Set Volume for Microphone

uses MMSystem

//

function SetMicrophoneVolume(bValue: Word): Boolean;
var                          {0..65535}
  hMix: HMIXER;
  mxlc: MIXERLINECONTROLS;
  mxcd: TMIXERCONTROLDETAILS;
  vol: TMIXERCONTROLDETAILS_UNSIGNED;
  mxc: MIXERCONTROL;
  mxl: TMixerLine;
  intRet: Integer;
  nMixerDevs: Integer;
begin
  // Check if Mixer is available
  nMixerDevs := mixerGetNumDevs();
  if (nMixerDevs < 1) then
  begin
    Exit;
  end;

  // open the mixer
  intRet := mixerOpen(@hMix, 0, 0, 0, 0);
  if intRet = MMSYSERR_NOERROR then
  begin
    mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE;
    mxl.cbStruct        := SizeOf(mxl);

    {*}    // this option will tell the compiler which line destination to take:
    {*}    // 0 - PLAYBACK destination
    {*}    // 1 - RECORD destination
    {*}    // this time the compiler will take control of recording microphone line
    {*}    mxl.dwDestination := 1;

    // get line info
    intRet := mixerGetLineInfo(hMix, @mxl, MIXER_GETLINEINFOF_COMPONENTTYPE);
  end;
end;

Beispiel :

procedure TForm1.ScrollBar1Change(Sender: TObject);
begin
  // Set Value {0..65535}
  SetMicrophoneVolume(ScrollBar1.Position);
end;