how to convert video file into .flv format and cerate thumb image of the video

ReturnVideo(this.FileUpload1.FileName.ToString());

private bool ReturnVideo(string fileName)
    {
        string html = string.Empty;
        //rename if file already exists

        int j = 0;
        string AppPath;
        string inputPath;
        string outputPath;
        string imgpath;
        AppPath = Request.PhysicalApplicationPath;
        //Get the application path
        inputPath = AppPath + "Admin\\Uploads\\Videos\\OriginalVideo";
        //Path of the original file
        outputPath = AppPath + "Admin\\Uploads\\Videos\\ConvertVideo";
        //Path of the converted file
        imgpath = AppPath + "Admin\\Uploads\\Videos\\Thumbs";
        //Path of the preview file
        string filepath = Server.MapPath("~/Admin/Uploads/Videos/OriginalVideo/" + fileName);
        while (File.Exists(filepath))
        {
            j = j + 1;
            int dotPos = fileName.LastIndexOf(".");
            string namewithoutext = fileName.Substring(0, dotPos);
            string ext = fileName.Substring(dotPos + 1);
            fileName = namewithoutext + j + "." + ext;
            filepath = Server.MapPath("~/Admin/Uploads/Videos/OriginalVideo/" + fileName);
        }
        try
        {
            this.FileUpload1.SaveAs(filepath);
        }
        catch
        {
            return false;
        }
        string outPutFile;
        outPutFile = "~/Admin/Uploads/Videos/OriginalVideo/" + fileName;
        int i = this.FileUpload1.PostedFile.ContentLength;
        System.IO.FileInfo a = new System.IO.FileInfo(Server.MapPath(outPutFile));
        while (a.Exists == false)
        {

        }
        long b = a.Length;
        while (i != b)
        {

        }

        string cmd = " -i \"" + inputPath + "\\" + fileName + "\" \"" + outputPath + "\\" + fileName.Remove(fileName.IndexOf(".")) + ".wmv" + "\"";
        ConvertNow(cmd);
        ViewState["fileName"] = fileName.Remove(fileName.IndexOf(".")) + ".wmv";
        string imgargs = " -i \"" + outputPath + "\\" + fileName.Remove(fileName.IndexOf(".")) + ".wmv" + "\" -f image2 -ss 1 -vframes 1 -s 280x200 -an \"" + imgpath + "\\" + fileName.Remove(fileName.IndexOf(".")) + ".jpg" + "\"";
        ConvertNow(imgargs);

        return true;
    }
    private void ConvertNow(string cmd)
    {
        string exepath;
        string AppPath = Request.PhysicalApplicationPath;
        //Get the application path
        exepath = AppPath + "Admin\\ffmpeg.exe";
        System.Diagnostics.Process proc = new System.Diagnostics.Process();
        proc.StartInfo.FileName = exepath;
        //Path of exe that will be executed, only for "filebuffer" it will be "wmvtool2.exe"
        proc.StartInfo.Arguments = cmd;
        //The command which will be executed
        proc.StartInfo.UseShellExecute = false;
        proc.StartInfo.CreateNoWindow = true;
        proc.StartInfo.RedirectStandardOutput = false;
        proc.Start();

        while (proc.HasExited == false)
        {
        }

    }