Programmatically-Get-and-Set-the-MediaPlayer-Sound-Volume


            Title: Programmatically Get and Set the MediaPlayer Sound Volume
The TMediaPlayer Delphi component enables your application to control a media playing or recording device such as a CD-ROM player, video player/recorder. 
Here's how to get / set the sound volume while the media is being played in the Media Player.
 uses
 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;
 
 {Set Volume, range 0 - 1000}
 procedure MPSetVolume(MP: TMediaPlayer; Volume: Integer) ;
 var
 p: MCI_DGV_SETAUDIO_PARMS;
 begin
 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;
 
 {Get Volume, range 0 - 1000}
 function MPGetVolume(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;
 end; 
Usage: drop a TMediaPlayer ("MediaPlayer1") along with a TScrollBar ("ScrollBar1") on Delphi form.
In the OnCreate event for the form, setup the scroll bar and load a media file into MediaPlayer:
 procedure TMediaPlayerForm.FormCreate(Sender: TObject) ;
 begin
 ScrollBar1.Min := 0;
 ScrollBar1.Max := 1000;
 
 ScrollBar1.Position := MPGetVolume(MediaPlayer1);
 
 MediaPlayer1.Close;
 MediaPlayer1.FileName:='c:\favorite.mp3';
 MediaPlayer1.Open;
 end; 
Handle the OnChange event of the scroll bar (to set the Media player volume):
 procedure TMediaPlayerForm.ScrollBar1Change(Sender: TObject) ;
 begin
 MPSetVolume(MediaPlayer1, ScrollBar1.Position) ;
 end; 
Note: The related articles box features more TMediaPlayer tutorials and tips.
Multimedia Delphi
