Abstract: An improved information hiding algorithm based on H.264’s specific motion estimation with quarter-pixel precision was proposed.By modifying every sub-block’s best matching position of macroblock and using the mapping rule between sub-block’s position and binary information,the information is embedded in sub-block’s position.Information extraction based on the interpolation process of luma pixels in decoder of H.264 doesn’t need the original videos and belongs to the blind extraction mechanism.The experiment results demonstrate that the improved information hi-ding algorithm in motion estimation of H.264 increases the hiding capacity and decreases the system cost without decreasing the video quality conspicuously,which has higher integer performance than other algorithms.

Key words: Information hiding,H.264,Motion estimation,Quarter-pixel