Research On Digital Watermarking For MPEG-4 Using Low Density Parity Check Coding

In recent years, with the information technology and computer networks development, as well as the multimedia technology progress, digital media has been widely applied in various fields, which brings great convenience to people's life. The new technology gives birth to new problems: information security threat and piracy that impede the further development of digital media and its applications. Copyright protection and against the piracy need to solve as the urgent problem. Protection for digital video watermarking technology has aroused widespread concern in society and developing rapidly.The paper expounds the research background of the issue, analyzing the feature of the video watermarking including the research status, basic concepts, basic principles, basic techniques, the development trends and application prospects. It introduces the MPEG-4 video standard and principle of the encoding and decoding algorithm, whose workflow is highlighted via the XviD Video CODEC source code. Besides, the flow diagram of some key processes and their brief instructions are given in this paper.By analyzing the existing classical watermarking algorithm, according to the comparability between the video watermarking system and digital communication system, a digital watermarking algorithm for MPEG-4 video based on LDPC coding is proposed. The watermark is embedded into and retrieved from the MPEG-4 video using the LDPC coding technique and human visual characteristics. The watermark is first encoded with LDPC before embedding into the intermediate frequency coefficients of the luminance components of the I-VOP. Each watermarking information is extended by the expansion coefficient. It can enhance the robustness of the watermarking. The watermark is retrieved blindly from the marked video using the LDPC iterative method. As a result of using the iterative decoding algorithm, which is a parallel algorithm, it can improve the decoding speed and reduce the complexity of decoding.Experimental results show that the scheme not only meets the visual masking, but also reduces the bit error rate in transmission process of the watermarking, and improves the anti-attack capability of the watermarking as compared with the spread-spectrum watermarking. In addition, the performance of the algorithm of the varied bit-rates is improved.