The authors of this article discuss digital video forensics, specifically, digital tampering, double MPEG-2 compression, and quantization, and demonstrate the practical value of their proposed algorithm.
Detection of double compression in digital multimedia is considered to reveal the history of multimedia signal processing, which is very useful in digital forensics. In this paper, distributions of quantized DCT coefficients are analyzed in depth after double MPEG-2 compression with constant bit rate (CBR) mode, and a new algorithm is presented to detect double MPEG-2 compression based on convex patterns in the distribution of quantized DCT coefficients. In order to demonstrate the practical value of the authors’ proposed algorithm, two digital video cameras (DV) and two MPEG-2 software coders are utilized to simulate the general process of double MPEG-2 compression. Experiment results show that the proposed scheme can effectively detect doubly MPEG-2 compressed videos with CBR mode and the target output bit rate can vary in a large range.(Published Abstract Provided)