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Tampering Detection of Video and its Selective Reconstruction in Compressed Domain

Azizian, Bardia | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50589 (09)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ghaemmaghami, Shahrokh
  7. Abstract:
  8. Availability of video recording instruments and ease of working with video editing tools have made contents of this digital signal unreliable in general. The goal of this thesis is to present a method to detect tampering of compressed videos in H.264/AVC format and restoring an approximate version of its original contents using watermarking. In the proposed scheme, a low resolution image from a number of video frames in certain time slots are embedded into the DCT coefficients of the other parts of the video which are adequately far from the reference frames. For detecting temporal and spatial tampering, the index of each frame and macroblock is embedded into itself as an authentication code. Malicious tampering is detected by observing a mismatch between the extracted and embedded codes of affected frames or macroblocks, and the original contents of suspicious areas could be restored by extracting the hidden images. The main focus of the video watermarking system designed here is on increasing its robustness. Hence, an embedding algorithm is proposed for embedding the data into the video which employs a robust property of a mid-frequency DCT level of the macroblocks’ residuals. Being zero or non-zero quantized DCT level hiding a data bit, determines the embedded bit. The experimental results show that the robustness of our system excels the most of the similar tampering detection schemes in H.264/AVC domain, despite the high payload capacity offered by our method. The average bit error rate of the watermark signal for recompression attack in the proposed scheme is about 4.5% under QP=24. The main achievement of the proposed watermarking system is the restoration of tampered areas, in addition to the high accuracy in detecting malicious tampering. To the best of our knowledge, there is no video tampering detection system implemented in H.264/AVC domain that can also restore the tampered areas
  9. Keywords:
  10. Tamper Detection ; H.264 Video Codec ; Discrete Cosine Transform ; Compressed Video Watermarking ; Video Tampering Detection ; Video Authentication ; Video Self-Recovery

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