Study On H.264/AVC Video Information Hiding And Detecting Technology

People often use cryptography system to encrypt the message before the transmission, for ensuring the confidentiality of the information. But the encrypted cipher text is disorganized, and distinct from the ordinary plain text message. So the transmission will be identifiable, and spectacular. Secret information will be directly exposed to the attacker. However, information hiding technology hides the existence of secret information, so the attacker will not realize that the information being transferred, and then ensure the confidentiality of message delivery.Information hiding technology takes advantages of information redundancy and human perception redundancy of the carrier, so video is a natural good carrier because of its great information redundancy and human perception redundancy. H.264/AVC video coding standard has been widely used as the most common form of network video transmission, because of the high compression efficiency and the excellent network adaptability. Therefore, the combination of H.264/AVC video and information hiding and detection technology has become one of the hot areas of information hiding.This paper has done researches of the information hiding and detection based on H.264/AVC video compression domain. The main works as follows:A video steganalysis algorithm is proposed in this paper, which is used to detect the hidden information via modulating H.264/AVC intra-prediction mode. Based on the conclusion that as to the image’s quantized differential DCT coefficient, the difference between the reconstructed signal and the original one has zero mean, it’s found that the non-optimal intra-prediction mode which was modulated for covert communication will be converted to the natural optimum intra-prediction mode. Then the steganalysis scheme is proposed based on the transition probability matrix. Experimental results demonstrate that the algorithm is very effective in detecting hiding-data, moreover the embedding rate is very low.On the basis of in-depth study of H.264/AVC, a video steganography algorithm is proposed in the paper utilizing motion vector of the inter prediction. The H.264/AVC coders divide the macroblock into small partitions when coding the P frames for researching the optimal motion vector. This paper takes advantages of the correlation between motion vectors of neighboring macroblock partition. This paper use the difference expansion technique to expand the difference of the neighboring macroblock motion vectors, then embedded the secret information in the LSB of the difference expanded. Because of the re-encoding of current coding macroblock based on the new motion vectors, the embedding process is equivalent to choosing a non-optimal motion vectors in the coding process. So the algorithm maintains the objective and subjective video quality well, only increases the video rate. And secret information embedding and extraction process is very rapid.