基于光流周期特性的视频帧率上转篡改检测

视频帧率上转是视频时域篡改的一种常见篡改手段，它通过周期性地在两个视频帧中间插入中间帧的方式，实现将视频由低帧率转换到高帧率的目标.本文提出了一种基于光流周期特性的视频帧率上转篡改检测算法，首先将视频转为帧图像序列，然后采用Horn-Schunck光流法计算每帧图像每个像素点的光流矢量，并计算相邻帧图像光流的变化率.最后利用快速傅里叶变换对光流变化率数据进行频谱分析，根据最高谱线的幅值与平均幅值的比值阈值来判别视频是否经过篡改.实验表明，算法不仅能够准确识别待测视频是否经过帧率上转篡改，并且提高了视频压缩的鲁棒性能，具有一定的实际应用价值.

Detection of Video Frame-Rate Up-Conversion Using Periodic Properties of Optical Flow

Video frame-rate up-conversion is one of the common video tampering technologies in the time domain, which achieves the frame conversion of video from a low frame-rate to a higher frame-rate by periodically inserting intermediate frames between two frames in the original video. A detection algorithm based on the periodic properties of optical flow for video frame-rate up-conversion tampering is proposed in this paper. Firstly, the video is converted into images. Then the Horn-Schunck optical flow method is used to calculate the optical flow vector of each pixel in each frame, and the optical flow change rate of the adjacent frames is calculate. Finally, the fast Fourier transform is used for the spectral analysis of the optical flow change rate. And whether the inspected video is altered by frame-rate up-conversion would be determined by judging whether the ratio of the max spectrum amplitude and the mean spectrum amplitude is higher than a certain threshold. Experiment results show that the proposed algorithm not only can accurately identify the video tampered by frame-rate up-conversion, but also improve the robust performance of video compression well, and has certain practical application.