ffmpeg视频水印

/// <summary>
        /// ffmpeg视频水印
        /// </summary>
        /// <param name="inputPath"></param>
        /// <param name="pathName"></param>
        /// <returns></returns>
        public string WaterMark(string inputPath, string pathName)
        {
            Process p = new Process();
            p.StartInfo.FileName = "PowerShell.exe";
            p.StartInfo.UseShellExecute = false;
            p.StartInfo.RedirectStandardInput = true;
            p.StartInfo.RedirectStandardOutput = true;
            p.StartInfo.Verb = "runas";
            p.StartInfo.CreateNoWindow = false;
            p.Start();
            p.StandardInput.WriteLine(@"[console]::outputencoding=[system.text.encoding]::utf8");
            p.StandardInput.WriteLine(@" d: ; cd ffmpeg/bin ; ffmpeg.exe -y -i " + inputPath + @" -acodec copy -b:v 300k -vf  'movie=logo.png,scale=200:40 [watermark]; [in][watermark] overlay=main_w-overlay_w-10:10 [out] ' " + Server.MapPath("~/Content/UpFiles/HouseVideo/SY") + pathName);
            p.StandardInput.AutoFlush = true;
            p.StandardInput.WriteLine("exit");
            p.Close();
            return Server.MapPath("~/Content/UpFiles/HouseVideo/SY") + pathName;
        }