public static extern int midiStreamOut(IntPtr hms, ref MIDIHDR pmh, int cbmh);
public static extern int midiOutUnprepareHeader(IntPtr hMidiOut, ref MIDIHDR lpMidiOutHdr, int uSize);
public static extern int midiInPrepareHeader(IntPtr hMidiIn, ref MIDIHDR lpMidiInHdr, int uSize);
public static extern int midiOutLongMsg(IntPtr hMidiOut, ref MIDIHDR lpMidiOutHdr, int uSize);
public static extern int midiInAddBuffer(IntPtr hMidiIn, ref MIDIHDR lpMidiInHdr, int uSize);