| Summary: | 碩士 === 國立東華大學 === 資訊工程學系 === 98 === In recent years, there has been a dramatic increase in the number of researches on audio/video compression technologies and computer network, and many productions of digital multimedia emerge on the network. The need of information hiding into digital multimedia attracted a great deal of interest for security and secret communication. Information hiding is a technique to hide secret messages into certain video sequence imperceptibly. The transmission of secret information in video conference is one of such applications.
H.264/AVC is the state-of-the-art video standard with higher compression efficiency and the effect of coding is better than others. Therefore, H.264/AVC is expected to be one of the most popular video coding standards for wireless channels and Internet media.
In this thesis, we propose a novel information hiding technique in H.264/AVC. The first procedure is the block selection which selects the appropriate 4x4 block in each macro-block of I frames. After that, an information bit is embedded by adaptively modifying the number of nonzero quantized AC coefficients in each macro-block of I frames. The perceptual quality in the block is not influenced drastically by the existence of modified coefficient. The proposed technique can constrain the perceptual degradation and bit rate increasing, which are caused by embedding the information bits. Besides, the complexity of the technique is lower and it can be implemented simply in the encoder. Simulation results show that the proposed scheme is appropriate to be adopted by real-time video applications.
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