tetrees/Plugins/Wwise/ThirdParty/include/AK/SoundEngine/Common/AkStreamMgrModule.h

/*******************************************************************************
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  Copyright (c) 2023 Audiokinetic Inc.
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/// \file 
/// Audiokinetic's implementation-specific definitions and factory of 
/// overridable Stream Manager module.
/// Contains the default Stream Manager's implementation-specific interfaces that altogether constitute
/// the Low-Level I/O submodule. This submodule needs to be implemented by the game. All I/O requests 
/// generated by the Stream Manager end up to one of the I/O hooks defined herein.
/// Read \ref streamingmanager_lowlevel to learn more about the Low-Level I/O.

#ifndef _AK_STREAM_MGR_MODULE_H_
#define _AK_STREAM_MGR_MODULE_H_

#include <AK/SoundEngine/Common/IAkStreamMgr.h>
#include <AK/Tools/Common/AkPlatformFuncs.h>

/// \name Audiokinetic Stream Manager's implementation-specific definitions.
//@{
/// Stream Manager initialization settings.
/// \sa 
/// - AK::IAkStreamMgr
/// - AK::StreamMgr::Create()
/// - \ref streamingmanager_settings

struct AkStreamMgrSettings
{
};

/// High-level IO devices initialization settings.
/// \sa 
/// - AK::IAkStreamMgr
/// - AK::StreamMgr::CreateDevice()
/// - \ref streamingmanager_settings
struct AkDeviceSettings
{
	void *				pIOMemory;					///< Pointer for I/O memory allocated by user.
													///< Pass NULL if you want memory to be allocated via AK::MemoryMgr::Malign().
													///< If specified, uIOMemorySize, uIOMemoryAlignment and ePoolAttributes are ignored.
	AkUInt32			uIOMemorySize;				///< Size of memory for I/O (for automatic streams). It is passed directly to AK::MemoryMgr::Malign(), after having been rounded down to a multiple of uGranularity.
	AkUInt32			uIOMemoryAlignment;			///< I/O memory alignment. It is passed directly to AK::MemoryMgr::Malign().
	AkUInt32			ePoolAttributes;			///< Attributes for I/O memory. Here, specify the allocation type (AkMemType_Device, and so on). It is passed directly to AK::MemoryMgr::Malign().
	AkUInt32			uGranularity;				///< I/O requests granularity (typical bytes/request).
    AkThreadProperties	threadProperties;			///< Scheduler thread properties.
	AkReal32			fTargetAutoStmBufferLength;	///< Targetted automatic stream buffer length (ms). When a stream reaches that buffering, it stops being scheduled for I/O except if the scheduler is idle.
	AkUInt32			uMaxConcurrentIO;			///< Maximum number of transfers that can be sent simultaneously to the Low-Level I/O.
	bool				bUseStreamCache;			///< If true, the device attempts to reuse I/O buffers that have already been streamed from disk. This is particularly useful when streaming small looping sounds. However, there is a small increase in CPU usage when allocating memory, and a slightly larger memory footprint in the StreamManager pool. 													
	AkUInt32			uMaxCachePinnedBytes;		///< Maximum number of bytes that can be "pinned" using AK::SoundEngine::PinEventInStreamCache() or AK::IAkStreamMgr::PinFileInCache()
};

/// File descriptor. File identification for the low-level I/O.
/// \sa
/// - AK::StreamMgr::IAkLowLevelIOHook
/// - AK::StreamMgr::IAkLowLevelIOHook::BatchOpen
/// - AK::StreamMgr::IAkLowLevelIOHook::Close
struct AkFileDesc
{
    AkInt64				iFileSize  = 0;			///< File size in bytes
    AkUInt64			uSector = 0;			///< Start sector (the sector size is specified by the low-level I/O)
												///< \sa
												///< - AK::StreamMgr::IAkFileLocationResolver::Open()
												///< - AK::StreamMgr::IAkLowLevelIOHook::GetBlockSize()
    AkFileHandle		hFile = AkFileHandle(); ///< File handle/identifier
    AkDeviceID			deviceID = AK_INVALID_DEVICE_ID;			///< Device ID, obtained from CreateDevice() \sa AK::IAkStreamMgr::CreateDevice()
};

/// Structure for synchronous transfers handshaking with the Low-Level I/O. Used with blocking I/O hooks.
/// \sa AK::StreamMgr::IAkLowLevelIOHook
struct AkIOTransferInfo
{
	AkUInt64		uFilePosition;		///< File offset where transfer should begin.
    AkUInt32		uBufferSize;		///< Size of the buffer in which the I/O hook can write to.
	AkUInt32		uRequestedSize;		///< Exact number of requested bytes for this transfer. Always equal to or smaller than uBufferSize.
};

struct AkAsyncIOTransferInfo;

/// Callback function prototype definition used for asynchronous I/O transfers between the Stream Manager and the Low-Level IO.
/// Notes:
/// - If you pass in_eResult of AK_Fail, all streams awaiting for this transfer are marked as invalid and will stop. An "IO error" notification is posted to the capture log.
/// - If the transfer was cancelled by the Stream Manager while it was in the Low-Level IO, you must return AK_Success, whether
/// you performed the operation or not. The Stream Manager knows that it was cancelled, so it will not try to use it after you call it back.
/// \sa 
/// - AkAsyncIOTransferInfo
/// - AK::StreamMgr::IAkLowLevelIOHook
AK_CALLBACK( void, AkIOCallback )( 
	AkAsyncIOTransferInfo * in_pTransferInfo,	///< Pointer to the AkAsyncIOTransferInfo structure that was passed to corresponding Read() or Write() call.
	AKRESULT		in_eResult					///< Result of transfer: AK_Success or AK_Fail (streams waiting for this transfer become invalid).
	);

/// Structure for asynchronous transfers handshaking with the Low-Level I/O. Extends AkIOTransferInfo.
/// \sa 
/// - AK::StreamMgr::IAkLowLevelIOHook
/// - AkIOTransferInfo
/// - AkAIOCallback
struct AkAsyncIOTransferInfo : public AkIOTransferInfo
{
	void *			pBuffer;			///< Buffer for data transfer.
	AkIOCallback	pCallback;			///< Callback function used to notify the high-level device when the transfer is complete.
	void *			pCookie;			///< Reserved. The I/O device uses this cookie to retrieve the owner of the transfer.
	void *			pUserData;			///< Custom user data.	
};

struct AkAsyncFileOpenData;

/// Callback signature for the notification of completion of the asynchronous Open operation.
/// \sa 
/// - AkAsyncFileOpenData
/// - AK::StreamMgr::IAkLowLevelIOHook::BatchOpen
AK_CALLBACK(void, AkFileOpenCallback)(
	AkAsyncFileOpenData * in_pOpenInfo,	///< Pointer to the AkAsyncFileOpenData structure that was passed to corresponding Open().
	AKRESULT			in_eResult			///< Result of transfer: AK_Success or AK_Fail (streams waiting for this transfer become invalid).
	);

/// Structure used by Low Level IO Hooks (IAkLowLevelIOHook) to pass and retreive information on files to be opened by the IO hook.
/// Please refer to AK::StreamMgr::IAkLowLevelIOHook::BatchOpen for more information about the sementics of the Open operation.
/// \sa 
/// - AkFileOpenData
/// - AK::StreamMgr::IAkLowLevelIOHook::BatchOpen
struct AkAsyncFileOpenData : public AkFileOpenData
{
	~AkAsyncFileOpenData();

	AkAsyncFileOpenData(const AkFileOpenData& in_copy)
		: pCallback(NULL)
		, pCookie(NULL)
		, pFileDesc(NULL)
		, pCustomData(NULL)
		, pszStreamName(NULL)
	{
		*(AkFileOpenData*)this = in_copy;
	}

	AkAsyncFileOpenData(const AkAsyncFileOpenData& in_copy)
		: pCallback(in_copy.pCallback)
		, pCookie(in_copy.pCookie)
		, pFileDesc(in_copy.pFileDesc)
		, pCustomData(NULL)
		, pszStreamName(NULL)
	{
		*(AkFileOpenData*)this = in_copy;
	}

	AkAsyncFileOpenData() 
		: AkFileOpenData()
		, pCallback(NULL)
		, pCookie(NULL)
		, pFileDesc(NULL)
		, pCustomData(NULL)
		, pszStreamName(NULL)
	{}
		
	AkAsyncFileOpenData(const AkOSChar* in_pszFileName, AkOpenMode in_eOpenMode = AK_OpenModeRead, AkFileSystemFlags* in_pFlags = NULL)
		:AkFileOpenData(in_pszFileName, in_eOpenMode, in_pFlags)
		, pCallback(NULL)
		, pCookie(NULL)
		, pFileDesc(NULL)
		, pCustomData(NULL)
		, pszStreamName(NULL)
	{}

	AkAsyncFileOpenData(AkFileID in_idFile, AkOpenMode in_eOpenMode = AK_OpenModeRead, AkFileSystemFlags* in_pFlags = NULL)
		:AkFileOpenData(in_idFile, in_eOpenMode, in_pFlags)
		, pCallback(NULL)
		, pCookie(NULL)
		, pFileDesc(NULL)
		, pCustomData(NULL)
		, pszStreamName(NULL)
	{}

	///< Functions used to manage optional stream name. The name will be used when sending stream information to the Wwise profiler.
	AKRESULT SetStreamName(const AkOSChar* in_pszStreamName);
	const AkOSChar* GetStreamName() const { return pszStreamName; }

	AkFileOpenCallback	pCallback;			///< Callback function used to notify the high-level device when Open is done
	void*				pCookie;			///< Reserved. Pass this unchanged to the callback function. The I/O device uses this cookie to retrieve the owner of the transfer.
	AkFileDesc*			pFileDesc;			///< File Descriptor to fill once the Open operation is complete. 
	void*				pCustomData;		///< Convienience pointer for the IO hook implementer. Useful for additional data used in asynchronous implementations, for example.

private:
	AkOSChar*		pszStreamName;		///< Display name. If provided, this will be used to set the stream name, which is used for the profiler. This struct is not responsible for the memory.
};

/// Low-Level I/O requests heuristics.
/// Used for asynchronous read requests. 
/// \sa 
/// - AK::StreamMgr::IAkLowLevelIOHook::BatchRead()
/// - AK::StreamMgr::IAkLowLevelIOHook::BatchWrite()
struct AkIoHeuristics
{
	AkReal32		fDeadline;			///< Operation deadline (ms). 
	AkPriority		priority;			///< Operation priority (at the time it was scheduled and sent to the Low-Level I/O). Range is [AK_MIN_PRIORITY,AK_MAX_PRIORITY], inclusively.
};


//@}

namespace AK
{
	/// Audiokinetic Stream Manager's implementation-specific interfaces of the Low-Level IO submodule.
	namespace StreamMgr
	{
		/// Interface for batched deferred low-level I/O transfers.
		/// This I/O transfer handshaking method is preferred when you want to hook I/O to your own
		/// I/O streaming technology, and you want to submit multiple I/O requests in one call, so as
		/// to allow for better opportunities for CPU and I/O performance.
		/// All operations in this interface will be happening in the device's own thread, separate
		/// from the main audio thread. Also, it is assumed that all operations are asynchronous although
		/// immediate resolution is also supported.
		/// You may queue them into your own system, and even use the heuristics passed down to this
		/// level for your convenience. Note that the requests are always sent in the order that the
		/// Stream Manager considers to be the most appropriate. You may receive less than
		/// AkDeviceSettings::uMaxConcurrentIO at any given time. The number of concurrent transfers
		/// depends on the number of streams running in the high-level streaming device, and on its
		/// target buffering length and granularity. Your advantage at this level is to be aware of
		/// file placement, so you may try to re-order requests in order to minimize seeking on disk. 
		/// Calls to BatchRead()/BatchWrite() should return as soon as possible. You need to call 
		/// AkAsyncIOTransferInfo::pCallback for all individual items in a transfer batch.
		/// Cancel() is provided in order to inform you that the streaming device will flush this transfer
		/// upon completion. You may implement it or not. In all cases, you must call the callback.
		class IAkLowLevelIOHook
		{
		protected:
			/// Virtual destructor on interface to avoid warnings.
			virtual ~IAkLowLevelIOHook(){}

		public:

			/// Closes a file. 
			/// The file descriptor should be deleted during this call. 
			/// No other module should have a reference to it at this point.
			/// \return AK_Success if the file was properly cleaned-up.
			virtual AKRESULT Close(
				AkFileDesc *			in_pFileDesc			///< File descriptor.
				) = 0;

			/// Returns the block size for the file or its storage device. 
			/// The block size is a constraint for clients
			/// of the Stream Manager: All reads, writes and position changes need to be a multiple of
			/// that size.
			/// \return 
			/// The block size for a specific file or storage device.
			/// \remarks 
			/// - Some files might be opened with flags that require I/O transfers to be a multiple 
			/// of this size. The stream manager will query this function to resolve calls 
			/// to IAk(Auto)Stream::GetBlockSize( ).
			/// - Also, AkFileDesc::uSector specifies a number of sectors in multiples of this value.
			/// - Files/IO devices that do not require byte alignment should return 1.
			///	- Whether file opening was deferred or not, GetBlockSize() is always called right 
			/// after the first call to Open(), in the client's thread, and is never called again.
			/// \warning 
			/// Returning 0 is not allowed and will likely make the Stream Manager crash.
			/// \sa 
			///	- AK::StreamMgr::IAkLowLevelIOHook::BatchOpen()
			/// - AK::StreamMgr::IAkLowLevelIOHook::BatchRead()
			/// - AK::StreamMgr::IAkLowLevelIOHook::BatchWrite()
			virtual AkUInt32 GetBlockSize(
				AkFileDesc &			in_fileDesc			///< File descriptor.
				) = 0;

			/// Returns a description for the streaming device above this low-level hook.
			/// \remarks For profiling purposes only. The Release configuration of the 
			/// Stream Manager never calls it.
			virtual void GetDeviceDesc(
				AkDeviceDesc &			out_deviceDesc      ///< Device description.
				) = 0;

			/// Returns custom profiling data for the streaming device above this low-level hook.
			/// As opposed to GetDeviceDesc(), this is called at every monitoring frame.
			/// You may implement this function in order to display any value you find useful 
			/// in the "Streaming Devices" tab of the Wwise profiler ("Custom Param" column).
			/// \remarks For profiling purposes only. The Release configuration of the 
			/// Stream Manager never calls it.
			/// \return A 32-bit unsigned value to display in the Wwise profiler.
			virtual AkUInt32 GetDeviceData() = 0;

			struct BatchIoTransferItem
			{
				AkFileDesc* pFileDesc;
				AkIoHeuristics ioHeuristics;
				AkAsyncIOTransferInfo* pTransferInfo;
			};


			/// Request to open multiple files (asynchronous). 
			/// \remarks 
			/// - The pCallback within each AkAsyncFileOpenData must be called when completed. 
			/// - It is possible to mix synchronous and asynchronous file opens, as long as all pCallbacks are eventually called.
			/// - When implementing this function, make sure to process all items even if one fails to be dispatched or to open.
			/// - Pointers in in_ppItems will stay valid until pCallback is called to signal the operation result.
			virtual void BatchOpen(
				AkUInt32						in_uNumFiles,			///< Number of transfers to process
				AkAsyncFileOpenData**			in_ppItems 				///< List of files to open. See remarks above.
			) = 0;

			/// Reads multiple data from multiple files (asynchronous).
			/// \remarks 
			/// - Queue up multiple read requests at once, using the provided array of in_pTransferItems. There will
			/// be in_uNumTransfers number of items in the array.
			/// - The pCallback within each BatchIoTransferItem::pTransferInfo must be called when completed.
			/// - The pointer to each BatchIoTransferItem::pTransferInfo will be valid until the high-level
			/// device is notified through the callback. However, the array of in_pTransferItems will not be valid.
			/// - File position passed in each BatchIoTransferItem::pTransferInfo takes the offset of this file relative 
			/// to AkFileDesc::hFile (described with AkFileDesc::uSector). It is computed by the high-level 
			/// device as "pFileDesc->uSector * Block_Size + Stream_Position", where Block_Size is obtained 
			/// via AK::StreamMgr::IAkLowLevelIOHook::GetBlockSize(). 
			virtual void BatchRead(
				AkUInt32						in_uNumTransfers,		///< Number of transfers to process
				BatchIoTransferItem*			in_pTransferItems 		///< List of transfer items to process
			) = 0;

			/// Write multiple data to multiple files (asynchronous).
			/// \remarks 
			/// - Queue up multiple write requests at once, using the provided array of in_pTransferItems. There will
			/// be in_uNumTransfers number of items in the array.
			/// - The pCallback within each BatchIoTransferItem::pTransferInfo must be called when completed.
			/// - The pointer to each BatchIoTransferItem::pTransferInfo will be valid until the high-level
			/// device is notified through the callback. However, the array of in_pTransferItems will not be valid.
			/// - File position passed in each BatchIoTransferItem::pTransferInfo takes the offset of this file relative 
			/// to AkFileDesc::hFile (described with AkFileDesc::uSector). It is computed by the high-level 
			/// device as "pFileDesc->uSector * Block_Size + Stream_Position", where Block_Size is obtained 
			/// via AK::StreamMgr::IAkLowLevelIOHook::GetBlockSize().
			virtual void BatchWrite(
				AkUInt32						in_uNumTransfers,		///< Number of transfers to process
				BatchIoTransferItem*			in_pTransferItems 		///< List of transfer items to process
			) = 0;

			/// Notifies that a transfer request is cancelled. It will be flushed by the streaming device when completed.
			/// Cancellation is normal and happens regularly; for example, whenever a sound stops before the end
			/// or stops looping. It happens even more frequently when buffering (AkDeviceSettings::fTargetAutoStmBufferLength 
			/// and AkDeviceSettings::uGranularity) is large and when you low-level IO hook accepts many concurrent requests
			/// at the same time.
			/// \remarks
			/// - BatchCancel() is an optional functionality that can be implemented as a no-op.
			/// - BatchCancel() simply informs the Low-Level I/O that a specific transfer will be flushed upon reception. 
			///	The Low-Level I/O may use this information to stop this transfer right away, or not (it is internally tagged
			///	by the high-level device as cancelled). Nevertheless, the callback function MUST be called for cancelled 
			///	transfers to be resolved.
			/// - When calling the callback function of a cancelled transfer, pass it *AK_Success*. Passing AK_Fail 
			/// to AkAsyncIOTransfer::pCallback has the effect of killing the stream once and for all. This is not
			/// what you want.
			/// - If io_bCancelAllTransfersForThisFile is set, you may cancel all transfers for this file at once.
			///	Leave io_bCancelAllTransfersForThisFile to true if you don't want to be called again. For example, if
			/// you don't do anything special in BatchCancel(), leave it to true. This will reduce the amount of useless calls.
			/// If you set it to false, BatchCancel() will be called again for each remaining pending transfer that need to be cancelled. 
			/// - If io_bCancelAllTransfersForThisFile is not set, BatchCancel() is only called for a subset of pending 
			///	transfers for this file. You must not set it to true, as BatchCancel() needs to be called explicitly for each transfer that 
			/// should be cancelled.
			/// \warning
			/// - The calling thread holds the stream's lock. You may call the callback function directly from here
			/// (if you can guarantee that the I/O buffer will not be accessed in the meantime), but you must not wait here 
			/// for another thread to call the callback function.
			/// - Likewise, if you resolve transfers with your own thread and use a lock to protect your transfers queue, 
			/// be careful not to run into a deadlock. BatchCancel() can be executed by any thread. Thus, if you need to lock your queue 
			/// in BatchCancel(), you must never hold this lock when calling back transfers, either from within BatchCancel() or from your 
			/// worker thread's routine. Lock your list, dequeue the transfer if you can, unlock, and call pCallback if and only if 
			/// the transfer was found and dequeued. On the other hand, if you choose not to do anything in BatchCancel(), the lock only protects 
			/// your list between Read()/Write() and your worker thread's routine, and since the device I/O thread does not hold the 
			/// stream's lock while calling Read()/Write(), your worker thread may therefore hold it while calling back transfers.
			/// - A race condition exists when cancelling all transfers (io_bCancelAllTransfersForThisFile is true) directly from within this hook. 
			/// If you handle the io_bCancelAllTransfersForThisFile == true case, you need to defer calling the completion callback to later 
			/// (from your usual I/O completion thread, for example). This will be fixed in a future version of Wwise.
			virtual void BatchCancel(
				AkUInt32						in_uNumTransfers,						///< Number of transfers to process
				BatchIoTransferItem*			in_pTransferItems,						///< List of transfer items to process
				bool**							io_ppbCancelAllTransfersForThisFile		///< Flag for each transfer indicating whether all transfers should be cancelled for this file (see notes in function description).
			) = 0;

			/// This function is called to provide information when file related errors occur. The base paths known by this IO hook should be returned in out_searchedPath.
			virtual AKRESULT OutputSearchedPaths(
				AKRESULT in_result,						///< Result of the open call
				const AkFileOpenData& in_FileOpen,		///< File name and flags passed to the Open call.
				AkOSChar* out_searchedPath,				///< Pre-allocated string buffer to be filled with all searched paths searched for the file.
				AkInt32 in_pathSize						///< The maximum size of the string
			) {	return AK_NotImplemented; };
		};

		/// File location resolver interface. There is one and only one File Location Resolver that is
		/// registered to the Stream Manager (using AK::StreamMgr::SetFileLocationResolver()). Its purpose
		/// is to resolve a file name or ID to a streaming device (I/O hook) that can handle the file.
		/// When your Low-Level I/O submodule uses a single device, you should create a standalone I/O
		/// hook which implements one of the I/O hooks defined above, as well 
		/// as the File Location Resolver. You then register this object to the Stream Manager as the 
		/// File Location Resolver.
		/// If you wish to create multiple devices, then you should have a separate object that implements
		/// AK::StreamMgr::IAkFileLocationResolver and registers to the Stream Manager as such. This object
		/// will be used to dispatch the file open request to the appropriate device. The strategy you will 
		/// use to select the correct device is up to you to implement.
		/// There is a built-in mechanism of chaining devices through GetNextPreferredDevice(). 
		/// If a device can't open a file GetNextPreferredDevice will be called again to get the next 
		/// device to check.
		class IAkFileLocationResolver
		{
		protected:
			/// Virtual destructor on interface to avoid warnings.
			virtual ~IAkFileLocationResolver(){}

		public:

			/// Determines which device to use to open a file. 
			/// If your File Resolver only handles one device, return AK_NotImplemented and the StreamMgr will use the only device configured.
			/// If it handles multiple devices, you can base the decision on where to get the file on any kind of heuristic: 
			/// file extension, file name, access rights, CodecID, etc.
			/// The order in which devices are searched is left to the implementer.
			/// This function will always be called first with io_idDevice = AK_INVALID_DEVICE_ID. 
			/// \return
			///		- AK_Success if there is a device to delegate the Open() call to. io_idDevice should be set to the proper AkDeviceID (as returned by AK::StreamMgr::CreateDevice).
			///		- AK_FileNotFound if all devices have been exhausted. 
			///		- AK_NotImplemented if there is only one device in the system and file resolution is trivial.
			/// \remark
			/// This can be called from multiple threads.
			/// Note that there is a 
			virtual AKRESULT GetNextPreferredDevice(
				AkAsyncFileOpenData& in_FileOpen,	///< File name and flags passed to the Open call.
				AkDeviceID& io_idDevice				///< In: last device used. Out: next device to use to open the file
				) 
			{ return AK_NotImplemented;	};
		};

		/// \name Audiokinetic implementation-specific Stream Manager factory.
		//@{
		/// Stream Manager factory.
		/// \remarks 
		/// - In order for the Stream Manager to work properly, you also need to create 
		/// at least one streaming device (and implement its I/O hook), and register the 
		/// File Location Resolver with AK::StreamMgr::SetFileLocationResolver().
		/// - Use AK::StreamMgr::GetDefaultSettings(), then modify the settings you want,
		/// then feed this function with them.
		/// \sa 
		/// - AK::IAkStreamMgr
		/// - AK::StreamMgr::SetFileLocationResolver()
		/// - AK::StreamMgr::GetDefaultSettings()
		AK_EXTERNAPIFUNC( IAkStreamMgr *, Create )( 
			const AkStreamMgrSettings &	in_settings		///< Stream manager initialization settings.
			);

		/// Get the default values for the Stream Manager's settings.
		/// \sa 
		/// - AK::StreamMgr::Create()
		/// - AkStreamMgrSettings
		/// - \ref streamingmanager_settings
		AK_EXTERNAPIFUNC( void, GetDefaultSettings )(
			AkStreamMgrSettings &		out_settings	///< Returned AkStreamMgrSettings structure with default values.
			);

		/// Get the one and only File Location Resolver registered to the Stream Manager.
		/// \sa
		/// - AK::StreamMgr::IAkFileLocationResolver
		/// - AK::StreamMgr::SetFileLocationResolver()
		AK_EXTERNAPIFUNC( IAkFileLocationResolver *, GetFileLocationResolver )();

		/// Register the one and only File Location Resolver to the Stream Manager.
		/// \sa 
		/// - AK::StreamMgr::IAkFileLocationResolver
		AK_EXTERNAPIFUNC( void, SetFileLocationResolver )(
			IAkFileLocationResolver *	in_pFileLocationResolver ///< Interface to your File Location Resolver
			);

		//@}

		/// \name Stream Manager: High-level I/O devices management.
		//@{
		/// Streaming device creation.
		/// Creates a high-level device, with specific settings. 
		/// You need to provide the associated low-level I/O hook, implemented on your side.
		/// \return The device ID. AK_INVALID_DEVICE_ID if there was an error and it could not be created.
		/// \warning 
		/// - This function is not thread-safe.
		/// \remarks 
		/// - You may use AK::StreamMgr::GetDefaultDeviceSettings() first to get default values for the 
		/// settings, change those you want, then feed the structure to this function.
		/// - The returned device ID should be kept by the Low-Level IO, to assign it to file descriptors
		/// in AK::StreamMgr::IAkLowLevelIOHook::BatchOpen().
		/// \return
		/// - AK_Success: Device was added to the system properly
		/// - AK_InsufficientMemory: Not enough memory to complete the operation
		/// - AK_InvalidParameter: One of the settings in AkDeviceSettings is out of range. Check asserts or debug console.
		/// \sa
		/// - AK::StreamMgr::IAkLowLevelIOHook
		/// - AK::StreamMgr::GetDefaultDeviceSettings()
		/// - \ref streamingmanager_settings
		AK_EXTERNAPIFUNC( AKRESULT, CreateDevice )(
			const AkDeviceSettings &	in_settings,		///< Device settings.
			IAkLowLevelIOHook *			in_pLowLevelHook,	///< Associated low-level I/O hook. Pass either a IAkLowLevelIOHook interface, consistent with the type of the scheduler.
			AkDeviceID&					out_idDevice		///< Assigned unique device id to use in all other functions of this interface.
			);
		/// Streaming device destruction.
		/// \return AK_Success if the device was successfully destroyed.
		/// \warning This function is not thread-safe. No stream should exist for that device when it is destroyed.
		AK_EXTERNAPIFUNC( AKRESULT, DestroyDevice )(
			AkDeviceID					in_deviceID         ///< Device ID of the device to destroy.
			);
		
		/// Execute pending I/O operations on all created I/O devices.
		/// This should only be called in single-threaded environments where an I/O device cannot spawn a thread.
		/// \return AK_Success when called from an appropriate environment, AK_NotCompatible otherwise.
		/// \sa 
		/// - AK::StreamMgr::CreateDevice()
		AK_EXTERNAPIFUNC( AKRESULT, PerformIO )();

		/// Get the default values for the streaming device's settings. Recommended usage
		/// is to call this function first, then pass the settings to AK::StreamMgr::CreateDevice().
		/// \sa 
		/// - AK::StreamMgr::CreateDevice()
		/// - AkDeviceSettings
		/// - \ref streamingmanager_settings
		AK_EXTERNAPIFUNC( void, GetDefaultDeviceSettings )(
			AkDeviceSettings &			out_settings		///< Returned AkDeviceSettings structure with default values.
			);
		//@}

		/// \name Language management.
		//@{
		/// Set the current language once and only once, here. The language name is stored in a static buffer 
		/// inside the Stream Manager. In order to resolve localized (language-specific) file location,
		/// AK::StreamMgr::IAkFileLocationResolver implementations query this string. They may use it to 
		/// construct a file path (for e.g. SDK/samples/SoundEngine/Common/AkFileLocationBase.cpp), or to
		/// find a language-specific file within a look-up table (for e.g. SDK/samples/SoundEngine/Common/AkFilePackageLUT.cpp).
		/// Pass a valid null-terminated string, without a trailing slash or backslash. Empty strings are accepted.
		/// You may register for language changes (see RegisterToLanguageChangeNotification()). 
		/// After changing the current language, all observers are notified.
		/// \return AK_Success if successful (if language string has less than AK_MAX_LANGUAGE_NAME_SIZE characters). AK_Fail otherwise.
		/// \warning Not multithread safe.
		/// \sa 
		/// - AK::StreamMgr::GetCurrentLanguage()
		/// - AK::StreamMgr::AddLanguageChangeObserver()
		AK_EXTERNAPIFUNC( AKRESULT, SetCurrentLanguage )(
			const AkOSChar *	in_pszLanguageName			///< Language name.
			);

		/// Get the current language. The language name is stored in a static buffer inside the Stream Manager, 
		/// with AK::StreamMgr::SetCurrentLanguage(). In order to resolve localized (language-specific) file location,
		/// AK::StreamMgr::IAkFileLocationResolver implementations query this string. They may use it to 
		/// construct a file path (for e.g. SDK/samples/SoundEngine/Common/AkFileLocationBase.cpp), or to
		/// find a language-specific file within a look-up table (for e.g. SDK/samples/SoundEngine/Common/AkFilePackageLUT.cpp).
		/// \return Current language.
		/// \sa AK::StreamMgr::SetCurrentLanguage()
		AK_EXTERNAPIFUNC( const AkOSChar *, GetCurrentLanguage )();

		/// Definition of handlers for language change notifications.
		/// Called after SetCurrentLanguage() is called.
		/// \warning Do not call AddLanguageChangeObserver or SetCurrentLanguage from within your handler.
		/// \warning Not multithread safe.
		/// \sa 
		/// - AK::StreamMgr::SetCurrentLanguage()
		/// - AK::StreamMgr::AddLanguageChangeObserver()
		AK_CALLBACK( void, AkLanguageChangeHandler )( 
			const AkOSChar * const in_pLanguageName,///< New language name.
			void * in_pCookie						///< Cookie that was passed to AddLanguageChangeObserver().
			);

		/// Register to language change notifications.
		/// \return AK_Success if successful, AK_Fail otherwise (no memory or no cookie).
		/// \warning Not multithread safe.
		/// \sa 
		/// - AK::StreamMgr::SetCurrentLanguage()
		/// - AK::StreamMgr::RemoveLanguageChangeObserver()
		AK_EXTERNAPIFUNC( AKRESULT, AddLanguageChangeObserver )(
			AkLanguageChangeHandler in_handler,	///< Callback function.
			void * in_pCookie					///< Cookie, passed back to AkLanguageChangeHandler. Must set.
			);

		/// Unregister to language change notifications. Use the cookie you have passed to 
		/// AddLanguageChangeObserver() to identify the observer.
		/// \warning Not multithread safe.
		/// \sa 
		/// - AK::StreamMgr::SetCurrentLanguage()
		/// - AK::StreamMgr::AddLanguageChangeObserver()
		AK_EXTERNAPIFUNC( void, RemoveLanguageChangeObserver )(
			void * in_pCookie					///< Cookie that was passed to AddLanguageChangeObserver().
			);

		/// \name Stream Manager: Cache management.
		//@{
		/// Flush cache of all devices. This function has no effect for devices where
		/// AkDeviceSettings::bUseStreamCache was set to false (no caching).
		/// \sa
		/// - \ref streamingmanager_settings
		AK_EXTERNAPIFUNC( void, FlushAllCaches )();
		
		//@}
	}
}

#endif //_AK_STREAM_MGR_MODULE_H_