Research Of Digital Video Watermarking Technology Based On MPEG-4

At present, as MPEG-4 video standard is widely used, there must be a technology such as digital watermarking to protect data copyright. However, MPEG-4 video standard has some special properties which make many video watermarking methods invalidated, so the research on the video watermarking algorithm with the new video compression standard has become the focus of the field of digital watermarking.On the basis of a great deal of information on video watermarking method and comparative analysis with the MPEG-4 standard features, two algorithms of video watermarking based on MPEG-4 streams are presented as follow:1. Combining the DCT and the MV, the low-frequency coefficients of watermarking image after discrete wavelet transform (DWT) were embedded in the low-frequency coefficients of I frame and the intermediate-frequency coefficients of the watermarking image were embedded in motion vectors of B frames.2. Based on MPEG-4 video compression principle and the human visual system model, an adaptive video watermarking algorithm is proposed. The adaptive factor is designed according to the direct current coefficient and the number of low and intermediate frequency coefficients after discrete cosine transform (DCT) of I frame. For different image blocks, the different embedded strength is used. The watermark is embedded into the low frequency coefficients.Based on the theory research, a video watermarking system based on MPEG-4 streams was implemented. The results show that the proposed algorithm is more robust and invisible than the original algorithm.