The MOM_POSITION message is sent to a window when a MEVT_F_CALLBACK event is reached in the MIDI output stream.
MOM_POSITIONCB dwParam1 = (DWORD) hOutput dwParam2 = (DWORD) lpMidiHdr
Handle to the MIDI output device.
Pointer to a MIDIHDR structure that identifies the event that caused the callback function. The dwOffset member gives the offset of the event.
This message does not return a value.
Playback of the stream buffer continues even while the callback function is executing. Any events after the MEVT_F_CALLBACK event in the buffer will be scheduled and sent on time regardless of how much time is spent in the callback function.
If position callbacks are being generated more quickly than your application can process them, the dwOffset member of the MIDIHDR structure might refer to an event your application has not yet processed.
** Windows NT/2000/XP:** Included in Windows NT 3.1 and later.
** Windows 95/98/Me:** Included in Windows 95 and later.
** Header:** Declared in Mmsystem.h; include Windows.h.