音量调节及静音

在进行多媒体软件开发时，经常要调整各种设备的音量和设置静音，本人编写了一个单元，四个函数，分别用于获取音量（GetVolume(DN))、设置音量(SetVolume(DN,Value))、获取静音（GetVolumeMute(DN)）及设置静音（SetVolumeMute(DN,Value)）。

unit funVolume;

interface

uses MMSystem, Dialogs;

Type TDeviceName = (Master, Microphone, WaveOut, Synth);

function GetVolume(DN:TDeviceName) : Word ;
procedure SetVolume(DN:TDeviceName; Value:Word);
function GetVolumeMute(DN:TDeviceName) : Boolean;
procedure SetVolumeMute(DN:TDeviceName; Value:Boolean);

implementation

//获取音量
function GetVolume(DN:TDeviceName) : Word;
var
hMix: HMIXER;
mxlc: MIXERLINECONTROLS;
mxcd: TMIXERCONTROLDETAILS;
vol: TMIXERCONTROLDETAILS_UNSIGNED;
mxc: MIXERCONTROL;
mxl: TMixerLine;
intRet: Integer;
nMixerDevs: Integer;
begin
// Check if Mixer is available
nMixerDevs := mixerGetNumDevs();
if (nMixerDevs < 1) then
begin
Exit;
end;

// open the mixer
intRet := mixerOpen(@hMix, 0, 0, 0, 0);
if intRet = MMSYSERR_NOERROR then
begin
case DN of
Master : mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
Microphone :
mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE;
WaveOut : mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_WAVEOUT;
Synth : mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_SYNTHESIZER;
end;
mxl.cbStruct := SizeOf(mxl);

// get line info
intRet := mixerGetLineInfo(hMix, @mxl, MIXER_GETLINEINFOF_COMPONENTTYPE);

if intRet = MMSYSERR_NOERROR then
begin
FillChar(mxlc, SizeOf(mxlc),0);
mxlc.cbStruct := SizeOf(mxlc);
mxlc.dwLineID := mxl.dwLineID;
mxlc.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;
mxlc.cControls := 1;
mxlc.cbmxctrl := SizeOf(mxc);

mxlc.pamxctrl := @mxc;
intRet := mixerGetLineControls(hMix, @mxlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);

if intRet = MMSYSERR_NOERROR then
begin
FillChar(mxcd, SizeOf(mxcd),0);
mxcd.dwControlID := mxc.dwControlID;
mxcd.cbStruct := SizeOf(mxcd);
mxcd.cMultipleItems := 0;
mxcd.cbDetails := SizeOf(Vol);
mxcd.paDetails := @vol;
mxcd.cChannels := 1;

intRet := mixerGetControlDetails(hMix, @mxcd,MIXER_SETCONTROLDETAILSF_VALUE);

Result := vol.dwValue ;

if intRet <> MMSYSERR_NOERROR then
ShowMessage(''''GetControlDetails Error'''');
end
else
ShowMessage(''''GetLineInfo Error'''');
end;
intRet := mixerClose(hMix);
end;
end;

//设置音量
procedure setVolume(DN:TDeviceName; Value : Word);
var
hMix: HMIXER;
mxlc: MIXERLINECONTROLS;
mxcd: TMIXERCONTROLDETAILS;
vol: TMIXERCONTROLDETAILS_UNSIGNED;
mxc: MIXERCONTROL;
mxl: TMixerLine;
intRet: Integer;
nMixerDevs: Integer;
begin
// Check if Mixer is available
nMixerDevs := mixerGetNumDevs();
if (nMixerDevs < 1) then
begin
Exit;
end;

// open the mixer
intRet := mixerOpen(@hMix, 0, 0, 0, 0);
if intRet = MMSYSERR_NOERROR then
begin
case DN of
Master : mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
Microphone :
mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE;
WaveOut : mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_WAVEOUT;
Synth : mxl.dwComponentType := MIXERLINE_COMPONENTTYPE_SRC_SYNTHESIZER;
end;
mxl.cbStruct := SizeOf(mxl);

// get line info
intRet := mixerGetLineInfo(hMix, @mxl, MIXER_GETLINEINFOF_COMPONENTTYPE);

if intRet = MMSYSERR_NOERROR then
begin
FillChar(mxlc, SizeOf(mxlc),0);
mxlc.cbStruct := SizeOf(mxlc);
mxlc.dwLineID := mxl.dwLineID;
mxlc.dwControlType := MIXERCONTROL_CONTROLTYPE_VOLUME;
mxlc.cControls := 1;
mxlc.cbmxctrl := SizeOf(mxc);

mxlc.pamxctrl := @mxc;
intRet := mixerGetLineControls(hMix, @mxlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);

if intRet = MMSYSERR_NOERROR then
begin
FillChar(mxcd, SizeOf(mxcd),0);
mxcd.dwControlID := mxc.dwControlID;
mxcd.cbStruct := SizeOf(mxcd);
mxcd.cMultipleItems := 0;
mxcd.cbDetails := SizeOf(Vol);
mxcd.paDetails := @vol;
mxcd.cChannels := 1;

vol.dwValue := Value;

intRet := mixerSetControlDetails(hMix, @mxcd,MIXER_SETCONTROLDETAILSF_VALUE);

if intRet <> MMSYSERR_NOERROR then
ShowMessage(''''SetControlDetails Error'''');
end
else
ShowMessage(''''GetLineInfo Error'''');
end;
intRet := mixerClose(hMix);
end;
end;

//获取静音

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