/// <summary>
        /// 将Wav音频转成pcm手机音频
        /// </summary>
        /// <param name="applicationPath">ffmeg.exe文件路径</param>
        /// <param name="fileName">WAV文件的路径(带文件名)</param>
        /// <param name="targetFilName">生成目前amr文件路径（带文件名）</param>
        public void ConvertToPcm(string applicationPath, string fileName, string targetFilName)
        {
            string c = applicationPath + @"\\ffmpeg.exe -y -i " + fileName + " -acodec pcm_s16le -f s16le -ac 1 -ar 16000 " + targetFilName;
            var res = Cmd(c);
        }

        /// <summary>
        /// 执行Cmd命令
        /// </summary>
        private string Cmd(string c)
        {
            string strOuput = string.Empty;
            try
            {
                Process p = new Process();
                //设置要启动的应用程序
                p.StartInfo.FileName = "cmd.exe";
                //是否使用操作系统shell启动
                p.StartInfo.UseShellExecute = false;
                // 接受来自调用程序的输入信息
                p.StartInfo.RedirectStandardInput = true;
                //输出信息
                p.StartInfo.RedirectStandardOutput = true;
                // 输出错误
                p.StartInfo.RedirectStandardError = true;
                //不显示程序窗口
                p.StartInfo.CreateNoWindow = true;
                //启动程序
                p.Start();

                //向cmd窗口发送输入信息
                p.StandardInput.WriteLine(c + "&exit");

                p.StandardInput.AutoFlush = true;

                //获取输出信息
                strOuput = p.StandardOutput.ReadToEnd();
                //等待程序执行完退出进程
                p.WaitForExit();
                p.Close();
            }
            catch
            { }
            return strOuput;
        }

            var appid = "xxx";//讯飞申请的appid
            var apikey = "xxxxxxxxxxxxxxxxxxxxx";

            var data = File.ReadAllBytes(path);//path为转化后的pcm文件路径

            string base64_audio = Convert.ToBase64String(data);//将二进制的语音文件转base64

            string body = "audio=" + System.Web.HttpUtility.UrlEncode(base64_audio);

            string url = "http://api.xfyun.cn/v1/service/v1/iat";

            string X_Param = ToBase64String("{ \"engine_type\": \"sms16k\", \"aue\": \"raw\"}");//转base64，注意要保去除空格，因为讯飞后台有去空格操作

            string X_Time = GetTimeStamp(true);//获取时间戳

            HttpContent httpContent = new StringContent(body, Encoding.UTF8, "application/x-www-form-urlencoded");

            httpContent.Headers.Add("X-Param", X_Param);

            httpContent.Headers.Add("X-CurTime", X_Time);

            httpContent.Headers.Add("X-Appid", appid);

            httpContent.Headers.Add("X-CheckSum", MD5String(apikey, X_Time, X_Param));

            var httpClient = new HttpClient();

            HttpResponseMessage response = httpClient.PostAsync(url, httpContent).Result;

            var content = "对不起，识别不出来...";
            if (response.IsSuccessStatusCode)

            {
                var responseJson = JsonHelper.Deserialize<XfResponse>(response.Content.ReadAsStringAsync().Result);
                if (responseJson.code == "0")
                {
                    content = responseJson.data;
                }
                else
                {
                    content = responseJson.code;
                }
            }