Exposing fake bitrate video and its original bitrate

Video bitrate, as one of the important factors that reflect the video quality, can be easily manipulated via some video editing softwares. In some forensic scenarios, for example, video uploaders of video-sharing websites may increase video bitrate for seeking more commercial profits. In this paper, we try to detect those fake high bitrate videos, and then further to estimate their original bitrates. The proposed method is mainly based on the fact that if the video bitrate has been increased with the help of video editing software, its essential video quality will not increase at all. By analyzing the quality of the questionable video and a series of its re-encoded versions with different lower bitrates, we can obtain a feature curve to measure the change of the video quality, and then we propose a compact feature vector (3-D) to expose fake bitrate videos and their original bitrates. The experimental results evaluated on both CIF and QCIF raw sequences have shown the effectiveness of the proposed method.