--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/devsound/a3facf/inc/maudiostreamobserver.h	Tue Feb 02 01:56:55 2010 +0200
@@ -0,0 +1,103 @@
+/*
+* 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 MAUDIOSTREAMOBSERVER_H
+#define MAUDIOSTREAMOBSERVER_H
+
+#include <e32base.h>
+#include <a3f/a3fbase.h>
+#include <a3f/maudiostream.h>
+
+/**
+ * An interface to a set of AudioStream callback functions.
+ *
+ * this serves as the method of communication between the client and the
+ * AudioStream.
+ *
+ * The class is a mixin and is intended to be inherited by the client class
+ * that is interested in observing the AudioStream operation. The functions
+ * encapsulated by this class are called when specific events occur while
+ * processing audio.
+ */
+class MAudioStreamObserver
+	{
+public:
+	/**
+	 * Handles audio stream state change event.
+	 *
+	 * @param aStream A reference to the stream whose state changed.
+	 * @param aReason A set of values describing why the state change occurred 
+	 * corresponding to the system-wide error codes. The value will be KErrNone on successful calls.
+	 * @param aNewState indicating the state in which the audio stream has changed.
+	 */
+	virtual void StateEvent(MAudioStream& aStream , TInt aReason, TAudioState aNewState)=0;
+
+	/**
+	 * Notifies that adding of processing unit to the stream has been completed successfully or otherwise.
+	 *
+	 * if the processing unit is added succesfully, then it must be removed from the
+	 * stream before the processing unit is removed from the context or before the stream is removed.
+	 *
+	 * @param aStream A reference to the stream to which the processing unit was added.
+	 * @param aInstance a pointer to the processing unit instance.
+	 * @param aError an error code. KErrNone on success. Otherwise one of the system wide error codes.
+	 */
+	virtual void AddProcessingUnitComplete(MAudioStream& aStream, MAudioProcessingUnit* aInstance, TInt aError)=0;
+
+	/**
+	 * Notifies that removing of processing unit from the stream has been completed
+	 * successfully or otherwise.
+	 * 
+	 * if the processing unit has been added succesfully, then it must be removed
+	 * from the stream, before the processing unit is removed from the
+	 * context or before the stream is removed.
+	 * 
+	 * @param aStream A reference to the stream from which the processing unit has been removed.
+	 * @param aType the processing unit type.
+	 * @param aInstance a pointer to the processing unit instance.
+	 * @param aError an error code. KErrNone on success. Otherwise one of the system wide error codes.
+	 */
+	virtual void RemoveProcessingUnitComplete(MAudioStream& aStream, MAudioProcessingUnit* aInstance, TInt aError)=0;
+
+	/**
+	 * Call-back indicating that is the last buffer has been processed by the sink.
+	 *
+	 * @param aStream A reference to the stream.
+	 */
+	virtual void ProcessingFinished (MAudioStream& aStream)=0;
+
+	/**
+	 * Signals completion of a Flush() operation.
+	 *
+	 * @param aStream A reference to the stream on which Flush() was called.  
+	 * @param aError an error code. KErrAbort if the associated stream has been unloaded, and the buffers cease to exist.
+	 */
+	virtual void FlushComplete (MAudioStream& aStream, TInt aError) = 0;
+
+	};
+
+#endif // MAUDIOSTREAMOBSERVER_H