Key Technology Of Reversible Cloud Surveillance Video Privacy Protection

Cloud-based video surveillance system has a brilliant prospect in application. In the surveillance system, there is a risk of data leakage. As surveillance videos often contain privacy information, this would lead to the leakage of privacy information. So it is necessary to encrypt surveillance videos. In addition, surveillance videos are often used as evidence in judicial procedure. Thus the encryption of videos should be reversible and the integrity of videos should be kept. Finally, in order to meet real-time requirement, the overhead brought by encryption should be small. As traditional encryption methods cannot meet the requirement, a new solution should be brought up.Reversible cloud video surveillance privacy, only encrypt the region of interest, while the content of other areas remain unchanged. And the encryption is format compliant, the encrypted video could be played even without decryption. The encryption is reversible, this makes the authorized users could recover the original file after decryption. The solution is based on the widely used coding standard of H.264. First of all, the quantized DCT coefficients(Quantized DCT Coefficients, QDCT) and intra prediction mode difference(Intra-frame Prediction Modes Difference, IPMD) in privacy region are encrypted. Then process the non-private areas that referred the intra prediction mode of blocks in privacy region. Use information that after encryption to update these part and re-encoding. Finally, remove the error drift by compensation for the blocks in non-private region that influenced by the encryption of QDCT in privacy region.The test results show that non-destructive privacy protection program makes the privacy zone unrecognized visually and the non-privacy region remain unchanged. What is more, it could the requirements such as abnormal behavior detection. The encryption is reversible and original video sequence could be recovered. And extra space overhead generated by encryption is less than 6%, which is substantially.