获取、设置声卡音量的方法

在Windows XP中：

获取音量的方法：

第一步：获取线路的信息：

	MIXERLINE mxl;
	MMRESULT rc;
	ZeroMemory(&mxl,sizeof(MIXERLINE));
	mxl.cbStruct = sizeof(MIXERLINE);
	mxl.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS;
	rc = mixerGetLineInfo((HMIXEROBJ)hMixer, &mxl,
		MIXER_GETLINEINFOF_COMPONENTTYPE);
	if (MMSYSERR_NOERROR != rc) {
		mixerClose(hMixer);
		return LUCE_DRV_FAIL;
	}
 
  
 
  
 
  
 
  
传入的第二个参数，mxl设置类型为MIXERLINE_COMPONENTTYPE_DST_SPEAKERS，表示线路中的控件类型是音量控件。第三个参数，设置为MIXER_GETLINEINFOF_COMPONENTTYPE，表示根据类型去获取线路信息。获取成功，则返回MMSYSERR_NOERROR。
 
  
第二步，获取该线路的控制信息：
 
  
 
  
	MIXERCONTROL mxc;         /* Holds the mixer control data */
	/* Get the control */
	ZeroMemory(&mxc, sizeof(MIXERCONTROL));
	mxc.cbStruct = sizeof(mxc);
	ZeroMemory(&mxlc, sizeof(MIXERLINECONTROLS));
	mxlc.cbStruct = sizeof(mxlc);
	mxlc.dwLineID = mxl.dwLineID;
	mxlc.dwControlType = MIXERCONTROL_CONTROLTYPE_VOLUME;
	mxlc.cControls = 1;
	mxlc.pamxctrl = &mxc;
	mxlc.cbmxctrl = sizeof(mxc);
	rc = mixerGetLineControls((HMIXEROBJ)hMixer,&mxlc, MIXER_GETLINECONTROLSF_ONEBYTYPE);
	if (MMSYSERR_NOERROR != rc) {
		mixerClose(hMixer);
		/* Couldn't get the control*/
		return LUCE_DRV_FAIL;
	}
 
   
  用 
  mixerGetLineControls获取线路中的控件信息。将上一步获取的到线路信息设置到mxlc中，直接获取一个控件，第三个设置为MIXER_GETLINECONTROLSF_ONEBYTYPE也是通过类型是检索控件。调用之后相关的控制信息，会设置到mxlc的pamxctrl，即mxc中。 
  
 
  
第三步：
 
  
 
  
ZeroMemory(&mxcd, sizeof(mxcd));
	mxcd.cbStruct = sizeof(mxcd);
	mxcd.cbDetails = sizeof(unsigned long);
	mxcd.dwControlID = mxc.dwControlID;
	mxcd.paDetails = &volStruct;
	mxcd.cChannels = MIXERCONTROL_CONTROLF_UNIFORM;
	mxcd.cMultipleItems = 0;

	/* Get the current value of the peakmeter control. Typically, you
	would set a timer in your program to query the volume every 10th
	of a second or so.
	*/
	rc = mixerGetControlDetails((HMIXEROBJ)hMixer, &mxcd,
		MIXER_GETCONTROLDETAILSF_VALUE);
	if (MMSYSERR_NOERROR != rc) {
		mixerClose(hMixer);
		/* Couldn't get the current volume */
		return LUCE_DRV_FAIL;
	}
 
   
  
用mixerGetControlDetails获取控件的详细信息，获取到的信息，放在mxcd的paDetails中。MIXERCONTROL_CONTROLF_UNIFORM 表示 所有线路的通道只有一个共同的音量控制。
 
  
设置音量的方法：
 
  
前三步和获取音量的方法一样，区别是：第四步，获取到当前的音量之后，把将要设置的音量值传给paDetails。再调用mixerSetControlDetails将值设置到系统中。
 
  
 
  
volStruct.lValue= lVol;
rc = mixerSetControlDetails((HMIXEROBJ)hMixer, &mxcd,
		MIXER_GETCONTROLDETAILSF_VALUE);
	if (MMSYSERR_NOERROR != rc) {
		mixerClose(hMixer);
		/* Couldn't get the current volume */
		return LUCE_DRV_FAIL;
	}
 
  

 
  
在Windows Vista之后的系统中，MS换了API，直接贴代码吧~
 
  
BOOL Volume_set(DWORD dwVolume,BOOL IsMixer/*TRUE*/)
{
	HRESULT hr = S_OK;		
	IMMDeviceCollection *pMultiDevice = NULL;
	IMMDevice *pDevice = NULL;
	IAudioSessionEnumerator *pSessionEnum = NULL;

	if (IsMixer)
	{
		// 播放
		hr = m_pEnumerator->EnumAudioEndpoints(eRender,DEVICE_STATE_ACTIVE, &pMultiDevice);
	} 
	else
	{
		// 录音
		hr = m_pEnumerator->EnumAudioEndpoints(eCapture,DEVICE_STATE_ACTIVE, &pMultiDevice);
	}
	if(FAILED(hr))
		return FALSE;
	UINT deviceCount = 0;
	hr = pMultiDevice->GetCount(&deviceCount);      
	if(FAILED(hr))
		return FALSE;  
		
	if((int)dwVolume < 0)
		dwVolume = 0;
	if((int)dwVolume > 100)
		dwVolume = 100;
	for (UINT ii=0; iiItem(ii,&pDevice);    
		if(FAILED(hr))
			return FALSE;  
		hr = pDevice->Activate(__uuidof(IAudioEndpointVolume),CLSCTX_ALL, NULL, (void**)&pEndptVolCtrl);  
		if(FAILED(hr))
			return FALSE;  
		// 使用 IAudioEndpintVolume 的方法获取音量，设置音量，设置静音等    
		HRESULT hr = pEndptVolCtrl->SetMasterVolumeLevelScalar((float)dwVolume / 100, &m_guidMyContext);  
		
		if(FAILED(hr))
			return FALSE;  
		SAFE_RELEASE(pDevice);
	}
	return TRUE;
}
 
  
其中，
 
  
#define SAFE_RELEASE(punk)  \
	if ((punk) != NULL)  \
{ (punk)->Release(); (punk) = NULL; }