//托管内存中的数据 复制到非托管内存中
            IntPtr ptrURL = Marshal.StringToHGlobalAnsi("123465");
            //释放在非托管中分配的内存
            Marshal.FreeHGlobal(ptrURL);

            NET_DVR_StartRemoteConfig(0,0,
                ptrURL, //字符串在内存中的地址
                "123465".Length,//长度
                callback //回调函数
                ,IntPtr.Zero
                );

        }


        // 调用API
        /*
         函数原型
         LONG NET_DVR_StartRemoteConfig(  
         LONG    lUserID,                              //  int
         DWORD   dwCommand,                            //  uint
         LPVOID  lpInBuffer,                           //  IntPtr
         DWORD   dwInBufferLen,                        //  Int32
         fRemoteConfigCallback    cbStateCallback,     //  RemoteConfigCallback
         LPVOID  pUserData                             //  IntPtr
         );
         callback 原型
         该原型 与委托的关联
         public delegate void RemoteConfigCallback(uint dwType, IntPtr lpBuffer, uint dwBufLen, IntPtr pUserData);

         //声明函数类型 ???
         typedef void(CALLBACK *fRemoteConfigCallback)(  
         DWORD     dwType,
         void      *lpBuffer,  
         DWORD     dwBufLen,  
         void      *pUserData
         );
         */
        [DllImportAttribute(@"HCNetSDK.dll")]
        public static extern int NET_DVR_StartRemoteConfig(
            int lUserID,
            uint dwCommand, 
            IntPtr lpInBuffer, 
            Int32 dwInBufferLen,
            RemoteConfigCallback cbStateCallback,
            IntPtr pUserData
            );

  //从非托管内存中读取一个32位带符号的整数
            uint dwStatus = (uint)Marshal.ReadInt32(ptrURL);


            //解析包数据

            ptrURL = Marshal.StringToHGlobalAnsi("123465");
            /*
              1B = 8bit  ==1byte
              1KB=1024B
              1MB=1024KB
               */
            byte[] bUserInfoSearch = new byte[1024 * 10];  //10kb大小
            //将数据从非 托管内存指针 复制到托管数组中
            Marshal.Copy(
                ptrURL,//指针地址
                bUserInfoSearch,  //数组
                0, // 开始索引
                bUserInfoSearch.Length  //长度
                );
            //以utf8编码读取数组
            string strUserInfoSearch = System.Text.Encoding.UTF8.GetString(bUserInfoSearch);