Combined and Calibrated Features for Steganalysis of Motion Vector-Based Steganography in H.264/AVC

This paper presents a novel feature set for steganalysis of motion vector-based steganography in H.264/AVC. First, the influence of steganographic embedding on the sum of absolute difference (SAD) and the motion vector difference (MVD) is analyzed, and then the statistical characteristics of these two aspects are combined to design features. In terms of SAD, the macroblock partition modes are used to measure the quantization distortion, and by using the optimality of SAD in neighborhood, the partition based neighborhood optimal probability features are extracted. In terms of MVD, it has been proved that MVD is better in feature construction than neighboring motion vector difference (NMVD) which has been widely used by traditional steganalyzers, and thus the inter and intra co-occurrence features are constructed based on the distribution of two components of neighboring MVDs and the distribution of two components of the same MVD. Finally, the combined features are enhanced by window optimal calibration, which utilizes the optimality of both SAD and MVD in a local window area. Experiments on various conditions demonstrate that the proposed scheme generally achieves a more accurate detection than current methods especially for videos encoded in variable block size and high quantization parameter values, and exhibits strong universality in applications.