Cover Block Decoupling for Content-Adaptive H.264 Steganography

This paper makes the first attempt to achieve content-adaptive H.264 steganography with the quantised discrete cosine transform (QDCT) coefficients in intra-frames. Currently, state-of-the-art JPEG steganographic schemes embed their payload while minimizing a heuristically defined distortion. However, porting this concept to schemes of compressed videos remains an unsolved challenge. Because of H.264 intra prediction, the QDCT coefficient blocks are highly depended on their adjacent encoded blocks, and modifying one coefficient block will set off a chain reaction in the following cover blocks. Based on a thorough investigation into this problem, we propose two embedding strategies for cover block decoupling to inhibit the embedding interactions. With this methodology, the latest achievements in the JPEG domain are expected to be incorporated to construct H.264 steganographic schemes for better performances.