A Video Steganalytic Approach Against Quantized Transform Coefficient-Based H.264 Steganography by Exploiting In-Loop Deblocking Filtering

This article presents a method for detection of H.264 steganographic algorithms that modulate quantized transform coefficients (QTCs) for data hiding. The in-loop deblocking filter specified in the H.264 standard is used for attenuating the discontinuities at coded block boundaries. However, our investigation indicates that the deblocking filtering process would probably be affected by QTC modification. Therefore, we suggest performing steganalysis by considering the influence of QTC modification on filtering decisions and filtering operations. In the filtering of luma block edges, for each luma sample, we try to obtain the cumulative amount of modification applied to it caused by filtering operations, and determine the frequency of the modification made to its sample value. Based on this, a 768-dimensional feature set is designed for training and classification. Extensive experiments were conducted under a range of setups to evaluate the effectiveness of the proposed method. The corresponding experimental results demonstrate that, compared with the prior art, our proposed method is generally capable of providing superior performance on detecting QTC modification in H.264 video, even at low embedding strengths.