Control Wave Volume

ExtCtrls, MMSystem, Spin

//

function GetWaveVolume(var LVol: DWORD; var RVol: DWORD): Boolean;
var
  WaveOutCaps: TWAVEOUTCAPS;
  Volume: DWORD;
begin
  Result := False;
  if WaveOutGetDevCaps(WAVE_MAPPER, @WaveOutCaps, SizeOf(WaveOutCaps)) = MMSYSERR_NOERROR then
    if WaveOutCaps.dwSupport and WAVECAPS_VOLUME = WAVECAPS_VOLUME then
    begin
      Result := WaveOutGetVolume(WAVE_MAPPER, @Volume) = MMSYSERR_NOERROR;
      LVol   := LoWord(Volume);
      RVol   := HiWord(Volume);
    end;
end;

function SetWaveVolume(const AVolume: DWORD): Boolean;
var
  WaveOutCaps: TWAVEOUTCAPS;
begin
  Result := False;
  if WaveOutGetDevCaps(WAVE_MAPPER,
                       @WaveOutCaps,
                       SizeOf(WaveOutCaps)) = MMSYSERR_NOERROR then
    if WaveOutCaps.dwSupport and WAVECAPS_VOLUME = WAVECAPS_VOLUME then
      Result := WaveOutSetVolume(WAVE_MAPPER, AVolume) = MMSYSERR_NOERROR;
end;



procedure TForm1.Button1Click(Sender: TObject);
var
  LVol: Word;
  RVol: Word;
begin
  LVol := SpinEdit1.Value;  // max. is 65535
  RVol := SpinEdit2.Value;  // max. is 65535
  SetWaveVolume(MakeLong(LVol, RVol));
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  LVol: DWORD;
  RVol: DWORD;
begin
  if GetWaveVolume(LVol, RVol) then
  begin
    SpinEdit1.Value := LVol;
    SpinEdit2.Value := RVol;
  end;
end;