The recent finalization of MPEG-4 will make this standard very attractive for a large range of applications such as video editing, Internet video distribution, wireless video communications. Some of these applications are likely to get great benefit from watermarking technology, since it can enable a number of innovative services, such as conditional access policies, data annotation, data labeling, content authentication, to be implemented at a low price. One of the key points of the MPEG-4 standard is the possibility to access and manipulate objects within a video sequence. Thus object watermarking has to be achieved in such a way that, while a video object is transferred from a sequence to another, it is still possible to correctly access the data embedded within the object itself. The algorithm proposed in this paper embeds a watermark in each video object by imposing a particular relationship between some predefined pairs of quantized discrete cosine transform (DCT) coefficients in the luminance blocks of pseudo-randomly selected macroblocks (MBs). Watermarks are equally embedded into intra and inter MBs. Experimental results are presented validating the effectiveness of the proposed approach.

Digital watermarking involves embedding copyright marks (watermarks), often imperceptibly, in multimedia objects to enhance or protect their value. In this paper we describe a novel watermarking algorithm suitable for video coding techniques such as MPEG-4 and H.263/H.324 and we test it in a wireless environment. The proposed algorithm satisfies critical properties not all of which are available in previous solutions. These properties include: resistance (robustness) of the embedded watermark to the error-prone nature of wireless channels as well as to video frame loss or misplacement, negligible probability of reading a non-embedded watermark, non-degradation of the marked video sequence and the possibility to mark video objects (e.g., MPEG-4 objects) in a single frame separately. Experimental results are given that show how these and other properties are achieved when video sequences are corrupted with errors that are typical of a wireless channel.