Watermarking Technology In Video On Demand

With the development of digital technology, video and any other multimedia digital objects can be easily modified. Furthermore, the rapid growth of Internet facilitates the transmission of digital data. Thus, the security of multimedia data is threatened. 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, focused on that the digital watermarking must meet some requirements in applications. After deeply analyzing the technical characters of video watermarking and existed related work, we propose a novel watermarking algorithm for MPEG-I/II encoded video based on block classification technique. The scheme is of much low complexity and can be implemented in some real-time applications such as Video On Demand(VOD)system. Thanks to the exploitation of MPEG video coded techniques, the scheme we presented is able to withstand a variety of attacks, such as rate shaping, re-quantization and re-encoding. Meanwhile, in order to preserve the video quality, perceptual models are considered during the embedding process.Video authentication is expected to prove the integrity of the content. Common authentication techniques do not allow any form of manipulation, thus making it impractical for some applications. In this thesis, we propose an authentication scheme that can survive the trans-coding method by using digital signature as watermark. Nowadays, videos are only available in compressed format in many applications, so we focus on the authentication of MPEG video. The experimental results show that the proposed techniques are not only efficient to protect integrity of MPEG-I/II video, but also are feasible for applications.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.