抄録
We developed a technique for watermarking an MPEG-2 video stream. Our method keeps the bit rate strictly within that of the input stream. Although the need for keeping the rate of a watermarked stream under control has been recognized for many years, most proposals have controlled the watermark embedding at the DCT level. We have analyzed the syntax change due to watermarking and show that the change is closed in the slice containing the DCT coefficient to be modified, although it could propagate beyond the block boundary, sometimes even into successive macroblocks. Based on this analysis, we developed a new embedding algorithm to adjust the bit rate of the resulting stream precisely at the end of every slice. In our experiments, about 30-60% of watermarks were successfully embedded into 6-Mbps (bit/second) video stream without any increase in bit rate compared to unrestricted embedding.
