The MCIWNDM_SETSPEED message sets the playback speed of an MCI device. You can send this message explicitly or by using the MCIWndSetSpeed macro.
MCIWNDM_SETSPEED
wParam = 0;
lParam = (LPARAM) (UINT) iSpeed;
Returns zero if successful or an error otherwise.
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, MCIWndSetSpeed