Как выключить master volume в звуковой карте?

Code:

uses

MMSystem;

function GetMasterMute(

Mixer: hMixerObj;

var Control: TMixerControl): MMResult;

// Returns True on success

var

Line: TMixerLine;

Controls: TMixerLineControls;

begin

ZeroMemory(@Line, SizeOf(Line));

Line.cbStruct := SizeOf(Line);

Line.dwComponentType := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;

Result := mixerGetLineInfo(Mixer, @Line,

   MIXER_GETLINEINFOF_COMPONENTTYPE);

if Result = MMSYSERR_NOERROR then

begin

   ZeroMemory(@Controls, SizeOf(Controls));

   Controls.cbStruct := SizeOf(Controls);

   Controls.dwLineID := Line.dwLineID;

   Controls.cControls := 1;

   Controls.dwControlType := MIXERCONTROL_CONTROLTYPE_MUTE;

   Controls.cbmxctrl := SizeOf(Control);

   Controls.pamxctrl := @Control;

   Result := mixerGetLineControls(Mixer, @Controls,

     MIXER_GETLINECONTROLSF_ONEBYTYPE);

end;

end;

procedure SetMasterMuteValue(

Mixer: hMixerObj;

Value: Boolean);

var

MasterMute: TMixerControl;

Details: TMixerControlDetails;

BoolDetails: TMixerControlDetailsBoolean;

Code: MMResult;

begin

Code := GetMasterMute(0, MasterMute);

if Code = MMSYSERR_NOERROR then

begin

   with Details do

   begin

     cbStruct := SizeOf(Details);

     dwControlID := MasterMute.dwControlID;

     cChannels := 1;

     cMultipleItems := 0;

     cbDetails := SizeOf(BoolDetails);

     paDetails := @BoolDetails;

   end;

   LongBool(BoolDetails.fValue) := Value;

   Code := mixerSetControlDetails(0, @Details,

MIXER_SETCONTROLDETAILSF_VALUE);

end;

if Code <> MMSYSERR_NOERROR then

   raise Exception.CreateFmt('SetMasterMuteValue failure, '+

     'multimedia system error #%d', [Code]);

end;

// Example:

procedure TForm1.Button1Click(Sender: TObject);

begin

SetMasterMuteValue(0, CheckBox1.Checked); // Mixer device #0 mute on/off

end;