Object based watermarking for H.264/AVC video resistant to rst attacks

In this paper, a compressed domain video watermarking scheme is proposed which embeds the watermark in the homogeneous moving object within a shot of video sequence to resist geometric attacks such as rotation, scaling etc. Intuitively, object based watermarking results low payload and has the least impact on visual quality since the object area is generally small and highly textured. The proposed work has two main contributions, firstly, an existing compressed domain motion coherent block detection algorithm [7] is extended to detect the moving objects within a video shot and secondly, a watermarking scheme has been proposed by embedding within the moving objects to resist RST attacks. A comprehensive set of experiments has been carried out to justify the applicability of the proposed scheme over the existing literature.     

Robust H.264/AVC video watermarking without intra distortion drift

Multimedia Tools and Applications - A robust H.264/AVC video watermarking algorithm without intra distortion drift is proposed in this paper for the copyright protection of digital videos. The...     

Perceptual differential energy watermarking for H.264/AVC

This paper presents a novel watermark embedding scheme for H.264/AVC video using a spatio-temporal just-noticeable difference (JND) model, which is based on 4?×?4 DCT blocks. Combined with the proposed JND model, a previous differential energy watermarking (DEW) algorithm is modified for better imperceptibility. Low-density parity-check (LDPC) and spread spectrum are used to enhance robustness of the watermark. The watermarked video has good robustness against common video attacks such as re-compression, additive white Gaussian noise (AWGN), salt-and-pepper noise, Gauss filtering, circular averaging filtering and frame averaging. The watermarked video also has good visual quality due to the introduced JND model.     

一种基于H.264的鲁棒视频水印算法

由于H.264标准视频的流行,对数字视频水的版权保护和认证的需求在不断增加。本文提出了一种基于H.264视频编解码标准的鲁棒视频水印算法。水印经过了增加帧同步信息,扩频编码和纠错编码的预处理后有着很强的鲁棒性。在嵌入过程中,选择了残差的DCT系数与参考块像素的DCT系数和作为嵌入载体,而不是通常的残差DCT系数,该处理可以很好的提高水印算法对视频攻击,如帧率攻击和码率攻击的鲁棒性,同时在嵌入的过程中,通过应用一个针对4*4的DCT的人类视觉系统来控制嵌入强度,使得水印算法对视频的视觉质量的影响降到最小。实验结果表明:本算法对多种攻击,如分辨率攻击、帧率攻击、码率攻击和重编码都有很好的鲁棒性,同时能保持很高的视觉质量。     

Incremental rate control for H.264/AVC video compression

In this study, the authors propose a new rate-complexity-quantisation model and an incremental rate control algorithm for H.264/AVC video coding. One unique property of this algorithm is that, the picture complexity estimation and rate-quantisation modelling are jointly designed with an incremental rate control for P-frames. In addition, the proposed algorithm also introduces a number of efficient rate control techniques, including accurate rate control for intra-frames, enhanced proportional--integral--derivative (PID) buffer controller, and adaptive quantisation parameter determination for B-frames. The proposed algorithm has low computational complexity while providing robust rate control. Our extensive experimental results demonstrate that the proposed algorithm outperforms the current rate control algorithm adopted in the H.264/AVC reference software JM13.2 by achieving more accurate rate control, reducing frame skipping, depressing quality fluctuation and improving the overall coding quality by up to 2.83 dB.     

Mixed architectures for H.264/AVC digital video transrating

In this paper, we investigate transrating architectures for H.264/AVC video streams. Basic architectures are presented with their strengths and weaknesses. None of the existing architectures provide an appropriate solution for H.264/AVC transrating with an optimal balance between visual quality and complexity. In order to find such an appropriate solution, we propose the use of mixed transrating architectures. These architectures combine different transrating techniques which are applied depending on the picture/macroblock type. The intra-predicted pictures are decoded and re-encoded, while open-loop transrating or transrating with compensation is applied to motion-compensated pictures. Performance results show that the mixed architecture which applies spatial compensation to motion-compensated pictures gives rate-distortion results which approach the cascade of decoder and re-encoder with a complexity only slightly higher than the open-loop transrater. Adding temporal compensation for motion-compensated pictures further improves the visual quality, albeit to a lower extent, at the expense of increased complexity.

Low-delay rate control for real-time H.264/AVC video coding

This paper presents an efficient rate control scheme for the H.264/AVC video coding in low-delay environments. In our scheme, we propose an enhancement to the buffer-status based H.264/AVC bit allocation method. The enhancement is by using a PSNR-based frame complexity estimation to improve the existing mean absolute difference based (MAD-based) complexity measure. Bit allocation to each frame is not just computed by encoder buffer status but also adjusted by a combined frame complexity measure. To prevent the buffer from undesirable overflow or underflow under small buffer size constraint in low delay environment,the computed quantization parameter (QP) for the current MB is adjusted based on actual encoding results at that point. We also propose to compare the bits produced by each mode with the average target bits per MB to dynamically modify Lagrange multiplier (/spl lambda//sub MODE/) for mode decision. The objective of QP and /spl lambda//sub MODE/ adjustment is to produce bits as close to the frame target as possible, which is especially important for low delay applications. Simulation results show that the H.264 coder, using our proposed scheme, obtains significant improvement for the mismatch ratio of target bits and actual bits in all testing cases, achieves a visual quality improvement of about 0.6 dB on the average, performs better for buffer overflow and underflow,and achieves a similar or smaller PSNR deviation.     

Reversible data hiding based on a modified difference expansion for H.264/AVC video streams

Reversible Data Hiding (RDH), also referred to as invertible or lossless data hiding, has gradually received much attention from the research community in recent years. In this paper, a RDH scheme for H.264/AVC videos is proposed and it is based on a novel way to expand the difference of a pair of Quantized Discrete Cosine Transform (QDCT) coefficients. The secret data is embedded into the QDCT coefficients of 4?×?4 luminance blocks which selected according to two conditions to achieve good visual quality. In every embeddable 4?×?4 blocks each to- be-embedded information bit is embedded into the selected coefficient-pair. All the selected coefficient-pairs are changed by the proposed difference expanding strategy, which causes low distortion on visual quality. Experimental results have demonstrated that the proposed scheme obtains a little degradation of visual quality and keeps the variation low in bit-rate increase.

     

Effectiveness of crypto-transcoding for H.264/AVC and HEVC video bit-streams

Multimedia Tools and Applications - To avoid delays arising from a need to decrypt a video prior to transcoding and then re-encrypt it afterwards, this paper assesses a selective encryption (SE)...     

The problems in digital watermarking into intra-frames of H.264/AVC

Differently from other image/video compression techniques, it is not easy to find a successful watermarking scheme for H.264/AVC. Thus we, as the researchers on digital watermarking, intend to find the reason(s) of the hardness in this paper. Among the various techniques in H.264/AVC we only concern the intra-prediction in this paper, which is the main technique to form an intra picture. We closely examine the properties of intra-prediction in the aspect of digital watermarking.     

H.264中自适应二进制算术编码的IP核设计及其FPGA验证

阐述H.264/AVC二进制算术编码的原理,论述此编码的IP核设计方案及其FPGA验证。整个设计使用VerilogHDL语言描述,在ALDEC的Active_HDL6.2平台上进行时序仿真,在Synplicity的Synplify7.0平台上进行综合。设计充分利用了硬件并行性,并进行关键路径优化和复用器重构算法优化,通过实际验证证明了设计的高效性和可行性。     

Improved parabolic prediction-based fractional search for H.264/AVC video coding

In this study, the authors propose an efficient fractional pixel search algorithm for H.264/AVC video coding to reduce the computational complexity in half/quarter-pixel motion estimation. A prediction for the optimal motion vector is derived under the assumption that the sum of absolute transform differences error surface is a symmetric parabolic function. With the optimal region, a decision rule for half-pixel search is proposed. The experimental result shows that approximately two search points are required. Based on the half-pixel search, a hierarchical quarter-pixel search is described and an extra three search points, on average, are consumed for each quarter-pixel search. Experimental results show that significant reduction in computation can be achieved, while maintaining high coding efficiency.     

A novel steganography scheme for video H.264/AVC without distortion drift

Multimedia Tools and Applications - Many steganography schemes have been proposed for video sequences. However, the embedding capacity obtained by these schemes is still unsatisfactory. In this...     

Low-complexity quantization for H.264/AVC

In this paper, an improved quantization technology with low-complexity is presented for H.264/AVC video codec. Multiplication factors of H.264/AVC quantizer are modified. Therefore, it is possible to reduce the bit width of the quantization and substitute large bit-width multiplier by some small bit-width adders without noticeable rate-distortion degradation in integrated circuits (ICs) design. Quantization error introduced by the modified multiplication factors is not only theoretically but also experimentally analyzed. Quantizer is optimized on register transfer level of IC design, and under the same cell CMOS technology, about 75.2% area and 76.3% dynamic power consumption are saved in each quantization unit on average compared with original H.264/AVC quantization. Experimental video coding results show that the Bjontegaard delta peak signal-to-noise ratio (PSNR) and Bjontegaard delta bit rate between the improved and original H.264/AVC quantization are very slight, which means that the improved quantization scheme is approximately the same as the original quantization scheme of H.264/AVC in rate-distortion performance.

Fast video transcoding from H.263 to H.264/MPEG-4 AVC

In the past 10 years detailed works on different video transcoders have been published. However, the new ITU-T Recommendation H.264—also adapted as ISO/IEC MPEG-4 Part 10 (AVC)—provides many new encoding options for the prediction processes that lead to difficulties for low complexity transcoding. In this work we present very fast transcoding techniques to convert H.263 bitstreams into H.264/AVC bitstreams. We will give reasoning, why the proposed pixel domain approach is advantageous in this scenario instead of using a DCT domain transcoder. Our approach results in less than 9% higher data rate at equivalent PSNR quality compared to a full-search approach. But this rate loss allows the reduction of the search complexity by a factor of over 200 for inter frames and still a reduction of over 70% for intra frames. A comparison to a fast search algorithm is given. We also provide simulation results that our algorithm works for transcoding MPEG-2 to H.264/AVC in the aimed scenario.

Fast macroblock mode decision for H.264/AVC baseline profile video transcoder based on support vector machines

In video transcoding, accuracy and efficiency of macroblock mode decision are critical issues at the re-encoder side due to the changes in frame size, frame rate, and bit rate. In this paper, a fast macroblock mode decision scheme based on support vector machines is proposed for H.264/AVC baseline profile video transcoder. Features including motion vectors, residual data, pre-encoded macroblock modes, and quantization parameters are extracted from incoming bitstream in both of training stage and classification stage. Feature extraction methods are investigated for spatial resolution transcoder, temporal resolution transcoder, and bit-rate transcoder. After off-line training and simplification of support vectors, the obtained support vector machine classifier can determine macroblock mode in the re-encoder accurately. Extensive experiments are carried out on different types of transcoders and results show that the proposed method can save about 80% in computational complexity compared to full mode search algorithm implemented in the latest H.264/AVC reference software (JM17.1), while maximum peak signal-to-noise ratio is degraded by 0.2–1.1?dB depending on different sequences and bit rate.