如何关闭已经打开的mci设备？

Question

打开：
m_mciOpen.lpstrElementName = filename;
m_strFileName = filename;
if(mciSendCommand(NULL,MCI_OPEN,MCI_OPEN_ELEMENT,(DWORD)&m_mciOpen))
{
return FALSE;
}
在关闭时
mciSendCommand(m_mciOpen.dwDeviceID,MCI_CLOSE,0，NULL)
总是异常。如何解决？

Answer 1

mciID = mciGetDeviceID(AVI_VIDEO);
mciSendCommand(mciID, MCI_CLOSE, 0L,
                   (DWORD)(LPMCI_GENERIC_PARMS)&mciClose);

Answer 2

DWORD CWave::OpenDevice()
{
DWORD dwResult=0;
if (m_nDeviceID)MCI_OPEN_PARMS mciOpenParms;
mciOpenParms.lpstrDeviceType=(LPSTR)MCI_DEVTYPE_WAVEFORM_AUDIO;
//open the wave device
dwResult=mciSendCommand(NULL,MCI_OPEN,
MCI_OPEN_TYPE|MCI_OPEN_TYPE_ID|MCI_WAIT,
(DWORD)(LPVOID)&mciOpenParms);
//save device identifier,will use eith other MCI commands
m_nDeviceID=mciOpenParms.wDeviceID;
//display error message if failed
if(dwResult)
DisplayErrorMsg(dwResult);
}
//return result of MCI operation
return dwResult;
}DWORD CWave::CloseDevice()
{
DWORD dwResult=0;//close if currently open
if(m_nDeviceID)
{//close the MCI device
dwResult=mciSendCommand(m_nDeviceID,MCI_CLOSE,NULL,NULL);//display error message if failed
if(dwResult)
DisplayErrorMsg(dwResult);//set identifier to close state
else
m_nDeviceID=0;
}

Answer 3

我要播放的是影视文件，没有指定设备类型，直接用Close总是异常。谁知道如何解决？

Answer 4

mciSendCommand(DeviceID,MCI_CLOSE,0,0);

Answer 5

mciSendCommand(DeviceID,MCI_CLOSE,0,0);
异常

Answer 6

DWORD  wDeviceID;//公共变量
播放：
void CMyWnd::Play(CString str)
{
if(str=="")
{
MCI_DGV_PLAY_PARMS mciPlay;
    DWORD dwFlags=0; 
    mciSendCommand(wDeviceID,MCI_PLAY,dwFlags,
   (DWORD)(LPVOID)&mciPlay);    }
else
{
       if(wDeviceID!=0)
   { 
      mciSendCommand(wDeviceID,MCI_CLOSE,NULL,NULL); 
   }
       wDeviceID=0; 
   DWORD dwReturn;  
   MCI_DGV_OPEN_PARMS mciOpen;  
   mciOpen.lpstrElementName=(LPSTR)str.GetBuffer(0);
       mciOpen.wDeviceID=0;
   mciOpen.hWndParent=CWnd::GetSafeHwnd();
   mciOpen.dwStyle=WS_CHILD; 
   dwReturn=mciSendCommand(0,MCI_OPEN,(DWORD)
  (MCI_OPEN_ELEMENT|MCI_DGV_OPEN_PARENT 
        |MCI_DGV_OPEN_WS),
  (DWORD)(LPSTR)&mciOpen); 
   wDeviceID=mciOpen.wDeviceID;
   //////////////////////////
   MCI_DGV_PUT_PARMS PutParms;
   PutParms.rc.left=0;
       PutParms.rc.top=0;
   PutParms.rc.right=ix;
   PutParms.rc.bottom=iy;
   mciSendCommand(wDeviceID,MCI_PUT,MCI_WAIT|
MCI_DGV_PUT_CLIENT|
MCI_DGV_PUT_WINDOW|MCI_DGV_RECT,
(DWORD)(LPVOID)&PutParms);
////////////////////////////////
   MCI_DGV_PLAY_PARMS mciPlay;
   DWORD dwFlags=0; 
   mciSendCommand(wDeviceID,MCI_PLAY,dwFlags,
(DWORD)(LPVOID)&mciPlay);    }
} 
void CMyWnd::Pause()
{    MCI_DGV_PAUSE_PARMS PauseParms;
mciSendCommand(wDeviceID,MCI_PAUSE,0,(DWORD)(LPVOID)
&PauseParms);
}
关闭：
void CMyWnd::Close()
{
if(wDeviceID!=0)
   { 
      mciSendCommand(wDeviceID,MCI_CLOSE,NULL,NULL); 
   }
       }