only show level meters if the server actually supports it and sends network packets with levels to the client

src/audiomixerboard.cpp

@@ -193,6 +193,11 @@ void CChannelFader::SetDisplayChannelLevel ( const bool eNDCL )
     plbrChannelLevel->setHidden ( !eNDCL );
 }
 
+bool CChannelFader::GetDisplayChannelLevel()
+{
+    return !plbrChannelLevel->isHidden();
+}
+
 void CChannelFader::SetupFaderTag ( const ESkillLevel eSkillLevel )
 {
     // setup group box for label/instrument picture: set a thick black border
@@ -678,10 +683,15 @@ void CAudioMixerBoard::SetDisplayChannelLevels ( const bool eNDCL )
 {
     bDisplayChannelLevels = eNDCL;
 
-    // apply preference to child GUI controls
+    // only update hiding the levels immediately, showing the levels
+    // is only applied if the server actually transmits levels
+    if ( !bDisplayChannelLevels )
+    {
+        // hide all level meters
         for ( int i = 0; i < MAX_NUM_CHANNELS; i++ )
         {
-        vecpChanFader[i]->SetDisplayChannelLevel ( bDisplayChannelLevels );
+            vecpChanFader[i]->SetDisplayChannelLevel ( false );
+        }
     }
 }
 
@@ -693,6 +703,7 @@ void CAudioMixerBoard::HideAll()
         // before hiding the fader, store its level (if some conditions are fullfilled)
         StoreFaderSettings ( vecpChanFader[i] );
 
+        vecpChanFader[i]->SetDisplayChannelLevel ( false );
         vecpChanFader[i]->Hide();
     }
 
@@ -922,6 +933,13 @@ void CAudioMixerBoard::SetChannelLevels ( const CVector<uint16_t>& vecChannelLev
         if ( vecpChanFader[iChId]->IsVisible() && i < iNumChannelLevels )
         {
             vecpChanFader[iChId]->SetChannelLevel ( vecChannelLevel[i++] );
+
+            // show level only if we successfully received levels from the
+            // server (if server does not support levels, do not show levels)
+            if ( bDisplayChannelLevels && !vecpChanFader[iChId]->GetDisplayChannelLevel() )
+            {
+                vecpChanFader[iChId]->SetDisplayChannelLevel ( true );
+            }
         }
     }
 }

src/audiomixerboard.h

@@ -57,6 +57,7 @@ public:
     bool IsMute() { return pcbMute->isChecked(); }
     void SetGUIDesign ( const EGUIDesign eNewDesign );
     void SetDisplayChannelLevel ( const bool eNDCL );
+    bool GetDisplayChannelLevel();
 
     void UpdateSoloState ( const bool bNewOtherSoloState );
     void SetFaderLevel ( const int iLevel );