设置TMediaPlayer的音量

uses
 MPlayer, MMSystem;
const
 MCI_SETAUDIO = $0873;
 MCI_DGV_SETAUDIO_VOLUME = $4002;
 MCI_DGV_SETAUDIO_ITEM = $00800000;
 MCI_DGV_SETAUDIO_VALUE = $01000000;
 MCI_DGV_STATUS_VOLUME = $4019;
type
 MCI_DGV_SETAUDIO_PARMS = record
   dwCallback: DWORD;
   dwItem: DWORD;
   dwValue: DWORD;
   dwOver: DWORD;
   lpstrAlgorithm: PChar;
   lpstrQuality: PChar;
 end;
type
 MCI_STATUS_PARMS = record
   dwCallback: DWORD;
   dwReturn: DWORD;
   dwItem: DWORD;
   dwTrack: DWORD;
 end;

procedure SetMPVolume(MP: TMediaPlayer; Volume: Integer);
 { Volume: 0 - 1000 }
var
 p: MCI_DGV_SETAUDIO_PARMS;
begin
 { Volume: 0 - 1000 }
 p.dwCallback := 0;
 p.dwItem := MCI_DGV_SETAUDIO_VOLUME;
 p.dwValue := Volume;
 p.dwOver := 0;
 p.lpstrAlgorithm := nil;
 p.lpstrQuality := nil;
 mciSendCommand(MP.DeviceID, MCI_SETAUDIO,
   MCI_DGV_SETAUDIO_VALUE or MCI_DGV_SETAUDIO_ITEM, Cardinal(@p));
end;

function GetMPVolume(MP: TMediaPlayer): Integer;
var  
 p: MCI_STATUS_PARMS;
begin
 p.dwCallback := 0;
 p.dwItem := MCI_DGV_STATUS_VOLUME;
 mciSendCommand(MP.DeviceID, MCI_STATUS, MCI_STATUS_ITEM, Cardinal(@p));
 Result := p.dwReturn;
 { Volume: 0 - 1000 }
end;

// Example, Beispiel:
procedure TForm1.Button1Click(Sender: TObject);
begin
 SetMPVolume(MediaPlayer1, 500);
end;