procedure TMidiOutput.PutLong(TheSysex: Pointer; msgLength: Word);
{ Notes: This works asynchronously }
var
  MyMidiHdr: TMyMidiHdr;
begin
  { Initialize the header and allocate buffer memory }
  MyMidiHdr := TMyMidiHdr.Create(msgLength);
  StrMove(MyMidiHdr.SysexPointer, TheSysex, msgLength);
  { Store the MyMidiHdr address in the header so we can find it again quickly }
  MyMidiHdr.hdrPointer^.dwUser := DWORD(MyMidiHdr);
  { Get MMSYSTEM's blessing for this header }
  FError := midiOutPrepareHeader(FMidiHandle, MyMidiHdr.hdrPointer, sizeof(TMIDIHDR));
  if Ferror > 0 then
    raise EMidiOutputError.Create(MidiIOErrorString(False, FError));
  { Send it }
  FError := midiOutLongMsg(FMidiHandle, MyMidiHdr.hdrPointer, sizeof(TMIDIHDR));
  if FError > 0 then
    raise EMidiOutputError.Create(MidiIOErrorString(False, FError));
end;