Example of controling the sound volume from Delphi

uses MMSystem;

type

  TVolumeRec = record

    case Integer of

      0: (LongVolume: Longint);

      1: (LeftVolume, RightVolume: Word);

  end;

const

  DeviceIndex = 5{0:Wave  1:MIDI  2:CDAudio  3:Line-In  4:Microphone  5:Master  6:PC-loudspeaker}

procedure SetVolume(aVolume: Byte);

var

  Vol: TVolumeRec;

begin

  Vol.LeftVolume := aVolume shl 8;

  Vol.RightVolume :=

  Vol.LeftVolume;

  auxSetVolume(UINT(DeviceIndex), Vol.LongVolume);

end;

function GetVolume: Cardinal;

var

  Vol: TVolumeRec;

begin

  AuxGetVolume(UINT(DeviceIndex), @Vol.LongVolume);

  Result := (Vol.LeftVolume + Vol.RightVolume) shr 9;

end;