Study On Video Digital Watermarking Algorithm Based On MPEG-4

With the rapid development of modern computer and Internet technology, it is more and more easy to access, duplicate and spread the digital multimedia works, which makes the copyright of digital multimedia works damaged seriously and heavily damages the benefits of the owner. So multimedia intellectual property protection becomes an urgent problem to be solved.As a new and effective approach to solve the problem of copyright protection, digital watermarking has emerged to be an active and flourishing research topic in the field of information security recently. Digital watermarking technique protects the digital works by embedding unperceivable and secret information into digital works, which has no effect upon the using of the digital works. Generally, it demands three basic characters of imperceptibility, robustness and security. In the kinds of digital watermarking techniques, researchers have paid more attention to video watermarking technique because of its high research value and potential commercial profits. However, current video watermarking technique is far beyond mature compared with the still image watermarking.This thesis systematically summarizes the concepts, framework and the typical applications of watermarking technique. It also introduces the characteristics, research status, speciality, classifications and benchmarks of video watermarking techniques in detail.This thesis focuses on video watermarking algorithms based on MPEG-4 and experiments are performed to test the effectiveness of the proposed algorithm. The main research work and contributions of this thesis are summarized as follows:①This thesis deduces the period of Toral transform in detail and proposes an algorithm to calculate the period of Toral transform. The algorithm is implemented in Microsoft Visual C++ 6.0 integrated development environment by C language.②Because the currently available watermarking algorithms based on error correcting code can not combine the blind watermark technique with soft-decision decoding technique, this thesis proposes a blind watermarking algorithm which is suitable for soft-decision and can effectively improve the robustness of watermark. The validity of proposed algorithm is tested in image and the range of quantization step in the algorithm is also discussed by deduction and experiment. Then the proposed algorithm is embedded in MPEG-4 video CODEC and experimental results show that error correcting code can effectively improve the robustness of watermark and soft-decision decoding is better than hard-decision decoding. In addition, the real-time processing demand is also satisfied.③According to the proposed algorithm, a watermark embedding/extracting software is developed in Microsoft Visual C++ 6.0 integrated development environment by C/C++ and MFC.