A robust watermarking scheme against re-compression attack for H.265/HEVC

In this paper, a compressed domain blind watermarking scheme is proposed which embeds the watermark by altering the number of nonzero transform co-efficients (NNZ) of 4 × 4 transform blocks of the HEVC video sequence. To embed the watermark, firstly, temporally homogeneous blocks having relatively less motion are selected. In this work, watermark is inserted in the Intra (I) frame and the motion characteristics of the I frame has been determined using the motion information of the Inter (P or B) predicted frames of its close neighborhood. The watermark is embedded by altering the NNZ difference of 4 × 4 transform blocks in the consecutive intra predicted frames. A comprehensive set of experiments is carried out to show that the scheme is robust against re-compression attacks while maintaining a descent visual quality (PSNR), the bit increase rate (BIR) of the watermarked video.