The MCIWNDM_GETDEVICEID message retrieves the identifier of the currently open MCI device to use with the mciSendCommand function. You can send this message explicitly or by using the MCIWndGetDeviceID macro.
MCIWNDM_GETDEVICEID
wParam = 0;
lParam = 0;
Returns the device identifier.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in vfw.h.
MCIWnd Window Class Overview, MCIWnd Messages, mciSendCommand, MCIWndGetDeviceID