A DWT-based object watermarking system for MPEG-4 video streams

The MPEG-4 standard is revealing very attractive for a large set of applications. In some of them a copy protection system allowing to control the distribution of multimedia data is required. A new technology useful for copyright protection is watermarking: a digital code (watermark), indicating the copyright owner, is directly embedded into the video signal. The possibility of the MPEG-4 standard to directly access objects within a video sequence introduces a constraint to the watermarking process: even if a video object is transferred from a sequence to another, the copyright data of the single object has to be correctly detected. Another requirement is that, in order to be robust against format conversions, the watermark has to be inserted before compression. The method proposed in this paper satisfies the previous requirements by relying on an image watermarking algorithm which embeds the code in the discrete wavelet transform of each frame.