#region 从视频画面中截取一帧画面为图片
        /// <summary>
        /// 从视频画面中截取一帧画面为图片
        /// </summary>
        /// <param name="VideoName">视频文件，绝对路径</param>
        /// <param name="WidthAndHeight">图片的尺寸如:240*180</param>
        /// <param name="CutTimeFrame">开始截取的时间如:"1"</param>
        /// <returns></returns>
        public string GetPicFromVideo(string VideoName, string WidthAndHeight, string CutTimeFrame)
        {
            string ffmpeg = Server.MapPath("/") + "ffmpeg.exe";//ffmpeg执行文件的路径
            string PicName = VideoName + ".jpg";//视频图片的名字，绝对路径
            System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo(ffmpeg);
            startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
            startInfo.Arguments = " -i " + VideoName
                                + " -y -f image2 -ss " + CutTimeFrame
                                + " -t 0.001 -s " + WidthAndHeight
                                + " " + PicName;  //設定程式執行參數
            try
            {
                System.Diagnostics.Process.Start(startInfo);
                Thread.Sleep(5000);//线程挂起，等待ffmpeg截图完毕
            }
            catch (Exception)
            {
                return "";
            }

            //返回视频图片完整路径
            if (System.IO.File.Exists(PicName))
                return PicName;
            return "";
        }
        #endregion