关闭声道

uses MMSystem;

procedure SetMediaAudioOff(DeviceID : word);
var
 SetParm : TMCI_SET_PARMS;
begin
  SetParm.dwAudio := MCI_SET_AUDIO_ALL;
  mciSendCommand(DeviceID,
                 MCI_SET,
                 MCI_SET_AUDIO or MCI_SET_OFF,
                 Longint(@SetParm));
end;

Procedure SetMediaAudioOn(DeviceID : word);
var
 SetParm : TMCI_SET_PARMS;
begin
  SetParm.dwAudio := MCI_SET_AUDIO_ALL;
  mciSendCommand(DeviceID,
                 MCI_SET,
                 MCI_SET_AUDIO or MCI_SET_ON,
                 Longint(@SetParm));
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
 {Play AVI file silently}
  MediaPlayer1.FileName := 'C:\TheWall\DELCAR2.AVI';
  MediaPlayer1.Display := Panel1;
  MediaPlayer1.Open;
  MediaPlayer1.Play;
  SetMediaAudioOff(MediaPlayer1.DeviceId);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
 {Play AVI with sound}
  MediaPlayer1.FileName := 'C:\TheWall\DELCAR2.AVI';
  MediaPlayer1.Display := Panel1;
  MediaPlayer1.Open;
  MediaPlayer1.Play;
  SetMediaAudioOn(MediaPlayer1.DeviceId);
end;