Compressed-domain video watermarking for H.264

This paper presents a novel, low complexity watermarking algorithm for H.264 that exploits the specific features of this new standard. The security of the algorithm is based on the randomness of the watermark location. The coefficient with the embedded watermark within the macroblock is determined by a public key extracted from the macroblock and a secret key possessed by the copyright owner. It is proposed to use the relative change of the DC coefficients of the 4×4 blocks in a macroblock to generate the public key. The watermark is embedded in the quantized AC coefficients of I frames, and the compressed video bit rate is only increased 0.5% on average. Watermark detection can be done without the original video signal, and the algorithm is appropriate for real-time applications. Simulation results show that watermark embedding preserves the perceptual quality of the video. However, the degradation induced by an adversary´s attempt to remove the watermark creates visible artifacts.