diff -r 000000000000 -r bde4ae8d615e os/mm/devsound/a3facf/inc/maudiogaincontrolobserver.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/os/mm/devsound/a3facf/inc/maudiogaincontrolobserver.h	Fri Jun 15 03:10:57 2012 +0200
@@ -0,0 +1,87 @@
+/*
+* Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
+* All rights reserved.
+* This component and the accompanying materials are made available
+* under the terms of "Eclipse Public License v1.0"
+* which accompanies this distribution, and is available
+* at the URL "http://www.eclipse.org/legal/epl-v10.html".
+*
+* Initial Contributors:
+* Nokia Corporation - initial contribution.
+*
+* Contributors:
+*
+* Description:
+*
+*/
+
+
+
+
+/**
+ @file
+ @publishedPartner
+ @released
+*/
+
+#ifndef MAUDIOGAINCONTROLOBSERVER_H
+#define MAUDIOGAINCONTROLOBSERVER_H
+
+#include <e32base.h>
+#include <a3f/a3fbase.h>
+#include <a3f/maudiogaincontrol.h>
+
+/**
+ *  An interface to a set of AudioGainControl callback functions.
+ *
+ *  this serves as the method of communication between the client and the
+ *  AudioGainControl.
+ *
+ *  The class is a mixin and is intended to be inherited by the client class
+ *  that is interested in observing the Gain operations. The functions
+ *  encapsulated by this class are called when specific events occur while
+ *  processing audio.
+ *
+ */
+class MAudioGainControlObserver
+	{
+public:
+
+	/**
+	* Notifies the observer that the max ramp time supported by the gain
+	* control has changed.
+	*
+	* @param aGain a reference to GainControl whose max ramp time changed.
+	*/
+	virtual void MaxRampTimeChanged(MAudioGainControl& aGain)=0;
+
+	/**
+	* Notifies the observer that the maximum gain value supported by the
+	* gain control has changed.
+	*
+	* @param aGain a reference to GainControl whose max gain changed.
+	*/
+	virtual void MaxGainChanged(MAudioGainControl& aGain)=0;
+
+	/**
+	* Notifies the observer that the gain has changed, 
+	* due to request from the client or otherwise.  
+	* If gain change by the client cannot be fulfilled, 
+	* a gain change with an error code other than KErrNone will be issued.
+	* @param aGain	a reference to the gain control whose gain has changed.
+	* @return aError		an error code. 
+	* KErrNone if the gain change was requested by the client and was completed successfully.
+	* KErrNotSupported if the SetGain() call referred to non-existent channels.
+	* KErrArgument if aGain of less than 0 or larger than max gain, 
+	* the same channel is specified multiple times, 
+	* or aRampDuration is less than 0 or greater than max ramp duration.
+	* KErrA3fUnsupportedRamp if the ramp operation requested is not supported, 
+	* or the Uid value supplies is unknown.
+	* Other system-wide errors are also possible. They will indicate that the gain change failed.
+	* Note that these errors could alternatively be returned by the associated SetGain() call.
+	*/
+	virtual void GainChanged(MAudioGainControl& aGain, TInt aError)=0;
+
+	};
+
+#endif // MAUDIOGAINCONTROLOBSERVER_H