how to adjust master volume in vista/xp

Question

i want to adjust the volume programatically like Get/SetMasterVolume in vista and xp? using mmsystem unit?

Answer 1

Windows XP:

function SetMasterVolume(VolToSet: word; out VolSet: word): MMResult;
var
  MixerHandle: HMixer;
  Volume: TMixerControlDetails_Unsigned;
  MixerLine: TMixerLine;
  MixerLineControls: TMixerLineControls;
  VolumeCtrl: TMixerControl;
  MixerControlDetails: TMixerControlDetails;
begin
  // Get mixer handle
  Result := mixerOpen(@MixerHandle, 0, 0, 0, 0);
  if Result <> MMSYSERR_NOERROR then Exit;
  try
    // Get master volume line
    FillChar(MixerLine, SizeOf(TMixerLine), 0);
    MixerLine.cbStruct := SizeOf(TMixerLine);
    MixerLine.dwComponentType := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
    Result := mixerGetLineInfo(MixerHandle, @MixerLine, MIXER_GETLINEINFOF_COMPONENTTYPE);

    if Result <> MMSYSERR_NOERROR then Exit;
    // Get the volume control of the master volume line
    FillChar(VolumeCtrl, SizeOf(TMixerControl), 0);
    MixerLineControls.cbStruct := SizeOf(TMixerLineControls);
    MixerLineControls.dwLineID := MixerLine.dwLineID;
    MixerLineControls.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;
    MixerLineControls.cControls := 1;
    MixerLineControls.cbmxctrl := SizeOf(TMixerControl);
    MixerLineControls.pamxctrl := @VolumeCtrl;
    Result := mixerGetLineControls(MixerHandle,@MixerLineControls,MIXER_GETLINECONTROLSF_ONEBYTYPE);

    if Result <> MMSYSERR_NOERROR then Exit;
    // Set details (volume) for the volume control of the master volume line
    FillChar(MixerControlDetails, SizeOf(TMixerControlDetails), 0);
    MixerControlDetails.cbStruct := SizeOf(TMixerControlDetails);
    MixerControlDetails.dwControlID := VolumeCtrl.dwControlID;
    MixerControlDetails.cChannels := 1;
    MixerControlDetails.cMultipleItems := 0;
    MixerControlDetails.cbDetails := SizeOf(TMixerControlDetails_Unsigned);
    MixerControlDetails.paDetails := @Volume;
    Volume.dwValue := VolToSet;
    Result := mixerSetControlDetails(MixerHandle, @MixerControlDetails,MIXER_SETCONTROLDETAILSF_VALUE);
  finally
    mixerClose(MixerHandle);
  end;
end;

And the call:

var y:word;
begin
  SetMasterVolume(2000,y);
end;