How to programmatically control the volume of my pc?

Question

I have a keyboard without music keys, that for turn up and down the volume, play, stop, etc. of music in my PC. If you don't understand, this is my keyboard and this isn't.

I want to implement, in Windows and in Delphi or C#, a keyboard hook to create the volume feature in my keyboard, but I don't know how to turn up and down it by code. I was trying this and this examples, but didn't work (all in Delphi, by the way).

Do you know how to turn up and down the volume by code?

Answer 1

delphi code follows.

my keyhook sends a message to my main form with the key's VK code in LParam,

procedure TmainFrm.keyHook(var msg: TMessage);
begin
  case msg.LParam of
    VK_VOLUME_UP  : g_mixer.volume := g_mixer.volume + 2048;
    VK_VOLUME_DOWN: g_mixer.volume := g_mixer.volume - 2048;
    VK_VOLUME_MUTE: g_mixer.muted := not g_mixer.muted;
  end;
end;

the volume range is 0 .. 65535; out of band values are silently corrected.

-

unit Mixer;

interface

type

  Tmixer = class
  protected
    function getMute: boolean; virtual; abstract;
    function getVolume: integer; virtual; abstract;
    procedure setVolume(Value: integer); virtual; abstract;
    procedure setMute(Value: boolean); virtual; abstract;
  public
    property volume: integer read getVolume write setVolume;
    property muted: boolean read getMute write setMute;
  end;

function g_mixer: Tmixer;

implementation

uses
  Windows, MMSystem, MMDevApi_tlb, ComObj, ActiveX, SysUtils;

// ---------------------------------------------------------------------------

type

  TxpMixer = class(Tmixer)
  private
    Fmxct: integer;
    Fmixer: HMIXER;
    procedure chk(r: MMRESULT);
  protected
    function getMute: boolean; override;
    function getVolume: integer; override;
    procedure setVolume(Value: integer); override;
    procedure setMute(Value: boolean); override;
  public
    constructor Create;
    destructor Destroy; override;
  end;

  TvistaMixer = class(Tmixer)
  private
    FmmDev: IMMDevice;
    FmmDevEnum: IMMDeviceEnumerator;
    FmmEndpoint: IMMAudioEndpointVolume;
  protected
    function getMute: boolean; override;
    function getVolume: integer; override;
    procedure setVolume(Value: integer); override;
    procedure setMute(Value: boolean); override;
  public
    constructor Create;
  end;

// ---------------------------------------------------------------------------

var
  _g_mixer: Tmixer;

function g_mixer: Tmixer;
var
  VerInfo: TOSVersioninfo;
begin
  if (_g_mixer = nil) then
  begin
    VerInfo.dwOSVersionInfoSize := SizeOf(TOSVersionInfo);
    GetVersionEx(VerInfo);
    if (VerInfo.dwMajorVersion >= 6) then
      _g_mixer := TvistaMixer.Create
    else
      _g_mixer := TxpMixer.Create;
  end;
  result := _g_mixer;
end;

// ---------------------------------------------------------------------------

{ TxpMixer }

procedure TxpMixer.chk(r: MMRESULT);
var
  s: string;
begin
  if (r = MMSYSERR_NOERROR) then
    exit;
  setLength(s, MMSystem.MAXERRORLENGTH + 1);
  waveOutGetErrorText(r, @s[1], MMSystem.MAXERRORLENGTH);
  raise Exception.Create(StrPas(pChar(s)));
end;

// ---------------------------------------------------------------------------

constructor TxpMixer.Create;
begin
  Fmxct := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
  chk(mixerOpen(@Fmixer, 0, 0, 0, 0));
end;

// ---------------------------------------------------------------------------

destructor TxpMixer.Destroy;
begin
  if (Fmixer <> 0) then
    mixerClose(Fmixer);
  inherited;
end;

// ---------------------------------------------------------------------------

function TxpMixer.getMute: boolean;
var
  MasterMute: TMixerControl;
  Details: TMixerControlDetails;
  BoolDetails: TMixerControlDetailsBoolean;
  Line: TMixerLine;
  Controls: TMixerLineControls;
begin
  ZeroMemory(@Line, SizeOf(Line));
  Line.cbStruct := SizeOf(Line);
  Line.dwComponentType := Fmxct;
  chk(mixerGetLineInfo(0, @Line, MIXER_GETLINEINFOF_COMPONENTTYPE));

  ZeroMemory(@Controls, SizeOf(Controls));
  Controls.cbStruct := SizeOf(Controls);
  Controls.dwLineID := Line.dwLineID;
  Controls.cControls := 1;
  Controls.dwControlType := MIXERCONTROL_CONTROLTYPE_MUTE;
  Controls.cbmxctrl := SizeOf(MasterMute);
  Controls.pamxctrl := @MasterMute;
  chk(mixerGetLineControls(0, @Controls, MIXER_GETLINECONTROLSF_ONEBYTYPE));

  Details.cbStruct := SizeOf(Details);
  Details.dwControlID := MasterMute.dwControlID;
  Details.cChannels := 1;
  Details.cMultipleItems := 0;
  Details.cbDetails := SizeOf(BoolDetails);
  Details.paDetails := @BoolDetails;
  chk(mixerGetControlDetails(0, @Details, MIXER_GETCONTROLDETAILSF_VALUE));

  result := BoolDetails.fValue <> 0;
end;

// ---------------------------------------------------------------------------

function TxpMixer.getVolume: integer;
var
  Line: TMixerLine;
  Controls: TMixerLineControls;
  MasterVolume: TMixerControl;
  Details: TMixerControlDetails;
  UnsignedDetails: TMixerControlDetailsUnsigned;
begin
  ZeroMemory(@Line, SizeOf(Line));
  Line.cbStruct := SizeOf(Line);
  Line.dwComponentType := Fmxct;
  chk(mixerGetLineInfo(Fmixer, @Line, MIXER_GETLINEINFOF_COMPONENTTYPE));
  ZeroMemory(@Controls, SizeOf(Controls));
  Controls.cbStruct := SizeOf(Controls);
  Controls.dwLineID := Line.dwLineID;
  Controls.cControls := 1;
  Controls.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;
  Controls.cbmxctrl := SizeOf(MasterVolume);
  Controls.pamxctrl := @MasterVolume;
  chk(mixerGetLineControls(Fmixer, @Controls, MIXER_GETLINECONTROLSF_ONEBYTYPE));

  details.cbStruct := SizeOf(Details);
  details.dwControlID := MasterVolume.dwControlID;
  details.cChannels := 1;
  details.cMultipleItems := 0;
  details.cbDetails := SizeOf(UnsignedDetails);
  details.paDetails := @UnsignedDetails;
  chk(mixerGetControlDetails(Fmixer, @Details, MIXER_GETCONTROLDETAILSF_VALUE));
  result := UnsignedDetails.dwValue;
end;

// ---------------------------------------------------------------------------

procedure TxpMixer.setMute(Value: boolean);
var
  Line: TMixerLine;
  Controls: TMixerLineControls;
  MasterMute: TMixerControl;
  Details: TMixerControlDetails;
  BoolDetails: TMixerControlDetailsBoolean;
begin
  ZeroMemory(@Line, SizeOf(Line));
  Line.cbStruct := SizeOf(Line);
  Line.dwComponentType := Fmxct;
  chk(mixerGetLineInfo(Fmixer, @Line, MIXER_GETLINEINFOF_COMPONENTTYPE));
  ZeroMemory(@Controls, SizeOf(Controls));
  Controls.cbStruct := SizeOf(Controls);
  Controls.dwLineID := Line.dwLineID;
  Controls.cControls := 1;
  Controls.dwControlType := MIXERCONTROL_CONTROLTYPE_MUTE;
  Controls.cbmxctrl := SizeOf(masterMute);
  Controls.pamxctrl := @masterMute;
  chk(mixerGetLineControls(Fmixer, @Controls, MIXER_GETLINECONTROLSF_ONEBYTYPE));

  details.cbStruct := SizeOf(Details);
  details.dwControlID := MasterMute.dwControlID;
  details.cChannels := 1;
  details.cMultipleItems := 0;
  details.cbDetails := SizeOf(BoolDetails);
  details.paDetails := @BoolDetails;
  mixerGetControlDetails(0, @Details, MIXER_GETCONTROLDETAILSF_VALUE);
  if (Value) then
    BoolDetails.fValue := 1
  else
    BoolDetails.fValue := 0;

  chk(mixerSetControlDetails(0, @Details, MIXER_SETCONTROLDETAILSF_VALUE));
end;

// ---------------------------------------------------------------------------

procedure TxpMixer.setVolume(Value: integer);
var 
  Line: TMixerLine;
  Controls: TMixerLineControls;
  MasterVolume: TMixerControl;
  Details: TMixerControlDetails;
  UnsignedDetails: TMixerControlDetailsUnsigned;
begin
  if (value < 0) then
    value := 0;
  if (value > 65535) then
    value := 65535;

  ZeroMemory(@Line, SizeOf(Line));
  Line.cbStruct := SizeOf(Line);
  Line.dwComponentType := Fmxct;
  chk(mixerGetLineInfo(Fmixer, @Line, MIXER_GETLINEINFOF_COMPONENTTYPE));
  ZeroMemory(@Controls, SizeOf(Controls));
  Controls.cbStruct := SizeOf(Controls);
  Controls.dwLineID := Line.dwLineID;
  Controls.cControls := 1;
  Controls.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;
  Controls.cbmxctrl := SizeOf(MasterVolume);
  Controls.pamxctrl := @MasterVolume;
  chk(mixerGetLineControls(Fmixer, @Controls, MIXER_GETLINECONTROLSF_ONEBYTYPE));

  details.cbStruct := SizeOf(Details);
  details.dwControlID := MasterVolume.dwControlID;
  details.cChannels := 1;
  details.cMultipleItems := 0;
  details.cbDetails := SizeOf(UnsignedDetails);
  details.paDetails := @UnsignedDetails;
  UnsignedDetails.dwValue := Value;
  chk(mixerSetControlDetails(Fmixer, @Details, MIXER_SETCONTROLDETAILSF_VALUE));
end;

// ---------------------------------------------------------------------------

{ TvistaMixer }

constructor TvistaMixer.Create;
begin
  CoCreateInstance(CLSID_MMDeviceEnumerator, nil, CLSCTX_ALL, IID_IMMDeviceEnumerator, FmmDevEnum);
  FmmDevEnum.GetDefaultAudioEndpoint(eRender, eMultimedia, FmmDev);
  FmmDev.Activate(IID_IAudioEndpointVolume, CLSCTX_ALL, nil, FmmEndpoint);
end;

// ---------------------------------------------------------------------------

function TvistaMixer.getMute: boolean;
begin
  FmmEndpoint.GetMute(Result);
end;

// ---------------------------------------------------------------------------

function TvistaMixer.getVolume: integer;
var
  VolLevel: Single;
begin
  FmmEndpoint.GetMasterVolumeLevelScalar(VolLevel);
  result := Round(VolLevel * 65535);
end;

// ---------------------------------------------------------------------------

procedure TvistaMixer.setMute(Value: boolean);
begin
  FmmEndpoint.SetMute(Value, nil);
end;

// ---------------------------------------------------------------------------

procedure TvistaMixer.setVolume(Value: integer);
var 
  fValue: Single;
begin
  if (value < 0) then
    value := 0;
  if (value > 65535) then
    value := 65535;
  fValue := Value / 65535;
  FmmEndpoint.SetMasterVolumeLevelScalar(fValue, nil);
end;

// ---------------------------------------------------------------------------

end.

-

unit MMDevApi_tlb;

interface
  uses Windows, ActiveX, Classes, Graphics, OleServer, OleCtrls, StdVCL,ComObj;
const
  // TypeLibrary Major and minor versions

  CLSID_MMDeviceEnumerator: TGUID               = '{BCDE0395-E52F-467C-8E3D-C4579291692E}';
  IID_IMMDeviceEnumerator: TGUID                = '{A95664D2-9614-4F35-A746-DE8DB63617E6}';
  IID_IMMDevice: TGUID                          = '{D666063F-1587-4E43-81F1-B948E807363F}';
  IID_IMMDeviceCollection: TGUID                = '{0BD7A1BE-7A1A-44DB-8397-CC5392387B5E}';
  IID_IAudioEndpointVolume: TGUID               = '{5CDF2C82-841E-4546-9722-0CF74078229A}';
  IID_IAudioMeterInformation : TGUID            = '{C02216F6-8C67-4B5B-9D00-D008E73E0064}';
  IID_IAudioEndpointVolumeCallback: TGUID       = '{657804FA-D6AD-4496-8A60-352752AF4F89}';
  GUID_NULL: TGUID                              = '{00000000-0000-0000-0000-000000000000}';

  DEVICE_STATE_ACTIVE                   = $00000001;
  DEVICE_STATE_UNPLUGGED                = $00000002;
  DEVICE_STATE_NOTPRESENT               = $00000004;
  DEVICE_STATEMASK_ALL                  = $00000007;

type
  EDataFlow = TOleEnum;
const
  eRender                               = $00000000;
  eCapture                              = $00000001;
  eAll                                  = $00000002;
  EDataFlow_enum_count                  = $00000003;

type
  ERole = TOleEnum;
const
  eConsole                              = $00000000;
  eMultimedia                           = $00000001;
  eCommunications                       = $00000002;
  ERole_enum_count                      = $00000003;

type
  IAudioEndpointVolumeCallback = interface(IUnknown)
  ['{657804FA-D6AD-4496-8A60-352752AF4F89}']
  end;

  IMMAudioEndpointVolume = interface(IUnknown)
  ['{5CDF2C82-841E-4546-9722-0CF74078229A}']
    Function RegisterControlChangeNotify( AudioEndPtVol: IAudioEndpointVolumeCallback): Integer; stdcall;
    Function UnregisterControlChangeNotify( AudioEndPtVol: IAudioEndpointVolumeCallback): Integer; stdcall;
    Function GetChannelCount(out PInteger): Integer; stdcall;
    Function SetMasterVolumeLevel(fLevelDB: single; pguidEventContext: PGUID):Integer; stdcall;
    Function SetMasterVolumeLevelScalar(fLevelDB: single; pguidEventContext: PGUID):Integer; stdcall;
    Function GetMasterVolumeLevel(out fLevelDB: single):Integer; stdcall;
    Function GetMasterVolumeLevelScalar(out fLevel: single):Integer; stdcall;
    Function SetChannelVolumeLevel(nChannel: Integer; fLevelDB: double; pguidEventContext: TGUID):Integer; stdcall;
    Function SetChannelVolumeLevelScalar(nChannel: Integer; fLevelDB: single; pguidEventContext: TGUID):Integer; stdcall;
    Function GetChannelVolumeLevel(nChannel: Integer; out fLevelDB: double) : Integer; stdcall;
    Function GetChannelVolumeLevelScalar(nChannel: Integer; out fLevel: double) : Integer; stdcall;
    Function SetMute(bMute: Boolean ; pguidEventContext: PGUID) :Integer; stdcall;
    Function GetMute(out bMute: Boolean ) :Integer; stdcall;
    Function GetVolumeStepInfo( pnStep: Integer; out pnStepCount: Integer):Integer; stdcall;
    Function VolumeStepUp(pguidEventContext: TGUID) :Integer; stdcall;
    Function VolumeStepDown(pguidEventContext: TGUID) :Integer; stdcall;
    Function QueryHardwareSupport(out pdwHardwareSupportMask): Integer; stdcall;
    Function GetVolumeRange(out pflVolumeMindB: double; out pflVolumeMaxdB: double; out pflVolumeIncrementdB: double): Integer; stdcall;
  end;

  IPropertyStore = interface(IUnknown)
  end;

type
  IMMDevice = interface(IUnknown)
  ['{D666063F-1587-4E43-81F1-B948E807363F}']
    Function Activate(  const refId :TGUID;
                        dwClsCtx: DWORD;
                        pActivationParams: PInteger ;
                        out pEndpointVolume: IMMAudioEndpointVolume): Hresult; stdCall;
    Function OpenPropertyStore(stgmAccess: DWORD; out ppProperties :IPropertyStore): Hresult; stdcall;
    Function GetId(out ppstrId: PLPWSTR ): Hresult; stdcall;
    Function GetState(out State :Integer): Hresult; stdcall;
  end;

  IMMDeviceCollection = interface(IUnknown)
  ['{0BD7A1BE-7A1A-44DB-8397-CC5392387B5E}']
  end;

  IMMNotificationClient = interface (IUnknown)
  ['{7991EEC9-7E89-4D85-8390-6C703CEC60C0}']
  end;

  IMMDeviceEnumerator = interface(IUnknown)
  ['{A95664D2-9614-4F35-A746-DE8DB63617E6}']
    Function EnumAudioEndpoints( dataFlow: EDataFlow; deviceState: SYSUINT; DevCollection:IMMDeviceCollection ): Hresult ; stdcall;
    Function GetDefaultAudioEndpoint(EDF: SYSUINT; ER: SYSUINT; out Dev :IMMDevice ): Hresult ; stdcall;
    Function GetDevice( pwstrId: pointer ; out Dev :IMMDevice) : HResult; stdcall;
    Function RegisterEndpointNotificationCallback(pClient :IMMNotificationClient) :Hresult; stdcall;
  end;

  implementation
end.

Answer 2

Autohotkey would do the trick. It has a "SoundSet" command that can adjust volume/mute levels for all audio devices.

Answer 3

This is an addition to glob's excellent answer. SetMute/GetMute function declarations must use 32bit integer values

unit MMDevApi_tlb;
const
  DEVICE_STATE_ACTIVE       = $00000001;
  DEVICE_STATE_UNPLUGGED    = $00000002;
  DEVICE_STATE_NOTPRESENT   = $00000004;
  DEVICE_STATEMASK_ALL      = $00000007;

  IMMAudioEndpointVolume = interface(IUnknown)
  ['{5CDF2C82-841E-4546-9722-0CF74078229A}']
    Function SetMute(iMute: Integer; pguidEventContext: PGUID) :Integer; stdcall;
    Function GetMute(out iMute: Integer) :Integer; stdcall;

Change SetMute and GetMute declaration to use Integer variables and cast Delphi boolean to integer.

method calls are then var iMute: Integer AudioEndVol.SetMute(Integer(CheckBox1.Checked), @GUID_NULL); AudioEndVol.GetMute(iMute);

Using bool does not make trayicon identify mute state properly and unmute does not work at all. Same goes to getmute it must use 32bit integer out parameter or memory alignments are randomly corrupted. I did not understand a reasoning so googled and found an excellent JEDI article.

Some win32 calls are very very picky about the bitwise values, Delphi Bool/Boolean don't always go well with C counterparts. Use 32bit integer to represent C bool variable to have an exact bitwise match. Most win32 C methods are not that strict and work fine with bool/boolean. This specific MMDeviceAPI.SetMute function is a rare corner case and Delphi programmers are hit hard. http://blog.delphi-jedi.net/2008/09/25/bool-boolean-and-integer/