Research On Crucial Technologies Of H.264/AVC Video Integrity Authentication

In recent years, digital signal processing technology and broadband network infrastructure havedeveloped rapidly, which makes the manufacture and distribution of digital content more and moreconvenient. In the past only the professionals could edit the multimedia files, the work that can beaccomplished easily by some cheap or even free software and hardware nowadays. The change ofsituation brings convenience and benefits to most of the content users undoubtedly, however, somepotential problems come into being. First of all, a new issue is to exert: how to carry out copyrightprotection for digital multimedia contents (eg, digital music, movies and books) without affectinglegitimate users' normal operation? Secondly, concerning the content authentication, the authenticityof multimedia data will be questioned due to its easily editing feature, especially when those data areused as sworn evidence in court. In addition, many surveillance cameras are installed in publicplaces to protect the civil property. In order to facilitate storage and transmission, digital videoformat is applied in more and more surveillance cameras. Visual data of guaranteed authenticity insurveillance system, with which digital video can be served as reliable and valid evidence, which isvery important. Therefore, research on robust coding transmission, efficient video authentication andtamper recover mechanism becomes a hot issue in the field of information security.In response to problems mentioned above, this paper based on the H.264/AVC coding standard,mainly focus on designing an efficient, robust and adjustable watermark capacity authenticationalgorithm on the combination of time and coding characters of video sequences. The algorithmminimizes the influence on the parameter indicators such as bit-length and bit-rate in the H.264coding process. At the same time, researches on the tamper detection mechanism and tamperrecovery mechanism form a set of video authentication system. The main achievements are listed asfollows.First of all, a novel robust watermarking algorithm is proposed, based on the quantized layeredcoefficients of the residual macroblock and the motion vectors in the "crossing region".Visual quality is the most intuitive standard measurement of watermarking algorithmperformance. In order to improve the visual quality of watermarking algorithm, image complexityanalysis is always necessary. Compared with the image watermarking algorithm, videowatermarking algorithm in the coding and transmission includes the information of time dimension,namely a large number of inter-frame information. Simple analysis of image complexity no longerapplies to video watermarking. The study emphasizes on the video complexity analysis composed ofbrightness, texture, spatial information, and embedding watermarking by modulating the quantized layered coefficients of intra residual macroblock and motion vectors in the "crossing region" of theinter-frame macroblock. The algorithm effectively alleviates the conflict between video quality androbustness of video watermarking algorithm.Secondly, the H.264video information hiding algorithm with adjustable watermarking capacityis proposed, based on spare space formed by zero-value DCT coefficients and inter prediction mode,.Watermarking capacity is another standard measurement of watermarking algorithmperformance. To the traditional algorithm, expanding the quantity of watermark embedded willdegrade the visual quality. Thus the key issue of watermarking algorithm lies in the trade-offbetween watermark capacity and video quality. The further research launches in this area. During theintra-frame coding, quantized zero-value DCT coefficients of residual marcoblock are utilized toform a spare space, information hiding is achieved by modifying one zero-value DCT coefficients ofspare space. In the course of inter-prediction, we introduce the concept of information variablelength group and achieve information hiding by using no difference compensation characteristics ofthe H.264inter-frame variable length coding. These two courses are composed to form H.264videoinformation hiding algorithm with adjustable watermarking capacity, improving the conflict betweenwatermarking capacity and visual quality of video watermarking algorithm.Thirdly, H.264active object recognition is proposed based on digital watermarking.Intelligent video surveillance system includes the study on moving object segmentation, objectrecognition, object tracking and so on. Among these, based on the results of object segmentation,object recognition is the main content of intelligent video surveillance system, which extracts theinvariant features of each object, making a mark to draw each one's trajectory. In this dissertation,we proposed the concept of active object recognition based on digital watermarking. On the H.264coding standard, we detect the moving objects and segment them. Then we embed differentwatermarks in different objects in the reconstructed frame, which is used as the reference frame forprediction in next frame, thus, the watermarks are transmitted to the next frame. Object recognitionis realized by extracting the watermarks from the objects in the reference frame of the next frame,and embedding the watermarks in objects in the reconstructed image of the next frame, doing thisprocess circularly until completing the whole moving object identification.Finally, H.264/AVC video integrity authentication system is proposed and the research ontamper recovery mechanism is carried.Video integrity authentication system includes the processes of authentication code extraction,identification information embedding, tamper detection and localization. Video is more complicatedthan image, so that the image hash extraction method is not suitable to extract video authenticationcode. The analysis method of spatial energy fluctuation is proposed, aiming to improve the SQ orVQ quantitative methods to extract the video authentication codes effectively from video frames with different characteristics. Then we constitute H.264video integrity authentication system whichconsists of improved robust watermarking algorithm and information hiding algorithm with largecapacity aforementioned. At last, the research carried on tamper recovery mechanism to recover thetamper area in a certain degree.