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Volume Manipulation Classes

, 16 Nov 1999
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Volume manipulation classes.

Introduction

Many times my applications required audio volume manipulation. To make the volume-enabled application development easier, I decided to create a few C++ classes that would allow me to easily regulate and track the changes of such volume controls as Output Master Volume, WaveOut Volume and Input (WaveIn) Volume. Here I provide such classes that share a common interface (defined in IVolume.h):

  • bool IsAvailable() - Says whether the volume controlling is possible.
  • void Enable() - Enables the line of the volume control.
  • void Disable() - Disables the line of the volume control.
  • DWORD GetVolumeMetric() - Retrieves the granularity of volume.
  • DWORD GetMinimalVolume() - Retrieves the minimal volume that can be set.
  • DWORD GetMaximalVolume() - Retrieves the maximal volume that can be set.
  • DWORD GetCurrentVolume() - Retrieves the current volume.
  • void SetCurrentVolume( DWORD dwValue ) - Sets the volume.

And the last function allows to register a user-implemented callback that will be called as a notification of volume changes:

void RegisterNotificationSink( PONMICVOULUMECHANGE, DWORD )

This interface is implemented by CVolumeOutMaster (VolumeOutMaster.h/cpp), CVolumeOutWave (VolumeOutWave.h/cpp) and CVolumeInXXX (VolumeInXXX.h/cpp) classes. The usage of the classes is very simple:

In your StdAfx.h, include "mmSystem.h" and make sure you link to the "winmm.lib" (#pragma comment(lib, "winmm.lib")). Then, if you are going to use Output Mater volume control, include "VolumeOutMaster.h", say, to the StdAfx.h.

The IVolume.h, VolumeInXXX.h, VolumeInXXX.cpp are to be inserted as your project files.

...
void CALLBACK MasterVolumeChanged( DWORD dwCurrentVolume, DWORD dwUserValue );
...
// Volume control Initialization
IVolume* pMasterVolume = (IVolume*)new CVolumeOutMaster();
if ( !pMasterVolume || !pMasterVolume->IsAvailable() )
{
    // handle error
}
pMasterVolume->Enable();
pMasterVolume->RegisterNotificationSink( MasterVolumeChanged, dwAnyUserValue );
...
pMasterVolume->SetCurrentVolume( dwVolumeToSet );
...
DWORD dwCurrentVolume = pMasterVolume->SetCurrentVolume();
...
void CALLBACK MasterVolumeChanged( DWORD dwCurrentVolume, DWORD dwUserValue )
{
   // handle the volume change
}
...

Very simple, isn't it? Yet, the CVolumeInXXX class requires more explanation. In order to manipulate the Input volume, the source line index is to be passed to the constructor. Confused? Please, be not. CVolumeInXXX class provides a static function to enumerate those lines:

bool EnumerateInputLines( PINPUTLINEPROC, DWORD dwUserValue );

This allows you to manipulate the volume of any WaveIn-based lines. Say, you want to manipulate the microphone volume:

...
bool CALLBACK EnumInputLineProc( UINT uLineIndex, 
              MIXERLINE* pLineInfo, DWORD dwUserValue );
...
// Initialization
UINT uMicrophoneLineIndex = (UINT)-1;
if ( !CVolumeInXXX::EnumerateInputLines( EnumInputLineProc, 
                           (DWORD)&uMicrophoneLineIndex ) )
{
   // handle error
}
if ( uMicrophoneLineIndex == (UINT)-1 )
{
        // Error: mic volume'ing is not available.
}
IVolume* pMicrophoneVolume = 
         (IVolume*)new CVolumeInXXX( uMicrophoneLineIndex );
if ( !pMicrophoneVolume || !pMicrophoneVolume->IsAvailable() )
{
   // handle error
}
// Go on and use pMicrophoneVolume to manipulate the volume
...
bool CALLBACK EnumInputLineProc( UINT uLineIndex, 
              MIXERLINE* pLineInfo, DWORD dwUserValue )
{
    if ( pLineInfo->dwComponentType == 
             MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE )
    {
        *((UINT*)dwUserValue) = uLineIndex;
        return false;
    }
    return true;
}
...

Be aware, that for performance reasons it is better to have a single instance of a given class per application. So don't rush to create lots of CVolumeInXXX objects, better share the only one through your code.

Conclusion

The proposed classes do not encapsulate all the abilities exposed by the mixers. However, working with a mixer just to add a pretty simple functionality is quite boring. That's why, as I think, the proposed classes might be of some help to you.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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About the Author

Alex Chmut
Web Developer
Ukraine Ukraine
No Biography provided

Comments and Discussions

 
SuggestionWindows 7 volume control sample PinmemberM A V15-Dec-12 2:05 
QuestionLicense? PinmemberLuisVilla16-Feb-12 5:48 
Hi, Alex- What is the license on this code? Some people I know are looking into distributing it for commercial purposes. Thanks!
AnswerRe: License? PinmemberAlex Chmut16-Feb-12 11:15 
GeneralControlling master volume in Win7 - IAudioEndpointVolume - Working sample code in MSDN Pinmemberkormoe15-Jan-12 6:39 
GeneralVolume Control in Windows7 PinmemberMember 264083617-Aug-10 21:41 
GeneralMaking compatible PinmemberBazKhan18-Jan-09 23:49 
QuestionWindows Vista Anyone??? Pinmember{bill}1-Sep-08 10:41 
AnswerRe: Windows Vista Anyone??? PinmemberSteven Dong9-Nov-08 5:37 
QuestionCallback Function Pinmemberpeene9-Aug-07 6:46 
Questionhow can i control the sound of left and right speaker Pinmemberrajneshmalik1-Aug-07 22:49 
GeneralProblem in 2000 Pinmemberlilesh26-Feb-07 23:56 
QuestionBegginer's question Pinmemberlnenad12-Nov-06 9:12 
QuestionHigh Definition Audio PinmemberSaber00119-Jul-06 1:09 
QuestionHow to use Volume Manipulation Classes Pinmembercastlezhen28-Apr-06 4:04 
GeneralDiable Microphone Pinmemberanakia18-Apr-06 18:05 
General[Q] Love your article and more... Pinmemberyoontet17-Aug-05 6:52 
GeneralRe: [Q] Love your article and more... Pinmemberyoontet17-Aug-05 7:23 
GeneralProblems with Microphone control PinmemberVirendra Sharma26-May-05 0:29 
GeneralRe: Problems with Microphone control PinmemberFco Javier Lama4-May-06 0:24 
Generaldoesn t work with a USB headset Pinmemberbartouze22-Apr-05 4:09 
GeneralProblem passing callback function in... Pinmemberel davo4-Mar-04 14:48 
GeneralRe: Problem passing callback function in... Pinmemberladuran27-Aug-04 13:55 
GeneralRe: Problem passing callback function in... PinmemberVinod Vijayan29-Jan-05 1:06 
QuestionHow to determine whether volume is enabled? PinmemberM A V22-Feb-04 10:54 
GeneralMany Compile Errors - microphone implementation PinmemberBobboots12-Feb-04 20:19 

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