windows 下控制声音输出

在 vista 以上的操作系统中，可以使用 IAudioMeterInformation 获取音频信息。

CoInitialize(NULL);
IMMDeviceEnumerator *pEnum = NULL;
IMMDevice *pDevice = NULL;
IAudioMeterInformation *pMeter = NULL;
float peak;

HRESULT hr;
hr = CoCreateInstance(__uuidof(MMDeviceEnumerator),
                      NULL,
                      CLSCTX_INPROC_SERVER,
                      __uuidof(IMMDeviceEnumerator),
                      (void**)&pEnum);

hr = pEnum -> GetDefaultAudioEndpoint(eRender, eConsole, &pDevice);

pDevice -> Activate(__uuidof(IAudioMeterInformation),
                    CLSCTX_ALL,
                    NULL,
                    (void**)&pMeter);

pMeter -> GetPeakValue(&peak); // I need this value

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Winapi.ActiveX, System.Win.ComObj, MMSystem,
  Vcl.ComCtrls, Vcl.ExtCtrls;

type
  EDATAFLOW = TOleEnum;
  EROLE = TOleEnum;

  IMMDevice = interface(IUnknown)
    ['{D666063F-1587-4E43-81F1-B948E807363F}']
    function Activate(const iid: TGUID; const dwClsCtx: UINT; const pActivationParams: PPropVariant; out ppInterface: IUnknown)
      : HRESULT; stdcall;
  end;

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

  IMMDeviceEnumerator = interface(IUnknown)
    ['{A95664D2-9614-4F35-A746-DE8DB63617E6}']
    function EnumAudioEndpoints(const dataFlow: EDATAFLOW; const dwStateMask: DWORD; out ppDevices: IMMDeviceCollection): HRESULT; stdcall;
    function GetDefaultAudioEndpoint(const dataFlow: EDATAFLOW; const role: EROLE; out ppEndpoint: IMMDevice): HRESULT; stdcall;
  end;

  IAudioMeterInformation = interface(IUnknown)
    ['{C02216F6-8C67-4B5B-9D00-D008E73E0064}']
    function GetPeakValue(out pfPeak: Single): HRESULT; stdcall;
    function GetMeteringChannelCount(out pnChannelCount: UINT): HRESULT; stdcall;
    function GetChannelsPeakValues(u32ChannelCount: UINT; out afPeakValues: pSingle): HRESULT; stdcall;
    function QueryHardwareSupport(out pdwHardwareSupportMask: UINT): HRESULT; stdcall;
  end;

  TForm1 = class(TForm)
    ProgressBar1: TProgressBar;
    Timer1: TTimer;
    procedure FormCreate(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

const
  IID_IMMDeviceEnumerator: TGUID = '{A95664D2-9614-4F35-A746-DE8DB63617E6}';
  CLASS_IMMDeviceEnumerator: TGUID = '{BCDE0395-E52F-467C-8E3D-C4579291692E}';
  IID_IAudioMeterInformation: TGUID = '{C02216F6-8C67-4B5B-9D00-D008E73E0064}';
  eRender = $00000000;
  eConsole = $00000000;

var
  Form1: TForm1;
  peak: IAudioMeterInformation = nil;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);

var
  device: IMMDevice;
  deviceEnumerator: IMMDeviceEnumerator;
begin
  Timer1.Enabled := False;
  ProgressBar1.Max := 65535; 
  CoCreateInstance(CLASS_IMMDeviceEnumerator, nil, CLSCTX_ALL, IID_IMMDeviceEnumerator, deviceEnumerator);
  deviceEnumerator.GetDefaultAudioEndpoint(eRender, eConsole, device);
  device.Activate(IID_IAudioMeterInformation, CLSCTX_ALL, nil, IUnknown(peak));
  Timer1.Enabled := true;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
var
  Temp: Single;
begin
  peak.GetPeakValue(Temp);
  ProgressBar1.position := Round(Temp * 65535);
end;

end.

UsingAudioVolumeControlApi.pas

(*
  Category: SWAG Title: Borland DELPHI
  Original name: 0424.PAS
  Description: Using Audio Volume Control API
  Author: SWAG SUPPORT TEAM
  Date: 01-02-98  07:34
*)

//
unit WaveUnit;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls,
  Forms, Dialogs, MMSystem, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    {Private declarations}
  public
    {Public declarations}
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var
 NumDevs     : Integer;
 waveCaps    : TWaveOutCaps;
 Volume      : DWORD;
 Left, Right : Word;
 Version     : Word;
begin
// We should have at least one device
  NumDevs := waveOutGetNumDevs;
  Edit1.Text := Format('Number of devices is %d', [NumDevs]);
// for the 1st device (hard-coded)
// Get Device Caps
  waveOutGetDevCaps(0, @waveCaps, SizeOf(waveCaps));
// Show device caps
  Memo1.Lines.Add('IατΓαφΦσ: '+waveCaps.szPName);
  Version := waveCaps.vDriverVersion;
  Memo1.Lines.Add(Format('Aσd±Φ  ΣdαΘΓσdα: %d.%d', [Hi(Version), Lo(Version)]));
  Case waveCaps.wChannels of
    1 : Memo1.Lines.Add('Iεφε');
    2 : Memo1.Lines.Add('╤≥σdσε');
  End;
 // Standard formats

 If waveCaps.dwFormats AND WAVE_FORMAT_1M08 <> 0 Then
  Memo1.Lines.Add('11.025 kHz, mono, 8-bit');
 If waveCaps.dwFormats AND WAVE_FORMAT_1M16 <> 0 Then
  Memo1.Lines.Add('11.025 kHz, mono, 16-bit');
{
WAVE_FORMAT_1S08    11.025 kHz, stereo, 8-bit
WAVE_FORMAT_1S16    11.025 kHz, stereo, 16-bit
WAVE_FORMAT_2M08    22.05 kHz, mono, 8-bit
WAVE_FORMAT_2M16    22.05 kHz, mono, 16-bit
WAVE_FORMAT_2S08    22.05 kHz, stereo, 8-bit
WAVE_FORMAT_2S16    22.05 kHz, stereo, 16-bit
WAVE_FORMAT_4M08    44.1 kHz, mono, 8-bit
WAVE_FORMAT_4M16    44.1 kHz, mono, 16-bit
WAVE_FORMAT_4S08    44.1 kHz, stereo, 8-bit
WAVE_FORMAT_4S16    44.1 kHz, stereo, 16-bit
}

// If Volume Control Supported
  If waveCaps.dwSupport AND WAVECAPS_VOLUME <> 0 Then
   Begin
    waveOutGetVolume(0, @Volume);
    Left  := LoWord(Volume);
    Right := HiWord(Volume);
// Show values of WAVE Device on volume control panel
    Edit2.Text := Format('Left : %d, Right : %d', [Left, Right]);
   waveOutSetVolume(0, $40008000);
   End;
end;

end.

windows 下控制声音输出

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