如何检查系统主音量是否静音或取消静音？ [英] How to check if the system master volume is mute or unmute?

问题描述

我正在使用此代码来静音/取消静音系统主卷：

I'm using this code to mute/unmute system master volume:

const
  APPCOMMAND_VOLUME_MUTE = $80000;
  WM_APPCOMMAND = $319;

procedure TForm1.Button1Click(Sender: TObject);
begin
  // toggle mute/unmute
  SendMessageW(Handle, WM_APPCOMMAND, Handle, APPCOMMAND_VOLUME_MUTE);
end;

（得到 http://stackoverflow.com/a/154128/1140885 ）

它在XP上工作正常（没有在Win7上测试还有）

我需要一个方法来检查（get）当前的静音状态是什么？是否静音？

任何想法？

It works fine on XP (Didn't test it on Win7 yet).
I need a method to check (get) what is the current "mute" state? Is it mute or not.
Any ideas?

更新：对于 XP 我最终使用这里的代码：如何获取Windows XP中的主卷？（感谢@ Sertac Akyuz）

Update: For XP I ended up using the code from here: How to get the master volume in windows xp? (Thanks to @Sertac Akyuz)

我只需更改一行：

mxlc.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;

to：

mxlc.dwControlType := MIXERCONTROL_CONTROLTYPE_MUTE;

返回值为0（不静音）或1（静音）。

return value is either 0 (not mute) or 1 (mute).

推荐答案

从Windows Vista开始，您必须使用 Core Audio SDK 来控制Windows音频。要检查主音量是否静音，您必须使用 IAudioEndpointVolume.GetMute 方法。

Starting with Windows Vista you must use the Core Audio SDK to control the Windows audio. To check if the master volume is muted you must use the IAudioEndpointVolume.GetMute method.

尝试此示例代码

{$APPTYPE CONSOLE}

uses
  SysUtils,
  Windows,
  ActiveX,
  ComObj;

const
  CLASS_IMMDeviceEnumerator : TGUID = '{BCDE0395-E52F-467C-8E3D-C4579291692E}';
  IID_IMMDeviceEnumerator : TGUID = '{A95664D2-9614-4F35-A746-DE8DB63617E6}';
  IID_IAudioEndpointVolume : TGUID = '{5CDF2C82-841E-4546-9722-0CF74078229A}';

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

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

  IAudioMeterInformation = interface(IUnknown)
  ['{C02216F6-8C67-4B5B-9D00-D008E73E0064}']
  end;

  IPropertyStore = interface(IUnknown)
  end;

  IMMDevice = interface(IUnknown)
  ['{D666063F-1587-4E43-81F1-B948E807363F}']
    function Activate(const refId: TGUID; dwClsCtx: DWORD;  pActivationParams: PInteger; out pEndpointVolume: IAudioEndpointVolume): 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: TOleEnum; 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;

function IsMasterVolumeMute : Boolean;
var
  pEndpointVolume: IAudioEndpointVolume;
  LDeviceEnumerator: IMMDeviceEnumerator;
  Dev: IMMDevice;
  bMute: Boolean;
begin
  if not Succeeded(CoCreateInstance(CLASS_IMMDeviceEnumerator, nil, CLSCTX_INPROC_SERVER, IID_IMMDeviceEnumerator, LDeviceEnumerator)) then
   RaiseLastOSError;
  if not Succeeded(LDeviceEnumerator.GetDefaultAudioEndpoint($00000000, $00000000, Dev)) then
   RaiseLastOSError;

  if not Succeeded( Dev.Activate(IID_IAudioEndpointVolume, CLSCTX_INPROC_SERVER, nil, pEndpointVolume)) then
   RaiseLastOSError;

  if not Succeeded(pEndpointVolume.GetMute(bMute)) then
   RaiseLastOSError
  else
  Result:=bMute;
end;


begin
 try
    CoInitialize(nil);
    try
      Writeln(Format('Master Volume is Mute ? : %s',[BoolToStr(IsMasterVolumeMute, True)]));
    finally
      CoUninitialize;
    end;
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;
end.

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