Question

我想以编程方式调整音量，例如vista和xp中的Get / SetMasterVolume？使用mmsystem单元？

Answer 1

以下是音频通用api的实现：MMDevApi

http://social.msdn.microsoft.com/Forums/en/windowspro-audiodevelopment/thread/5ce74d5d-2b1e-4ca9-a8c9-2e27eb9ec058

以及带按钮的示例

unit Unit33;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, MMDevApi, ActiveX, StdCtrls;

type
  TForm33 = class(TForm)
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form33: TForm33;
  endpointVolume: IAudioEndpointVolume = nil;

implementation

{$R *.dfm}


procedure TForm33.Button1Click(Sender: TObject);
var
  VolumeLevel: Single;
begin
  if endpointVolume = nil then Exit;
  VolumeLevel := 0.50;
  endpointVolume.SetMasterVolumeLevelScalar(VolumeLevel, nil);
  Caption := Format('%1.8f', [VolumeLevel])
end;

procedure TForm33.FormCreate(Sender: TObject);
var
  deviceEnumerator: IMMDeviceEnumerator;
  defaultDevice: IMMDevice;
begin
  CoCreateInstance(CLASS_IMMDeviceEnumerator, nil, CLSCTX_INPROC_SERVER, IID_IMMDeviceEnumerator, deviceEnumerator);
  deviceEnumerator.GetDefaultAudioEndpoint(eRender, eConsole, defaultDevice);
  defaultDevice.Activate(IID_IAudioEndpointVolume, CLSCTX_INPROC_SERVER, nil, endpointVolume);
end;

end.

Answer 2

Windows XP：

function SetMasterVolume(VolToSet: word; out VolSet: word): MMResult;
var
  MixerHandle: HMixer;
  Volume: TMixerControlDetails_Unsigned;
  MixerLine: TMixerLine;
  MixerLineControls: TMixerLineControls;
  VolumeCtrl: TMixerControl;
  MixerControlDetails: TMixerControlDetails;
begin
  // Get mixer handle
  Result := mixerOpen(@MixerHandle, 0, 0, 0, 0);
  if Result <> MMSYSERR_NOERROR then Exit;
  try
    // Get master volume line
    FillChar(MixerLine, SizeOf(TMixerLine), 0);
    MixerLine.cbStruct := SizeOf(TMixerLine);
    MixerLine.dwComponentType := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
    Result := mixerGetLineInfo(MixerHandle, @MixerLine, MIXER_GETLINEINFOF_COMPONENTTYPE);

    if Result <> MMSYSERR_NOERROR then Exit;
    // Get the volume control of the master volume line
    FillChar(VolumeCtrl, SizeOf(TMixerControl), 0);
    MixerLineControls.cbStruct := SizeOf(TMixerLineControls);
    MixerLineControls.dwLineID := MixerLine.dwLineID;
    MixerLineControls.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;
    MixerLineControls.cControls := 1;
    MixerLineControls.cbmxctrl := SizeOf(TMixerControl);
    MixerLineControls.pamxctrl := @VolumeCtrl;
    Result := mixerGetLineControls(MixerHandle,@MixerLineControls,MIXER_GETLINECONTROLSF_ONEBYTYPE);

    if Result <> MMSYSERR_NOERROR then Exit;
    // Set details (volume) for the volume control of the master volume line
    FillChar(MixerControlDetails, SizeOf(TMixerControlDetails), 0);
    MixerControlDetails.cbStruct := SizeOf(TMixerControlDetails);
    MixerControlDetails.dwControlID := VolumeCtrl.dwControlID;
    MixerControlDetails.cChannels := 1;
    MixerControlDetails.cMultipleItems := 0;
    MixerControlDetails.cbDetails := SizeOf(TMixerControlDetails_Unsigned);
    MixerControlDetails.paDetails := @Volume;
    Volume.dwValue := VolToSet;
    Result := mixerSetControlDetails(MixerHandle, @MixerControlDetails,MIXER_SETCONTROLDETAILSF_VALUE);
  finally
    mixerClose(MixerHandle);
  end;
end;

电话：

var y:word;
begin
  SetMasterVolume(2000,y);
end;

Answer 3

MMDevApi有许多不正确的声明。双参数应该是单一的。布尔参数更好地作为整数。并且许多（如果不是全部）TGUID参数应该是PGUID。在更正声明之后，我能够设置静音和音量级别。

如何在vista / xp中调整主音量

3 个答案: