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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 44584 (19)
- University: Sharif University of Technology
- Department: Computer Engineering
- Advisor(s): Ghanbari, Mohammad
- Abstract:
- Nowadays with development of applications that stream video over internet, compression efficiency of video has become very important. On the other hand, Watermarking and video coding are two conflicting technologies. One adds redundancy and other tries to remove it. We have proposed a H.264 watermarking method that does not increases the bit rate. Unlike most of watermarking schemes, this methods embeds the watermark in inter coded frames. Abundance of these frames in video is impressively more than intra frames, so a lot of capacityis eventuated. But these frames are highly compressed using motion compensation, and are very sparse. To avoid from bit rate increment, this method only embeds the watermark in non-zero coefficients. This method uses the process of variable length coding to predict the bit of coefficient after watermarking and controls the bit rate. It embeds watermark in 4x4 blocks and uses VLC lookup tables to decide to choose which coefficient should be changed.Because of embedding in non-zero coefficients of residual signal, watermark is inserted in moved and textured areas and is not perceptible for human visual system. This method is very useful for applications that need to send some information with the video sequence. This application are usually used to improve coding efficiency. Some of these aplications are, sending error correction bits in video frames to locate the possible error, sending a low resolution version of each frame in itself, for error concealment at decoder or sending headers and overhead informations in coding with the coded video, i.e. watermarking motion vectors in coded residual of each frame. It can also be used in fragile watermarking and authentication
- Keywords:
- Data Embedding in Video ; Variable Length Coding ; Interframe Coding ; Authentication
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