/*

* Copyright (c) 2007-2009 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 MAUDIOSTREAM_H

#define MAUDIOSTREAM_H

#include <e32base.h>

#include <f32file.h>

#include <mmf/common/mmfcontroller.h>

#include <a3f/a3fbase.h>

class MAudioStreamObserver;

class MAudioCodecObserver;

class MAudioCodec;

class MAudioProcessingUnit;

/**

 * this is the main control interface for the state of a processing unit chain.

 *

 * An AudioStream object binds together audio components processing the same data.

 * An AudioStrem executes the audio processing states as requested by the client. The processing units

 * attached to a stream will follow the state of the stream.

 *

 * The possible states of an AudioStream object are:

 * EUninitialized: The state which the chain is in initially. 

 *		  The logical chain can be constructed.  

 *		  The settings in the logical chain cannot be related to the adaptation because no adaptation has been selected yet. 

 *

 * EInitialized: this state is set after a successful initialization request.

 * EIdle: All the chain resources are allocated, however, no processing time 

 *		(other than expended to put the chain into EIdle state) is consumed in this phase.

 * EPrimed: As per EIdle, but the stream can consume processing time, by filling its buffers.  

 * EActive: The chain has all the resources as per EIdle and EPrimed but also has started to 

 *	   process the actions requested by the client.  

 * EDead:   The stream can no longer function due to fatal error.

 *	   The logical chain still exists, but any physical resources should be reclaimed by the adaptation. 

 *

 * The MAudioStreamObserver includes completion callbacks for many of the methods of MAudioStream.

 * The protocol is such that when an asynchronous method is called and KErrNone is returned,

 * then the call will be followed by a corresponding callback. if the returned error code from

 * the asynchronous function is other than KErrNone, then a callback will not be made as

 * a result of that method call. The callbacks will always occur out-of-context.

 * Note that many of the functions will also require a context commit for the actual processing to take place. 

 */

class MAudioStream 

	{

public:

	/**

	 * Registers an audio stream observer.

	 *

	 * Note that this function is meant for clients of the Audio Stream. 

	 * The client should unregister using UnregisterAudioStreamObserver() when applicable.

	 *

	 * @param aObserver reference to the observer to register.

	 * @return an error code. KErrNone if successful.

	 *			  			  KErrAlreadyExists if the client is already registered.

	 *						  KErrOutOfMemory in case of memory exhaustion.

	 */

	virtual TInt RegisterAudioStreamObserver(MAudioStreamObserver& aObserver)=0;

	/**

	 * Unregisters an audio stream observer.

	 *

	 * @param aObserver reference to the observer to unregister.

	 * @return an error code.  KErrNone if successful. KErrNotFound if the client has not been registered as observer.

	 */

	virtual void UnregisterAudioStreamObserver(MAudioStreamObserver& aObserver)=0;

	/**

	 * Sets the type of audio being processed in this context.

	 *

	 * The audio type settings are used by the resource control subsystem when it arbitrates between multiple clients 

	 * trying to access the same resource. Additionally it may impact the availability of certain audio features for the client. 

	 * It may also have an effect on other aspects, including, but not limited to routing and automatically applied effects. 

	 * The audio types available for the client may be limited by the platform security capabilities, vendorId etc of the client application.

	 *

	 * @param aAudioTypeSettings defines the settings associated with this stream.

	 * @return an error code. KErrNone if successful, otherwise one of the system wide error codes.

	 */

	virtual TInt SetAudioType(const TAudioTypeSettings& aAudioTypeSettings)=0;

	/**

	 * Fetch the type of audio being processed in this stream.

	 *

	 * @param aAudioTypeSettings On return contains the audio type of this stream.

	 */

	virtual void GetAudioType(TAudioTypeSettings& aAudioTypeSettings) const = 0;

	/**

	 * Requests a transition to the EInitialized state. 

	 *

	 * this function is asynchronous, and its successful return merely issues a request which is acted upon on Commit(), 

	 * and while will lead to a StateEvent() callback. this function is only allowed while the stream is in EUninitialized state. 

	 * A call in any other state will cause an error code of KErrNotReady to be returned.

	 *

	 * @return an error code. if KErrNone, the state transition has been requested, 

	 * and there will be a StateEvent() callback following Commit(). 

	 * On error, there is no request made: KErrNotReady states the stream if not in valid current state, 

	 * otherwise one of the system-wide error codes.

	*/

	virtual TInt Initialize()=0;

	/**

	 * Requests a transition to the EIdle state. 

	 *

	 * this function is asynchronous, and its successful return merely issues a request which is acted upon on Commit(), 

	 * and while will lead to a StateEvent() callback. this function is only allowed while the stream is in EInitialized state. 

	 * A call in any other state will cause an error code of KErrNotReady to be returned

	 *

	 * The resources must be released using Unload() when they are no longer needed. 

	 * Note that it is recommended that the resources are not kept reserved for long periods of inactivity, 

	 * since it may prevent other audio streams from becoming active by stealing resources they need to use

	 *

	 * @return An error code. if KErrNone, the state transition has been requested, 

	 * and there will be a StateEvent() callback following Commit(). 

	 * On error, there is no request made: KErrNotReady states the stream if not in valid current state, 

	 * otherwise one of the system-wide error codes.

	 */

	virtual TInt Load()=0;

	/**

	 * Starts the audio processing. this function is only allowed while the stream is in EIdle or EPrimed states. 

	 *

	 * The start-up procedures include requesting permission for audio processing from audio policy. 

	 *

	 * @return an error code. A call in any state different to EIdle or EPrimed will cause an error code of KErrNotReady.

	 * if permission to start is denied by audio policy, a state change back to EPrimed will occur with error code KErrAccessDenied

	*/

	virtual TInt Activate()=0;

	/**

	 * Requests a transition to the Idle state – stopping the ongoing operation. 

	 *

	 * this function is asynchronous, and its successful return merely issues a request which is acted upon on Commit(), 

	 * and while will lead to a StateEvent() callback this function is only allowed while the stream is either Active or Primed. 

	 * A call in any other state will cause an error code of KErrNotReady to be returned. 	

	 * @return An error code. if KErrNone, the state transition has been requested, and there will be a StateEvent() callback 

	 * following Commit(). On error, there is no request made: KErrNotReady states the stream if not in valid current state, 

	 * otherwise one of the system-wide error codes

	*/

	virtual TInt Stop()=0;

	/**

	 * Prepares the audio stream for releasing the resources reserved for it and for the processing units attached to the stream.

	 *

 	 * this function is only allowed while the stream is EIdle state.

	 * A call in any other state will cause an error code of KErrNotReady to be returned.

	 *

	 * During this call the stream will query all attached processing units whether they are ready to unload.

	 * if a processing unit indicates that it is not ready to uninitialize, then an error code other than KErrNone will be returned.

	 * Provided that this call succeeds, the actual unloading process will begins once Commit() is called for the context of this stream.

	 *

	 * @return An error code. KErrNone if successful.

	 *			  KErrNotReady if called while the stream is not in correct state.

	 *			  Other system wide error codes are also possible.

	 */

	virtual TInt Unload()=0;

	/**

	 * Requests a transition to the Unitialized state – returning the stream to its initial state.

	 *

	 * this function is asynchronous, and its successful return merely issues a request which is acted upon on Commit(), 

	 * and while will lead to a StateEvent() callback. this function is only allowed while the stream is in Initialized state. 

	 * A call in any other state will cause an error code of KErrNotReady to be returned.

	 *

	 * @return an error code. if KErrNone, the state transition has been requested, and there will be a StateEvent() callback 

	 * following Commit(). On error, there is no request made: KErrNotReady states the stream if not in valid current state, 

	 * otherwise one of the system-wide error codes.

	 */

	virtual TInt Uninitialize()=0;

	/**

	 * Requests a transition to the EPrime state. 

	 * 

	 * this function is asynchronous, and its successful return merely issues a request which is acted upon on Commit(), 

	 * and while will lead to a StateEvent() callback. this function is only allowed while the stream is in EActive 

	 * (semantics of Prime in EActive– go into a buffering pause) or EIdle state (semantics of Prime in EIdle – start to buffer). 

	 * A call in any other state will cause an error code of KErrNotReady to be returned.  Not all streams support Prime.

	 *

	 * @return an error code. if KErrNone, the state transition has been requested, and there will be a StateEvent() callback 

	 * following Commit(). On error, there is no request made: KErrNotReady states the stream if not in valid current state, 

	 * otherwise one of the system-wide error codes

	 */

	virtual TInt Prime()=0;

	/**

	 * Empty any buffers that have been filled. 

	 *

	 * Reclain any outstanding buffers from the client, if required. 

	 * this function is only allowed while the stream is in Idle state. this is an asynchronous operation. 

	 * if the call returns KErrNone it merely indicates a flush has been requested and there will be a subsequent FlushComplete() callback. 

	 * Note that this does not relate to the Commit() cycle, and is not considered transactional.

	 *

	 * @return a system wide error code. KErrNone if successful.

	 * KErrNotReady if called while the stream is not in correct state. Other system wide error codes are also possible.

	 */

	virtual TInt Flush()=0;

	/**

	 * Adds an audio source to this stream.

	 *

	 * A stream cannot operate before a source has been set.

	 * The source must be removed from the stream before the sink or the stream is destroyed.

	 * The source can only be set while the stream is in uninitialized state.

	 * this is an asynchronous call and the completion will be indicated to the

	 * client via a callback in the stream observer interface.

 	 *

	 * @param aSource the audio source for this stream.

	 * @return an error code. KErrNone if successful, there will be a subsequent callback on MAudioStreamObserver::AddProcessingUnitComplete().

	 * 			KErrInUse a source has already been set fot this stream.

	 *		 	KErrNotReady the stream is not in correct state.

	 */ 

	virtual TInt AddSource(MAudioProcessingUnit* aSource)=0;

	/**

	 * Adds sink for this stream.

	 *

	 * Stream cannot operate before source and sink have been set.	

	 * The sink must be removed from the stream before it is destroyed.

 	 * The sink can only be set while the stream is in uninitialized state.

	 * this is an asynchronous call and the completion will be indicated to the

	 * client via a callback in the stream observer interface.

	 *

	 * @param aSink the sink for this stream

	 * @return an error code. KErrNone if successful, there will be a subsequent callback on MAudioStreamObserver::AddProcessingUnitComplete().

	 * 		          		  KErrInUse a sink has already been set fot this stream.

	 *				  	  KErrNotReady the stream is not in correct state,

	*/

	virtual TInt AddSink(MAudioProcessingUnit* aSink)=0;

	/**

	 * Adds an codec for this stream.

	 *

	 * The codec must be removed from the stream before the codec or the stream

	 * is deleted. The codec can only be set while the stream is in uninitialized state.

	 * this is an asynchronous call and the completion will be indicated to

	 * the client via a callback in the stream observer interface.

	 *

	 * @param aCodec the codec for this stream

	 * @return an error code. KErrNone if successful, there will be a subsequent callback on MAudioStreamObserver::AddProcessingUnitComplete().

	 *		         		  KErrInUse a codec has already been set fot this stream.

	 *               		  KErrNotReady the stream is not in correct state.

	 */

	virtual TInt AddAudioCodec(MAudioProcessingUnit* aCodec)=0;

	/**

	 * Adds an audio processing unit to this stream. 

	 *

	 * The processing unit must be removed from the stream before the processing unit or the stream is removed from the context. 

	 * The supplied component must implement the AudioGainControl feature. 

	 * 

	 * @param aGainControl  the gain control to add to this stream.

	 * @return KErrNone if succesful returned, there will be a subsequent callback on MAudioStreamObserver::AddProcessingUnitComplete().

	 *	       KErrInUse a gain control has already been set fot this stream.

	 *	       KErrNotReady the stream is not in correct state.

	 */

	virtual TInt AddGainControl(MAudioProcessingUnit* aGainControl)=0;

	/**

	 * Removes any audio processing unit from this stream, whether it has been added by AddSource(), AddSink(), AddCodec() or AddGainControl().

	 * this is an asynchronous function, on successful call there will be a subsequent RemoveProcessingUnitComplete() callback.

	 * @param aProcessingUnit  the processing unit to remove.

	 * @return a system wide error code, KErrNone if successful, or the processing unit had not been added to the stream. 

	 * KErrNotReady the decoder is not in correct state. Other system wide error codes are also possible. 

	 */

	virtual TInt RemoveProcessingUnit(MAudioProcessingUnit* aProcessingUnit)=0;

	/**

	 * Resets the duration counter. 

	 *

	 * Used to differentiate between when a stream has been momentarily interrupted and when 

	 * a different conceptual use-case is underway.  Defined for EIdle.

	 */

	virtual TInt ResetStreamTime()=0;

	/**

	 * Returns the duration of audio that has been processed from the hardware device perspective. 

	 * The time is reset when the MAudioStream object transfers from Initialized state to Idle. 

	 * as a result of calling Load(). It can be reset at other times using ResetStreamTime().

	 */

	virtual TInt GetStreamTime(TTimeIntervalMicroSeconds& aStreamTime)=0;

	/**

	 * A mechanism to obtain additional control APIs on the stream.  

	 *

	 * These can be used to extend the basic play/record, pause, stop with future use-cases such as seek play.	

	 *

	 * @param aType Uid that denotes the type of the interface.

	 * @return the pointer to the specified interface, or NULL if it does not exist. Must be cast to correct type by the user..

	 */

	virtual TAny* Interface(TUid aType)=0;

	/**

	 * Returns the component instance id.

	 *

	 * @return component instance id.

	 */

	virtual TAudioStreamId InstanceId() const =0;

	};

#endif // MAUDIOSTREAM_H