Time-Variant Watermarks for Digital Videos: An MPEG-Based Approach

Abstract

Watermarks provide a means of embedding information into digital videos that can be used for a variety of purposes, such as establishing ownership, tracing origin of copies, and so forth. We outline an approach that permits a significant increase in the amount of information that can be accommodated in a watermark, namely time-variant watermarks. The approach is formulated assuming the video is represented in an MPEG format. Implementation issues of time-variant watermarks are discussed, as are their advantages over the usual time-invariant watermarks, with emphasis on defeating attacks using filtering, cropping, resizing, and other standard methods used to defeat watermarks, such as changing existing frames, as well as new attacks, such as removing, repeating, or permuting frames.