The Research Of Fast Video Bi-watermarking Technology Based On H.264 Standard

With the rapid development of digital technology and Internet, the problem of video data security is getting more serious. How to protect digital video copyright effectively has become an urgent issue in the video information security field. H.264 is a most promising coding standard because of its efficient coding performance, high image quality, and better network adaptability. The video watermarking algorithm based on H.264 has become the focus of research. Watermark embedding will lead to the increase of bit rate, and in the practical application it has high real-time demand on the watermarking algorithm. Therefore, the research of efficient watermarking algorithm to try to inhibit the bit rate increase, reduce algorithm complexity, and improve the real-time performance is meaningful and important.In this paper, we analysis the advantages and disadvantages of the typical watermarking algorithms from the practical application view of video protection technology. Base on this work, from the aspects of DCT,domain and motion vector, we proposed a fast arid real-time H.264-based watermark algorithm. This paper's major work is in the following two aspects:The first part of bi-watermarking algorithm is to achieve a robust watermark embedding in the DCT domain. The robust watermark introduces I-frame 4×4 block's energy E as a condition to embed robust watermark. Em is calculated corresponding to the median of DC coefficient in the sixteen 4×4 sub-blocks.Using the non-zero luminance coefficient of 4×4 block with energy higher than Em to embed the watermark information, and it can overcome the limitations of embedding watermark in the 4×4 block coefficient at a fixed location, also enhance watermark security performance. Robust watermark embedding needn't fully decoding. It has high real-time performance. In addition, the algorithm enhanced robustness and transparency of the watermark; also reduce the impact on bit rate by introducing the energy value E.The second part of bi-watermarking algorithm is to achieve fragile watermark embedding in motion vector domain. In practical application, considering video watermarking system has high demand on real-time and low-bit rate, this paper proposed a fragile watermarking algorithm based on Diamond Search. Fragile watermark was embedded in motion vector search of P frame inter prediction. We first reduce the scope of 1/4 pixel motion search elements, and then modify the accuracy of 1/4 pixel motion search to embed watermark information. The fragile watermarking algorithm improves real-time performance while reducing the impact on the bit rate due to narrow down the search area.