Fraunhofer Institut für Integrierte Publikations-und Informationssysteme IPSI

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  • Publication
    Synchronization techniques to detect MPEG video frames for watermark retrieval
    ( 2004)
    Hauer, E.
    ;
    Thiemert, S.
    A main problem of I-frame based watermarking schemes is their lack of robustness regarding re-encoding attacks on MPEG material. After a normal post-processing modification the structure of the Groups of Pictures (GOPs) in the modified video should be the same as in the original one. An attack, which has the goal to destroy the watermark, could change this structure. The position of the marked intra coded frames will be shifted. Without detecting the correct frame position an incorrect watermark message could be retrieved. Our conceptual paper proposes a possible solution. A combined watermark, consisting of two watermark messages, is embedded into the video material to increase the robustness of the watermark. The first part of the message is the synchronization information to locate the previously marked frames. The second part contains the information watermark. Our approach is to design a template pattern based on the synchronization information. With the pattern th e original I-frame can be detected and the correct watermark information can be retrieved. After the recovery of the attacked video material the watermark can be correctly retrieved. We present the concept and the evaluation of the first test results.
  • Publication
    Authentication of MPEG-4 data: Risks and solutions
    ( 2003)
    Lang, A.
    ;
    Thiemert, S.
    ;
    Hauer, E.
    ;
    Liu, H.
    ;
    Petitcolas, F.A.P.
    MPEG-4 is an international object-based standard that provides technological basis for digital television, interactive graphics and multimedia applications. These objects can be natural or synthetic e.g. textures, 3D objects, videos or sounds. In this paper we suggest an integrity approach to protect the content of MPEG-4 data. The essential part of this approach is to embed a robust watermark into each visual, audio and 3D object. The content fragile watermark verifying the integrity of a scene is the sum of all information retrieved from the robust watermarks extracted from the objects of the scene. The information of the fragile watermark will be distributed redundantly to all robust watermarks of the scene. Another essential part of our approach is to embed a part of the scene description or object descriptors as a watermark message into the video or audio streams. The amount of embedded information depends on the payload of the watermarking algorithms. We also anal yze the possibility of embedding equivalent information into 3D models, depending on the application.