Detection of double compression with the same bit rate in MPEG-2 videos

The detection of double compression with the same bit rate in MPEG-2 is of great significance in the field of video forensics. However, when the singly compressed and the doubly compressed videos have the same bit rate, no detecting method has been reported yet. In this paper, we propose a new method that can detect double MPEG-2 compression with the same bit rate. Our method is based on the observation that the number of different coefficients between I frames of the singly and doubly compressed MPEG-2 videos is much larger than the number of different coefficients between the I frames of the corresponding doubly and triply compressed MPEG-2 videos. Via a new re-compressing strategy, the aforementioned characteristics of MPEG-2 video can be utilized to discriminate the singly compressed and doubly compressed MPEG-2 videos. Various experiments on different bit rates demonstrate the efficiency of our new method.