Simple Mixer Control Wrapper

最新推荐文章于 2025-12-04 16:58:05 发布

原创最新推荐文章于 2025-12-04 16:58:05 发布 · 547 阅读

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文章标签：

#wrapper #class #object #callback #dst #header

本文介绍了一个小型且实用的C++类CAlexfMixer，它可以封装Windows多媒体混频器控制。通过这个类，可以操作主音量、静音等混频器控制，并获取峰值表等信息。

This is small and useful C++ class which can encapsulate any windows multimedia mixer control.

I wrote a simple class CAlexfMixer to wrap any multimedia mixer control. You can manipulate the Master Volume, Mute or someone elses mixer control with this class, as long as the control support these operations. You can also retrieve information such as the Peak Meter.

Let's look at class definition:

class CAlexfMixer
{
protected:
  HMIXER m_HMixer;
  INT m_iMixerControlID;
  MMRESULT mmr;
  DWORD m_dwChannels;
  BOOL m_bSuccess;
  void ZeroAll();
public:
  BOOL IsOk() {return m_bSuccess;};
  BOOL On();
  BOOL Off();
  DWORD GetControlValue();
  BOOL SetControlValue(DWORD dw);
  CAlexfMixer(DWORD DstType, DWORD SrcType, DWORD ControlType);
  CAlexfMixer(HWND hwnd, DWORD DstType, DWORD SrcType, DWORD ControlType);
  virtual ~CAlexfMixer();
};

The class has two constructors - with and without the callback window. 
The class has member IsOk to check whether the specified control can be manipulated, and member functions to get and set the control's state. 
How it works
Example 1. Master Volume Control. 
 
CAlexfMixer mixer(m_hWnd, MIXERLINE_COMPONENTTYPE_DST_SPEAKERS,
                  NO_SOURCE, MIXERCONTROL_CONTROLTYPE_VOLUME);
if (!mixer.IsOk()) 
   return;
mixer.SetControlValue(500);
 
First we create an object associated with the Master Volume meter control. The third parameter NO_SOURCE is a constant defined in the header file. It means that the control does not have a source line, only a destination line. 
Second we check if is this type of control available or not. 
Finally, we set the volume to 500. 
Example 2. Master Mute. 
 
  
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CAlexfMixer mixer(MIXERLINE_COMPONENTTYPE_DST_SPEAKERS,
                  NO_SOURCE, MIXERCONTROL_CONTROLTYPE_MUTE );
mixer.Off();

Here we create an object associated with Master Mute control, and turn it off. 
  

 


  
 

 
  From:  
  http://www.codeproject.com/KB/audio-video/alexfmixer.aspx