From Brad Christiansen, "I have added an implementation for set/getVolume in the direct show plug-in."

src/osgPlugins/directshow/DirectShowTexture

@@ -65,6 +65,8 @@ public:
     double getTimeMultiplier() const;
     void quit(bool /*waitForThreadToExit*/ = true);
     void stop();
+    void setVolume(float);
+    float getVolume() const;
 };
 
 
@@ -76,8 +78,9 @@ class CTextureRenderer : public CBaseVideoRenderer, public osg::Referenced
 public:
     IGraphBuilder*  _graphBuilder;          // GraphBuilder
     IMediaControl*  _mediaControl;          // Media Control
-    IMediaSeeking*    _mediaSeeking;          // Media seeking
+    IMediaSeeking*  _mediaSeeking;          // Media seeking
     IMediaEvent*    _mediaEvent;          // Media Event
+    IBasicAudio*    _basicAudio;
     IBaseFilter*    _videoCaptureDevice;
     IBaseFilter*    _fileSource;
     IBaseFilter*    _soundOutputDevice;

src/osgPlugins/directshow/DirectShowTexture.cpp

@@ -806,6 +806,11 @@ bool CTextureRenderer::initBuildGraph()
     hr = _graphBuilder->AddFilter((IBaseFilter*)this, L"Sampler");
     if (!checkError(prefixForMessage, hr))
         return false;
+
+
+    hr = _graphBuilder->QueryInterface( IID_IBasicAudio, (void **)&_basicAudio);
+    checkError(prefixForMessage, hr); //May be no sound so dont effect return result
+    
     return true;
 }
 
@@ -1104,6 +1109,7 @@ bool CTextureRenderer::setupOutputSoundDevice(ICreateDevEnum* devs)
         if (_soundOutputDevice) _soundOutputDevice->Release(); _soundOutputDevice = 0;
         return false;
     }
+
     return true;
 }
 
@@ -1545,6 +1551,7 @@ void CTextureRenderer::releaseRessources()
     if (_mediaControl) _mediaControl->Release(); _mediaControl = 0;
     if (_mediaEvent) _mediaEvent->Release(); _mediaEvent = 0;
     if (_mediaSeeking) _mediaSeeking->Release(); _mediaSeeking = 0;
+    if (_basicAudio) _basicAudio->Release(); _basicAudio = 0;
     // remove filter outside because this is a filter too.
 }
 
@@ -1578,6 +1585,7 @@ CTextureRenderer::CTextureRenderer( DirectShowImageStream* is, HRESULT* valid)
     _videoCaptureDevice = 0;
     _soundOutputDevice = 0;
     _soundCaptureDevice = 0;
+    _basicAudio = 0;
 }
 
 
@@ -1882,6 +1890,26 @@ double DirectShowImageStream::getTimeMultiplier() const
     return rate; 
 }
 
+void DirectShowImageStream::setVolume(float vol) {  
+   OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);    
+   if (_renderer.valid() && _renderer->_basicAudio) 
+   {    
+     _renderer->_basicAudio->put_Volume(vol);     
+   }   
+}
+
+float DirectShowImageStream::getVolume() const {
+  OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);      
+  double vol = 0;  
+  if (_renderer.valid() && _renderer->_basicAudio) 
+  {   
+    long d = 0;
+    _renderer->_basicAudio->get_Volume(&d);    
+    vol = static_cast<double>(d);    
+  }    
+  return vol;
+}
+
 void DirectShowImageStream::stop()
 {
     OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);