the enhancement layer. In addition, the rate distortion costs of the base layer are also taken into account for the computation allocation process in order to further improve the coding performance. The simulation results demonstrate that our proposed computation-aware algorithm not only accomplishes better rate distortion performance than other works under the same computational constraints, but also achieves less computation necessities. 相似文献
6.
This paper defines and statistically calculates asymptotic computation in mode decision as a function of the quantization
parameters (QPs). Results reveal that computation savings are a monotonically increasing function of QP and that computation can be significantly reduced for large QPs. This study investigates and compares the computation cost in several mode decision algorithms with asymptotic computation.
Experimental results reveal that most of investigated algorithms are only suitable for high bit-rate coding, except for the
recently proposed zero-block decision algorithm that is similar to asymptotic computation. 相似文献
7.
Liquan Shen Zhi Liu Tao Yan Zhaoyang Zhang Ping An 《Signal Processing: Image Communication》2010,25(2):88-93
In the joint multiview video model (JMVM) proposed by JVT, the variable block-size motion estimation (ME) and disparity estimation (DE) have been employed to determine the best coding mode for each macroblock (MB). These give a high coding efficiency for multiview video coding (MVC), however, they cause a very high computational complexity in encoding system. This paper proposes to reduce the complexities of the ME and DE processes with an early SKIP mode decision algorithm based on the analysis of prediction mode distribution regarding the corresponding MBs in the neighbor view. In this method, the mode decision procedures of most of MBs can be early terminated, and thus much of computation for ME and DE can be greatly reduced. Simulation results demonstrate that our algorithm can achieve computational saving of 46–57% (depending on the tested sequences) with no significant loss of rate-distortion performance. 相似文献
8.
9.
This paper presents a deblocking method for video compression in which the blocking artifacts are effectively extracted and eliminated based on both spatial and frequency domain operations. Firstly, we use a probabilistic approach to analyze the performance of the conventional macroblock‐level deblocking scheme. Then, based on the results of the analysis, an algorithm to reduce the computational complexity is introduced. Experimental results show that the proposed algorithm outperforms the conventional video coding methods in terms of computation complexity while coding efficiency is maintained. 相似文献
10.
《Signal Processing: Image Communication》2004,19(4):299-312
In this paper, we propose a fast motion vector re-estimation for transcoding MPEG-1 to MPEG-4 with lower spatial resolution. This task can be performed in the pixel-domain or in the discrete cosine transform (DCT) domain. In this paper, we concentrate on the DCT-domain approach, which requires lower delay and complexity than those in the pixel-domain. For the DCT-domain transcoding to lower spatial resolution pictures, DCT-domain down-sampling filter is applied and a base motion vector (BMV) for the down-sampled MPEG-4 macroblock is to be calculated from the input motion vectors operating on the higher spatial resolution image. Quality can be significantly improved by refining the BMV. Starting with the BMV, the motion vector refinement (MVR) scheme searches for a delta motion vector within a significantly reduced search area. We propose a fast MVR scheme for video down-sampling in the DCT-domain based on minimizing the number of required check points, and a computationally efficient method for extracting motion compensated DCT block. We also show an efficient scheme for selecting a coding mode for a macroblock in the lower resolution video from those of the corresponding higher resolution video. 相似文献
11.
The authors present an efficient algorithm for the computation of the 4×4 discrete cosine transform (DCT). The algorithm is based on the decomposition of the 4×4 DCT into four 4-point 1-D DCTs. Thus, only 1-D transformations and some additions are required. It is shown that the proposed algorithm requires only 16 multiplications, which is half the number needed for the conventional row-column method. Since the 2m×2m DCT can be computed using the 4×4 DCT recursively for any m , the proposed algorithm leads to a fast algorithm for the computation of the 2-D DCT 相似文献
12.
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. 相似文献
13.
14.
This paper deals with the process of Transformation and Quantization that is carried out on each inter-predicted residual
block in a video encoding process and their reduced complexity hardware implementation. H.264/AVC utilizes 4 × 4 integer transform,
which is derived from the 4 × 4 DCT. We propose, a reduced complexity algorithm and a pipelined structure for the Core forward
integer transform module. A multiplier-less architecture is realized with less number of shifts and adds compared to existing
works. The corresponding inverse transform is exactly reversible. Each of the transformed coefficients is quantized by a scalar
quantizer. The quantization step size can be varied from macroblock to macroblock. The proposed unified pipelined architecture
outperforms many recent implementations in terms of gate count and is capable of processing a 4 × 4 residual block in 4 clock
cycles.
相似文献
Reeba KorahEmail: |
15.
For a conventional downscaling video transcoder, a video server has firstly to decompress the video, perform downscaling operations in the pixel domain, and then recompress it. This is computationally intensive. However, it is difficult to perform video downscaling in the discrete cosine transform (DCT)- domain since the prediction errors of each frame are computed from its immediate past higher resolution frames. Recently, a fast algorithm for DCT domain image downsampling has been proposed to obtain the downsampled version of DCT coefficients with low computational complexity. However, there is a mismatch between the downsampled version of DCT coefficients and the resampled motion vectors. In other words, significant quality degradation is introduced when the derivation of the original motion vectors and the resampled motion vector is large. In this paper, we propose a new architecture to obtain resampled DCT coefficients in the DCT domain by using the split and merge technique. Using our proposed video transcoder architecture, a macroblock is splitted into two regions: dominant region and the boundary region. The dominant region of the macroblock can be transcoded in the DCT domain with low computational complexity and re-encoding error can be avoided. By transcoding the boundary region adaptively, low computational complexity can also be achieved. More importantly, the re-encoding error introduced in the boundary region can be controlled more dynamically. Experimental results show that our proposed video downscaling transcoder can lead to significant computational savings as well as videos with high quality as compared with the conventional approach. The proposed video transcoder is useful for video servers that provide quality service in real-time for heterogeneous clients. 相似文献
16.
In this letter, we propose a novel bitrate control, using both Kalman and FIR filters, based on a Hamiltonian analysis with respect to the amount of bits from each macroblock, in an encoding of a general video codec such as H.264/AVC. Since the proposed bitrate control is based on the simple computation of an optimal control method based on the Hamiltonian analysis, it is not necessary to use additional computation, such as a DCT or quantization, to estimate the bits for bitrate control. As a result, the proposed algorithm can be applied to single‐pass encoding and can provide sufficient encoding speed with respect to various applications, even those requiring real‐time control. 相似文献
17.
Tiesong Zhao Hanli Wang Sam Kwong C.-C. Jay Kuo Wolfgang A. Halang 《Journal of Visual Communication and Image Representation》2011,22(7):627-633
To enable robust video transmission over heterogeneous networks, the hierarchical B-picture prediction structure is employed in the state-of-the-art video coding standard H.264/SVC, aiming to produce scalable bitstreams with various frame rates. However, the exhaustive mode decision process with the hierarchical B-picture structure increases the computational complexity of H.264/SVC encoding dramatically. In this paper, a fast mode decision algorithm is proposed to speed up H.264/SVC encoding with the hierarchical B-picture structure, which is achieved by utilizing macroblock (MB) features, correlation of temporal–spatial neighboring MBs, and the discrepant characteristics of hierarchical layers. Extensive experimental results demonstrate that the proposed algorithm is able to reduce the encoding time of H.264/SVC significantly for video sequences with a wide range of resolutions, and meanwhile the video quality and compression ratio are well preserved. 相似文献
18.
Zhenzhong Chen King N. Ngan Chengji Zhao 《Signal Processing: Image Communication》2003,18(10):879-887
Video streaming over wireless channel is challenging due to a number of factors such as limited bandwidth and loss sensitivity. In this paper, we develop a novel rate control algorithm for MPEG-4 video coding. Unlike traditional rate control schemes, we jointly consider the encoding complexity variation and buffer variation as well as human visual properties to optimize the rate control efficiency. We also analyze the sensitivity of a macroblock (MB) as a result of bit errors and calculate its error sensitivity metric. This metric is used in unequal error protection of the MB. Simulation results show that proposed approach can improve the decoded picture quality in wireless video coding and transmission. 相似文献
19.
多视点视频编码(MVC)采取可变块模式选择技术和 多参考帧技术显著提高了编码的压缩效率,但同时带来了巨大的 编码计算复杂度。为了降低MVC的计算复杂度,提出基于感知的快速MVC宏块模式选择 算法。基于人眼视觉感知的特点,利用视觉恰可察觉失真(JND)的概念建立MVC宏块的最优模 式和JND的联系,并利用该联系确定早期结束最优宏块模式选择过程的阈值,根据当前编码 宏块的JND与阈值的 关系自适应地减少每个编码宏块的模式搜索次数,进而减少MVC的方向搜索和参考帧搜索的 次数,以降 低编码的复杂度,提高MVC速度。实验结果显示,对于不同运动特性、内容、纹理信息、相 机间距和图像 尺寸的测试序列,提出的快速算法在率失真性能几乎不变的情况下平均节约76.00% 编码时间。 相似文献
20.
Adaptive Block-size Transform based Just-Noticeable Difference model for images/videos 总被引:1,自引:0,他引:1
Lin Ma King Ngi Ngan Fan Zhang Songnan Li 《Signal Processing: Image Communication》2011,26(3):162-174
In this paper, we propose a novel Adaptive Block-size Transform (ABT) based Just-Noticeable Difference (JND) model for images/videos. Extension from 8×8 Discrete Cosine Transform (DCT) based JND model to 16×16 DCT based JND is firstly performed by considering both the spatial and temporal Human Visual System (HVS) properties. For still images or INTRA video frames, a new spatial selection strategy based on the Spatial Content Similarity (SCS) between a macroblock and its sub-blocks is proposed to determine the transform size to be employed to generate the JND map. For the INTER video frames, a temporal selection strategy based on the Motion Characteristic Similarity (MCS) between a macroblock and its sub-blocks is presented to decide the transform size for the JND. Compared with other JND models, our proposed scheme can tolerate more distortions while preserving better perceptual quality. In order to demonstrate the efficiency of the ABT-based JND in modeling the HVS properties, a simple visual quality metric is designed by considering the ABT-based JND masking properties. Evaluating on the image and video subjective databases, the proposed metric delivers a performance comparable to the state-of-the-art metrics. It confirms that the ABT-based JND consists well with the HVS. The proposed quality metric also is applied on ABT-based H.264/Advanced Video Coding (AVC) for the perceptual video coding. The experimental results demonstrate that the proposed method can deliver video sequences with higher visual quality at the same bit-rates. 相似文献