Question

我有一个非常简单的应用程序，用于在Windows 7上运行的Delphi 2007中播放我的音乐集。我向Windows Media Player外壳以避免Delphi Media Player组件拒绝播放某些曲目我扔了它。我现在想从应用程序中控制扬声器的音量。

此时我说“扬声器音量”＆＃39;而不是“WMP量”＆＃39;因为我认为控制WMP的音量比控制所有应用程序的整体扬声器/主音量要困难。

我确信这在过去非常简单，但操作系统变得更加复杂，我找到并尝试过的所有代码片段都不适用于控制扬声器的主/核心卷。< / p>

是否可以从运行在Windows 7上的Delphi 2007中控制此主卷？

如果是，那么我可以非常感谢像GetVolume和SetVolume这样的一些函数来完成这样一个基本任务。

我查看了过去提出的类似问题，但我并不抱有希望。

布鲁斯。

Answer 1

在Windows 7下，您必须使用Core Audio SDK来控制Windows音频。在这里，您可以尝试IAudioEndpointVolume::SetMasterVolumeLevelScalar或IAudioEndpointVolume::SetMasterVolumeLevel方法。

尝试使用SetMasterVolumeLevelScalar方法的代码。

{$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;

procedure SetMasterVolume(fLevelDB: single);
var
  pEndpointVolume: IAudioEndpointVolume;
  LDeviceEnumerator: IMMDeviceEnumerator;
  Dev: IMMDevice;
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.SetMasterVolumeLevelScalar(fLevelDB, nil)) then
   RaiseLastOSError;
end;


begin
 try
    CoInitialize(nil);
    try
      SetMasterVolume(1.0); //set the volume to the max
      Sleep(2000);
      SetMasterVolume(0.5); //set the volume to the 50 %
      Sleep(2000);
      SetMasterVolume(0.1); //set the volume to the 10 %
      Sleep(2000);
    finally
      CoUninitialize;
    end;
 except
    on E:Exception do
        Writeln(E.Classname, ':', E.Message);
 end;
 Writeln('Press Enter to exit');
 Readln;
end.

在Windows 7中控制主扬声器音量

1 个答案: