[StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)]
        public struct NET_DVR_SHOWSTRINGINFO
        {
            //编码端字符叠加配置结构 
            public ushort dwShowString;
            public int wStringSize;
            public ushort wShowStringTopLeftX;
            public ushort wShowStringTopLeftY;
            //[MarshalAs(UnmanagedType.LPArray, SizeConst = 44)]
            //public char[] sString;

            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 44)]
            public string sString;

        }


        [StructLayout(LayoutKind.Sequential)]
        public struct NET_DVR_SHOWSTRING
        {
            //叠加字符结构
            public int dwSize;
            public NET_DVR_SHOWSTRINGINFO struStringInfo;
        }


        //编码端叠加字符
        [DllImport("HCNetSDK.dll")]
        public static extern bool NET_DVR_SetDVRConfig(int lUserID, int dwCommand, int lChannel, NET_DVR_SHOWSTRING lpInBuffer, int dwInBufferSize);


        private void button5_Click(object sender, EventArgs e)
        {
            NET_DVR_SHOWSTRINGINFO _showstringinfo = new NET_DVR_SHOWSTRINGINFO();

            NET_DVR_SHOWSTRING _showstring = new NET_DVR_SHOWSTRING();

            string strTT = "我是来测试的!";

            _showstring.dwSize = 1;
            _showstring.struStringInfo = _showstringinfo;
            _showstring.struStringInfo.dwShowString = 1;
            _showstring.struStringInfo.sString = strTT;
            _showstring.struStringInfo.wStringSize = strTT.Length;
            _showstring.struStringInfo.wShowStringTopLeftX = 100;
            _showstring.struStringInfo.wShowStringTopLeftY = 100;

            int iSize= Marshal.SizeOf(_showstring);

            bool bac = NET_DVR_SetDVRConfig(iLoginRef, 131, 0, _showstring, iSize);
            if (bac == false)
            {
                MessageBox.Show("失败");
            }
         }

/*****************************DS-6001D/F(end)***************************/

//单字符参数(子结构)
typedef struct 
{
    WORD wShowString;                // 预览的图象上是否显示字符,0-不显示,1-显示 区域大小704*576,单个字符的大小为32*32
    WORD wStringSize;                /* 该行字符的长度，不能大于44个字符 */
    WORD wShowStringTopLeftX;        /* 字符显示位置的x坐标 */
    WORD wShowStringTopLeftY;        /* 字符名称显示位置的y坐标 */
    char sString[44];                /* 要显示的字符内容 */
}NET_DVR_SHOWSTRINGINFO, *LPNET_DVR_SHOWSTRINGINFO;

//叠加字符(9000扩展)
typedef struct 
{
    DWORD dwSize;
    NET_DVR_SHOWSTRINGINFO struStringInfo[MAX_STRINGNUM_V30];                /* 要显示的字符内容 */
}NET_DVR_SHOWSTRING_V30, *LPNET_DVR_SHOWSTRING_V30;

//叠加字符扩展(8条字符)
typedef struct 
{
    DWORD dwSize;
    NET_DVR_SHOWSTRINGINFO struStringInfo[MAX_STRINGNUM_EX];                /* 要显示的字符内容 */
}NET_DVR_SHOWSTRING_EX, *LPNET_DVR_SHOWSTRING_EX;

//叠加字符
typedef struct 
{
    DWORD dwSize;
    NET_DVR_SHOWSTRINGINFO struStringInfo[MAX_STRINGNUM];                /* 要显示的字符内容 */
}NET_DVR_SHOWSTRING, *LPNET_DVR_SHOWSTRING;

/*********************************************************
  Function:    OnBnClickedBtnStringOk
  Desc:        finish text overlay settings
  Input:    
  Output:    
  Return:    
**********************************************************/
void CDlgRemoteShowString::OnBnClickedBtnStringOk()
{
    UpdateData(TRUE);
    char szLan[128] = {0};
    int i = m_comboShowArea.GetCurSel();
    m_struShowString.struStringInfo[i].wShowString = (WORD)m_bChkShow;
    memcpy(m_struShowString.struStringInfo[i].sString, m_csString, 44);
    m_struShowString.struStringInfo[i].wStringSize = (WORD)strlen(m_csString);
    m_struShowString.struStringInfo[i].wShowStringTopLeftX = (WORD)m_iStringX;
    m_struShowString.struStringInfo[i].wShowStringTopLeftY = (WORD)m_iStringY;    
    if (!NET_DVR_SetDVRConfig(m_lLoginID, NET_DVR_SET_SHOWSTRING_V30, m_iChanShowNum, &m_struShowString, sizeof