Research On Algorithms Of Digital Video Watermarking Based On H.264for Copyright Protection And Content

In recent years, with the rapid development of HD digital TV and VOD (video on demand) technology accompanied by the popularity of multimedia sharing site, video multimedia has gradually become a significant part in people’s daily life. Thus, the efficient methods for copyright protection and content authentication of digital video have been research hotspots in academic field of multimedia security.Because of the large amount of data, video need to be compressed in the process of storing and transferring and H.264/AVC is the most popular encoding and decoding standard on market nowadays, which makes the demand for video watermarking based on H.264/AVC more and more urgent.Analysizing on the shortcomings of the existing video watermarking algorithms based on H.264/AVC and considering the properties of H.264/AVC and HVS (Human Visual System), this articlefocuses on video robust watermarking used for copyright protection and fragile watermarking and semi-fragile watermarking used for content authentication.The comprehend content of this research is consisted by energy-differential video watermarking algorithm based on textural features, video robust watermarking based on JND model, H.264real-time reversible fragile watermarking algorithm based on content features and semi-fragile watermarking algorithm based on error compensation strategy. And the main innovation points of this article could be concluded as following:Firstly, to solve the problem of robustness insufficiency of video watermarking based on H.264/AVC caused by only embedding lbit watermark in one coefficient of macro-block, this article put forward a new energy-differential video watermarking algorithm based on textural features by considering the properties of H.264compressing and encoding standard. The proposed algorithm firstly performs the4x4integer Discrete Cosine Transform on the current frame in purpose of identifying whether it is the texture block. Then the watermarking is embedded by adopting the way of differential energy for selecting the appropriate coefficients adaptively. The experimental result shows that the proposed algorithm has little impact on the video quality and bit-rate, moreover, its robustness can effectively resist the common attacks such as the gauss noise, low pass filter and re-coded performed on the video watermarking.Secondly, the existing JND models based on8x8floating point DCT transform can’t be directly applied to video watermarking algorithms based on H.264/AVC because of which adopts the4x4integer transform. After analyzing on the shortcomings of the existing JND models based on the4×4integer transform, the article proposes a new and more accurate JND model. Since not all of the JND values of integer DCT coefficients which arelarger than the quantization are suitable for embedding watermarks, after researching the embedding position for watermarks, we come to a conclusion that the DC and low-frequency component of the DCT coefficients of the quantized residual blocksare not suitable for embedding watermarks, and the theoretical analysis and experimentsshow that our conclusion is reasonable. In order to improve the robustness of watermarking, we propose different watermarking embedding and extraction algorithmsaccording to the different frequency ranges of DCT coefficients. The proposed watermarking algorithm not only meetsthe imperceptibility and robustness requirement, but also has highembedding capacity.Thirdly, the majority of existing fragile video watermarking algorithms based on H.264/AVC are irreversible. We analyze the reasons and propose a real-time reversible fragile video watermarking based on content features. The proposed algorithm firstly performs the hash value of quantized DCT coefficients of predictive residue blocks in current macro-block, and then creates the authentication code. And after that, embed the code into the last nonzero quantized DCT coefficient in the most active4×4block of the next adjacent macro-block as watermark information in the reversible manner. The integrality authentication is carried out and the original data isrestoredint thethe decoding end by the comparison of the authentication code and the extracted watermark information. The experimental result shows that the proposed algorithm has little impact on the video quality and bit-rate, moreover, the original video can be recovered if the authentication is successful and the tampered area of I frame can be effectively located if the authentication fail.Fourthly, to further improve the robustness of the feature codes in semi-fragile video watermarking algorithm, we propose a new generation algorithm for feature codes by eliminating the correlation of them. In order to meet the requirement that the semi-fragile watermarks should be uniformly embedded into the video frames to locate the tampered region accurately, this paper introduces a minimal distortion selection function to select a DCT coefficientin the4×4block residualto embed watermark which has minimal impact on the video quality and bit rates.compared with existing algorithms, the proposed algorithm can significantly reduce impact on video quality and bit rate because of embedding the watermarking by adopting the minimum distortion selection function. Experimental results show that the scheme has robustness against the content-preserving manipulations and it is sensitive to malicious manipulations. What’s more, the retrieved feature code and watermarking can detect and locate malicious manipulations.