Application Study Of Digital Watermark Technique In VOD

With the development of digital technology ,video and any other multimedia digital objects can be easily modified. Meanwhile, the rapid growth of Internet facilitates the transmission of digital data. Thus ,the security of multimedia data is threatened and the interest of authors and copyright owners are harmed. The protection and authentication of multimedia data is becoming an important issue. Digital watermarking has been proposed as an effective solution to solve the security problem of multimedia. The technique is feasible as a tool for copyright protection, the tracking of illegal reproductions ,the proof of ownership and integrality authentication on multimedia materials.In this thesis, firstly we introduce the origin and development of digital watermarking, the characteristics and some application fields of this technique, combining with the characteristics of VOD system ,we sum up the requirements of watermarking in the real VOD system. After analyzing the technical characters of video watermarking ,frameworks and models, typical algorithms ,we set the focus on application of watermarking on VOD and propose an innovative watermarking algorithm for MPEG-4 encoded video based on mid- and high-pass band of wavelet transform . This is put forward after considering the extensive application of MPEG-4 in the field of digital video. The scheme is of high complexity and can be tested to implement in some real-time applications such as Video On Demand system. Thanks to the exploitation of MPEG video coded techniques ,the scheme we presented is able to withstand a variety of attacks. Meanwhile, in order to preserve the video quality .perceptual models are considered during the embedding process.Using Matlab to do experiments, the results have proved that the method is robust enough to some image degradation process after comparison of watermarking extracted from video pictures after mid- and hige-pass bands of wavelet transform. Finally ,a summary about the unsettled problems in digital watermarking field is given out and a further research orientation in the future is pointed out.