Based On Research And Realization Of Video Watermark Technology For MPEG-4

In this paper, applications of watermarking video content and main technical thoughts in video watermarking are studied. The inevitability of the combination between video watermarking and compress standard is discussed. The realistic meaning and market prospects of MEPG-4 watermarking and new technical constraints introduced by MPEG-4 coding are analyzed.Several algorithms for MPEG-4 watermarking are studied. A method for watermarking of MEPG-4 compressed video is presented. Spread spectrum technology is used to improve the security of watermark sequences. A synchronization template is used to combat geometrical distortion such as cropping, scaling, and rotation. Both signals, synchronization and watermark, are embedded in the bit stream. A drift compensator is used to eliminate the distortion due to AC/DC prediction in I-VOPs and motion compensation in P-VOPs and B-VOPs, to maintain robustness of the watermark and the quality of the video, and resist format conversion attack. A bit stream control mechanism is introduced to maintain the data rate after the embedding manipulation. From the experiment results, it indicates that, after the watermarked MPEG-4 video suffer filtering, rotation, scaling and transcoding, the watermark possesses good imperceptibility and robustness.