Watermarking of uncompressed and compressed video

In this paper, methods for embedding additive digital watermarks into uncompressed and compressed video sequences are presented. The basic principle borrows from spread spectrum communications. It consists of addition of an encrypted, pseudo-noise signal to the video that is invisible, statistically unobtrusive, and robust against manipulations. For practical applications, watermarking schemes operating on compressed video are desirable. A method for watermarking of MPEG-2 encoded video is presented. The scheme is a compatible extension of the scheme operating on uncompressed video. The watermark is generated exactly in the same manner as for uncompressed video, transformed using the discrete cosine transform (DCT) and embedded into the MPEG-2 bit-stream without increasing the bit-rate. The watermark can be retrieved from the decoded video and without knowledge of the original, unwatermarked video. Although an existing MPEG-2 bit-stream is partly altered, the scheme avoids visible artifacts by addition of a drift compensation signal. The proposed method is robust and of much lower complexity than a complete decoding process followed by watermarking in the pixel domain and re-encoding. Fast implementations exist which have a complexity comparable to a video decoder. Experimental results are given. The scheme is also applicable to other hybrid transform coding schemes like MPEG-1, MPEG-4, H.261, and H.263. (C) 1998 Elsevier Science B.V. All rights reserved.