REAL TIME DIGITAL VIDEO WATERMARKING FOR DIGITAL RIGHTS MANAGEMENT VIA MODIFICATION OF VLCS

Digital watermarking is a data hiding technology that can be used for digital rights management. It embeds an invisible signal including owner identification and copy control information into multimedia data for copyright protection against illegal copying and distribution. In this paper, we embed the watermark in I-pictures of the MPEG video sequence by modifying VLCs (variable length codes) directly to avoid inverse DCT (discrete cosine transform) and inverse quantization. The modification of VLCs is intended to minimize the perceptual degradation of video quality caused by the embedded watermark. Because we select VLCs with the same run value and code word length to be modified, the compressed video stream does not increase in size. Furthermore, our proposed watermarking scheme protects the embedded information by means of a secret key and a PRNG (pseudo random number generator) to generate a random binary sequence for watermarking. We apply three MPEG-1 video sequences to test our proposed algorithm. Since the watermark can be extracted by simple table lookup without using original video sequences, the computational overhead is very small. Therefore, the decoding of the watermarked video sequence can be real time for viewing. The proposed algorithm can be easily applied to MPEG-2 and MPEG-4 videos also for digital rights management