Research On Reversible Video Data Hiding Based On H.264/avc Standard

With the rapid development of computer and network technology, digital multimedia information has gradually replaced the traditional media. They are stored on computer and tranmitted through network, bringing great convenience to people's life. However, at the same time, this technology gives birth to some new problems, such as how to authenticate the copyright, how to prevent the unauthorized access and tampering, and so on.Information hiding is an effective method dealing with this problem. It protects the secret information by hiding it in an inperceptible manner into some overt media which is stored and transmitted openly. Reversible data hiding is a novel branch of data hiding technology. The original information of the host could be accurately restored after extracting the secret information embedded within. The reversibility is essential to some sensitive applications such as medical diagnosis and law enforcement, which requires high fidelity and can't tolerate even the slightest distortion. H.264/AVC is a brand new video coding standard, and the most frequently utilized standard in reality as well. In view of the conprehensive application of this standard, the data hiding technology based on this kind of video is of special meaning and is attracting more and more eyesight attention among the researchers.Based on the analysis of H.264/AVC video encoding standard and some relevent research fruits in the data hiding field, this thesis is engaged in the research of reversible information hiding technology, and presents two algorithms for H.264 videos.1. A novel reversible data hiding algorithm used in H.264 videos. In this part, the generalized difference expansion algorithm in image data hiding field is employed and modified to adapt to the application in H.264 videos. This algorithm embeds information in the quantized DCT coefficients to ensure the reversibility of the method. An adaptive embedding position selection policy is presented to relieve the degration of visual quality produced by the embedding process. The experiment results show that a good data capacity is accheived while keeping the visual quality acceptible.2. A novel reversible bi-level drift compenstion algorithm. In light of the distortion drift problem occuring after the embedding process, we propose a reversible drift compensation method which is based on the features of the inner frame prediction machanism of H.264. This method compensates the I4 and I16 microblocks with two different kind of compenstion algorithm, respectively. Experiment results show that the proposed method effectively restrains the distortion caused after data embedding.The scheme employing both of the two algorithms above jointly can acheive very high data capacity as well as good inperceptibilty. Besides, since the two algorithms are both reversible, the whole scheme also boasts reversibility which ensures that the original video content could be accurately restored after the extracting process.