Lossless data-hiding for H.264/AVC videos

A lossless data-hiding scheme for the H.264/AVC compressed bit-stream is presented in this paper. Traditional data-hiding schemes of compressed videos would incur a great deal of permanent degradation of signal quality distortion in the marked bit-stream. In the paper, the proposed video data-hiding scheme is able to restore exactly the originally encoded video signal at the decoder while extracting the hidden secret message bits from the marked bit-stream. The embedding algorithm that is developed uses prediction of transform coefficients between neighboring 4×4-blocks in a macroblock and reversible histogram-shifting of the values of prediction-error to embed secret message bits in the non-zero quantized transform coefficients (NZQCs). Only a few of NZQCs in a macroblock are selected and modified with concerns of suppressing variations of bit-rate and visual quality from the marked bit-stream. Experimental results show that the message bits can be hidden in the encode bit-stream at the expense of a slight bit-rate increase and the original quality of encoded video can be rendered by the decoder after extracting the hidden bits.