CMMFDataPath Class Reference

iAllDataSentToSink

[protected]

Indicates that all data has been sent to the sink.

iBuffersToUse

TInt

iBuffersToUse

[protected]

Holds the outcome of the call to DetermineBuffersToUseL

iCachedSourceDuration

iCachedSourceDuration

[protected]

This value can be used to obtain the duration of the source when playing or converting.

This is an optimisation as this value will not change if we are playing or converting.

iCodec

CMMFCodec *

iCodec

[protected]

Codec in use. Null Codec is signified by == NULL

iCodecProcessResult

TCodecProcessResult

iCodecProcessResult

[protected]

Result of processing the codec.

iCompleteCallback

CCompleteCallback *

iCompleteCallback

[protected]

Pointer to internal callback completion class

iCurrentSinkFrameNumber

iCurrentSinkFrameNumber

[protected]

The sink's position in terms of frames or some other time fixed parameter.

iCurrentSourceFrameNumber

iCurrentSourceFrameNumber

[protected]

The source's position in terms of frames or some other time fixed parameter.

iDataPathCompletedErrorCode

iDataPathCompletedErrorCode

[protected]

Datapath completed because of an error; usually KErrNone.

iDataPathCreated

iDataPathCreated

[protected]

Set to ETrue when the data path has a source and a sink and can send data from the source to the sink.

iDataSink

MDataSink *

iDataSink

[protected]

The sink of data for which the CMMFDataPath is a MDataSource for

iDataSource

MDataSource *

iDataSource

[protected]

The source of data to which the CMMFDataPath is a MDataSink for.

iEventHandler

MAsyncEventHandler &

iEventHandler

[protected]

Event handler.

iMediaId

iMediaId

[protected]

Identifies which media type and stream within MDataSource.

iNoMoreSourceData

iNoMoreSourceData

[protected]

Indicates that all data has been obtained from the source (ETrue if there is no more source data).

iObtainingAsyncSinkBuffer

iObtainingAsyncSinkBuffer

[protected]

Indicates asynchrous buffers from AudioOutput.

iObtainingAsyncSourceBuffer

iObtainingAsyncSourceBuffer

[protected]

Indicates asynchrous buffers from AudioInput.

iPauseCalled

iPauseCalled

[protected]

Indicates DoPauseL() has been called.

iPlayWindowEndPosition

iPlayWindowEndPosition

[protected]

End position of the play window.

iPlayWindowStartPosition

iPlayWindowStartPosition

[protected]

Start position of the play window.

iReferenceAudioSamplesPlayed

TInt

iReferenceAudioSamplesPlayed

[protected]

Holds the number of samples played on audio output at a point where we

want to reference play duration from.

iReferenceAudioSamplesRecorded

TInt

iReferenceAudioSamplesRecorded

[protected]

Holds the number of samples recorded from audio input at a point where we

want to reference record duration from.

iSinkBuffer

iSinkBuffer

[protected]

This is set to point to whichever sink buffer is in use.

iSinkBufferWithSink

iSinkBufferWithSink

[protected]

Flag to indicate that a buffer is with the sink.

This are necessary as it is imperrative that when a buffer is with the sink, it must

not be referenced in any way. The reason for this is that it is not mandated that sinks

maintain buffer references. For example, it is valid for DevSound to request more audio data in a

different buffer to the one supplied to it.

iSinkCanReceive

iSinkCanReceive

[protected]

Set to true when the sink is able to accept data. EFalse otherwise.

iSinkFourCC

TFourCC

iSinkFourCC

[protected]

The sink's data type. Same as the codec input data type.

iSnkBufRef

iSnkBufRef

[protected]

ETrue if sink buffer is reference to object owned by someone else

iSourceBuffer

iSourceBuffer

[protected]

This is the pointer to whichever source buffer is in use

iSourceBufferWithSource

iSourceBufferWithSource

[protected]

Flag to indicate that a buffer is with the source.

This is necessary as it is imperrative that when a buffer is with the source, it must

not be referenced in any way. The reason for this is that it is not mandated that sources

maintain buffer references. For example, it is valid for DevSound to return recorded data in a

different buffer to the one supplied to it.

iSourceFourCC

TFourCC

iSourceFourCC

[protected]

The source's data type. Same as the codec output data type.

iSrcBufRef

iSrcBufRef

[protected]

ETrue if the source buffer is reference to object owned by someone else.

iStartPosition

iStartPosition

[protected]

The position audio will start playing from.

When stopping, this is set to iPlayWindowStartPosition.

When pausing, this is set to the current position.

iState

TDataPathState

iState

[protected]

Current data path state.

iTransferState

TTransferState

iTransferState

[protected]

Current transfer state.

iUseSuppliedCodecUid

iUseSuppliedCodecUid

[protected]

Set to true if data path has to use a supplied codec in its construction.

Member Enumeration Documentation

Enum TDataPathState

Indicates the state of the data path.

Mimics typical MultiMedia behaviour of stopped, primed and playing

Enumerator	Value	Description
EStopped		Stopped.
EPrimed		Primed.
EPlaying		Playing.
ERecording		Recording.
EConverting		Converting.

Enum TNeedBuffer

This indicates what buffers are required in order to operate.

If a real Codec is in use, buffers are required from both source and sink,

else only one is required and source is preferred.

Enumerator	Value	Description
ENoBuffers	0x0	No buffers needed.
ENeedSinkBuffer	0x01	Sink buffer needed.
ENeedSourceBuffer	0x10	Source buffer needed.

Enum TTransferState

Indicates the transfer state.

Buffers maybe be filled, emptied, or have "one" shot initialisatings performed upon them.

TTransferState is used within the datapath RunL which drives databuffer exchange.

Enumerator	Value	Description
EWaitSink		Waiting on a BufferEmptied callback from sink
EWaitSource		Waiting on a BufferFilled callback from source
EInitializeSink		Initialize the sink.
EInitializeSource		Initialize the source.
ENeedSourceData		Source buffer does not contain data.
ENeedSinkData		Sink buffer does not contain data.
ENeedToMatchSourceToSink		There is more source data to send to the sink and need to match sink and source.
ESendDataToSink		Outstanding data to send to sink.
EEndOfData		End of data.

Constructor & Destructor Documentation

CMMFDataPath ( TMediaId, MAsyncEventHandler & )

CMMFDataPath	(	TMediaId	aMediaId,
		MAsyncEventHandler &	aEventHandler
	)	[protected, inline]

~CMMFDataPath ( )

IMPORT_C

~CMMFDataPath

(

)

[virtual]

Standard destructor.

Member Function Documentation

AddDataSinkL ( MDataSink * )

IMPORT_C void

AddDataSinkL

(

MDataSink *

aSink

)

[virtual]

Adds a data sink to the datapath and, if the source already exists, tries to establish a connection

between the source and sink.

Parameters
aSink	The data sink to add to the data path.

AddDataSourceL ( MDataSource * )

IMPORT_C void

AddDataSourceL

(

MDataSource *

aSource

)

[virtual]

Adds a data source to the datapath and, if the sink already exists, tries to establish a connection

between the source and sink.

Parameters
aSource	The data source to add to the data path.

AudioSamplesPlayed ( )

TInt

AudioSamplesPlayed

(

)

const [protected]

AudioSamplesRecorded ( )

TInt

AudioSamplesRecorded

(

)

const [protected]

BufferEmptiedL ( CMMFBuffer * )

IMPORT_C void

BufferEmptiedL

(

aBuffer

)

[virtual]

Reimplemented from MDataSource::BufferEmptiedL(CMMFBuffer *)

Indicates the data sink has emptied the buffer.

Called by the CMMFDataPath's MDataSink when it has emptied the buffer

Parameters
aBuffer	The emptied buffer.

BufferFilledL ( CMMFBuffer * )

IMPORT_C void

BufferFilledL

(

aBuffer

)

[virtual]

Reimplemented from MDataSink::BufferFilledL(CMMFBuffer *)

Indicates the data source has filled the specified buffer.

Called by the CMMFDataPath's MDataSource when it has filled the buffer.

Parameters
aBuffer	A pointer to the filled buffer.

CalculateAudioInputPosition ( )

CalculateAudioInputPosition

(

)

const [protected]

CalculateAudioOutputPosition ( )

CalculateAudioOutputPosition

(

)

const [protected]

CanCreateSinkBuffer ( )

IMPORT_C TBool

CanCreateSinkBuffer

(

)

[virtual]

Reimplemented from MDataSink::CanCreateSinkBuffer()

Tests whether the data path can create a sink buffer.

The default implementation returns false.

Return Value: ETrue if the data path can create a sink buffer. EFalse if the data path cannot create a sink buffer.

CanCreateSourceBuffer ( )

IMPORT_C TBool

CanCreateSourceBuffer

(

)

[virtual]

Reimplemented from MDataSource::CanCreateSourceBuffer()

Tests whether the data path can create a source buffer.

Would expect datapath to always return NULL, so this is a default implementation of a pure virtual from MDataSink.

The default implementation returns EFalse.

Return Value: ETrue if the data path can create a source buffer. EFalse if the data path cannot create a source buffer.

ClearPlayWindowL ( )

IMPORT_C void

ClearPlayWindowL

(

)

[virtual]

Sets the play window to the full length of clip.

ConstructL ( TUid )

IMPORT_C void

ConstructL

(

TUid

aCodecUid = KNullUid

)

[protected]

Takes UID of codec on construction, and if not an NULL codec sets the datapath up for codec instantiation.

Parameters
aCodecUid	The UID of the codec.

ConstructSinkL ( const TDesC8 & )

IMPORT_C void

ConstructSinkL

(

const TDesC8 &

aInitData

)

[protected, virtual]

Reimplemented from MDataSink::ConstructSinkL(const TDesC8 &)

Constructs a sink.

Overridable constuction specific to this datasource.

The default implementation leaves with KErrNotSupported.

Parameters
aInitData	The initialisation data.

ConstructSourceL ( const TDesC8 & )

IMPORT_C void

ConstructSourceL

(

const TDesC8 &

aInitData

)

[protected, virtual]

Reimplemented from MDataSource::ConstructSourceL(const TDesC8 &)

Constructs a source.

The default implementation leaves with KErrNotSupported.

Parameters
aInitData	The initialisation data.

CreateSinkBufferL ( TMediaId )

IMPORT_C CMMFBuffer *

CreateSinkBufferL

(

aMediaId

)

[virtual]

Creates a sink buffer according to the specifed media ID.

Intended for synchronous usage (buffers supplied by datapath for an MDataSink).

This method is essentially a dummy implementation of an MDataSink pure virtual.

The default implementation returns NULL.

Parameters
aMediaId	An optional mediaID parameter when there are multiple buffers arriving of different media types.

Return Value: Returns NULL in this instance as datapath can't create sink buffers

CreateSinkBufferL ( TMediaId, TBool & )

IMPORT_C CMMFBuffer *	CreateSinkBufferL	(	TMediaId	aMediaId,
			TBool &	aReference
		)	[virtual]

Reimplemented from MDataSink::CreateSinkBufferL(TMediaId,TBool &)

Creates a sink buffer according to the specifed media ID and reference.

Intended for asynchronous usage (buffers supplied by Devsound device).

This method is essentially a dummy implementation of an MDataSink pure virtual.

The default implementation returns NULL.

Parameters
aMediaId	An optional mediaID parameter when there are multiple buffers arriving for different media types.
aReference	A boolean indicating buffer ownership.

Return Value: Returns NULL in this instance as datapath can't create sink buffers.

CreateSourceBufferL ( TMediaId )

IMPORT_C CMMFBuffer *

CreateSourceBufferL

(

aMediaId

)

[virtual]

Creates a source buffer.

Intended for synchronous usage (buffers supplied by datapath for a MDataSource)

This method is essentially a dummy implementation of an MDataSource pure virtual.

The default implementation leaves with KErrNotSupported and returns NULL.

Parameters
aMediaId	An optional mediaID parameter when there are multiple buffers arriving of different media types.

Return Value: A pointer to a newly created buffer. Returns NULL in this instance as datapath can't create source buffers

CreateSourceBufferL ( TMediaId, TBool & )

IMPORT_C CMMFBuffer *	CreateSourceBufferL	(	TMediaId	aMediaId,
			TBool &	aReference
		)	[virtual]

Reimplemented from MDataSource::CreateSourceBufferL(TMediaId,TBool &)

Creates a source buffer according to the specifed media ID and reference.

Intended for asynchronous usage (buffers supplied by datapath for a MDataSource)

This method is essentially a dummy implementation of an MDataSource pure virtual.

The default implementation leaves with KErrNotSupported and returns NULL.

Parameters
aMediaId	An optional mediaID parameter when there are multiple buffers arriving of different media types.
aReference	A boolean indicating buffer ownership. ETrue if the MDataSource owns the buffer, EFalse if the caller owns the buffer.

Return Value: A pointer to a newly created buffer. Returns NULL in this instance as datapath can't create source buffers.

DetermineBuffersToUseL ( void )

TInt

DetermineBuffersToUseL

(

void

)

const [protected]

DoCancel ( )

IMPORT_C void

DoCancel

(

)

[virtual]

Reimplemented from CActive::DoCancel()

Cancels the clip.

The default implementation is empty.

DoSendEventToClient ( TUid, TInt )

IMPORT_C TInt	DoSendEventToClient	(	TUid	aEventType,
			TInt	aErrorCode
		)

Passes error handling and general messages up to clients.

Parameters
aEventType	Category code for the event. Category codes can be used as unique identifers.
aErrorCode	Standard error code.

Return Value: The event code sent to client.

EmptyBufferL ( CMMFBuffer , MDataSource , TMediaId )

IMPORT_C void	EmptyBufferL	(	CMMFBuffer *	aBuffer,
			MDataSource *	aSupplier,
			TMediaId	aMediaId
		)	[virtual]

Reimplemented from MDataSink::EmptyBufferL(CMMFBuffer *,MDataSource *,TMediaId)

Clears the specified buffer.

Pure virtual dummy implementation, not needed by datapath

comes from MDataSink - CMMFData path is a sink to its MDataSource.

This is only required for an active push MDataSource requesting a buffer empty.

Parameters
aBuffer	The buffer to empty.
aSupplier	The MDataSource supplying this buffer.
aMediaId	An optional mediaID parameter when there are multiple buffers arriving of different media types.

EndOfData ( )

IMPORT_C void

EndOfData

(

)

[protected, virtual]

Forces and end of data state on the datapath

FillBufferL ( CMMFBuffer , MDataSink , TMediaId )

IMPORT_C void	FillBufferL	(	CMMFBuffer *	aBuffer,
			MDataSink *	aConsumer,
			TMediaId	aMediaId
		)	[virtual]

Reimplemented from MDataSource::FillBufferL(CMMFBuffer *,MDataSink *,TMediaId)

Fills the specified buffer.

Pure virtual dummy implementation, not needed by datapath

comes from MDataSink - CMMFData path is a source to its MDataSink

Only required for an active pull MDataSink requesting a buffer fill. The default implementation is empty.

Parameters
aBuffer	The buffer to fill.
aConsumer	The MDataSink supplying this buffer.
aMediaId	An optional mediaID parameter when there are multiple buffers arriving of different media types

InputPosition ( )

InputPosition

(

)

const [protected]

NewL ( MAsyncEventHandler & )

IMPORT_C CMMFDataPath *

NewL

(

MAsyncEventHandler &

aEventHandler

)

[static]

Allocates and constructs a data path.

Use this function if the codec UID is not already known by CMMFController

and there is no data path ambiguity - ie only one data path is possible.

Will create codec via fourCC.

Parameters
aEventHandler	Installs an event handler to provide message passing between clients and sources/sinks.

Return Value: Newly constructed data path object.

NewL ( TMediaId, MAsyncEventHandler & )

IMPORT_C CMMFDataPath *	NewL	(	TMediaId	aMediaId,
			MAsyncEventHandler &	aEventHandler
		)	[static]

Allocates and constructs a data path according to the specified media ID.

Use this function if the codec UID is not already known by CMMFController

and there is ambiguity with the data path ie. there is more than one possible data path.

Parameters
aMediaId	Optional media ID parameter when there are multiple media types.
aEventHandler	Installs an event handler to provide message passing between clients and sources/sinks.

Return Value: A newly constructed data path object.

NewL ( TUid, MAsyncEventHandler & )

IMPORT_C CMMFDataPath *	NewL	(	TUid	aCodecUid,
			MAsyncEventHandler &	aEventHandler
		)	[static]

Allocates and constructs a data path according to the specified codec UID.

Use this function if the codec UID is already known by CMMFController

and there is no data path ambiguity ie. only one data path is possible

will create codec explicitly using the supplied codec Uid

Parameters
aCodecUid	Optional mediaID parameter when there are multiple media types
aEventHandler	Installs an event handler to provide message passing between clients and sources/sinks.

Return Value: A newly constructed data path object.

NewL ( TUid, TMediaId, MAsyncEventHandler & )

IMPORT_C CMMFDataPath *	NewL	(	TUid	aCodecUid,
			TMediaId	aMediaId,
			MAsyncEventHandler &	aEventHandler
		)	[static]

Allocates and constructs a data path according to the specified codec UID.

Use this function if the codec UID is already known by CMMFController

and there is ambiguity ie. more than one possible data path.

TMediaId used to select the path.

Parameters
aCodecUid	The codec UID.
aMediaId	Optional mediaID parameter when there are multiple media types.
aEventHandler	Installs an event handler to provide message passing between clients and sources/sinks.

Return Value: A newly constructed data path object.

OutputPosition ( )

OutputPosition

(

)

const [protected]

Pause ( )

IMPORT_C void

Pause

(

)

[virtual]

Pauses playing.

Sends KMMFErrorCategoryDataPathGeneralError to the client if an error occurs.

PlayL ( )

IMPORT_C void

PlayL

(

)

[virtual]

Starts an active scheduler 'play' loop.

Can only play from the primed state.

Position ( )

IMPORT_C TTimeIntervalMicroSeconds

Position

(

)

const [virtual]

Gets the data path position.

Return Value: The data path position.

PrimeL ( )

IMPORT_C void

PrimeL

(

)

[virtual]

Allocates buffers in preparation to play.

Must be called before calling PlayL().

iSnkBufRef and iSrcBufRef contain ETrue if these buffers are created and owned by a MDataSource or MDataSink

For clean-up purposes, datapath only cleans up buffers allocated directly by PrimeL().

ResetL ( )

IMPORT_C void

ResetL

(

)

[virtual]

Deletes buffers if this datapath's sources and sinks own the buffers returned by PrimeL().

Typically if buffers are created asychronously, the datapath doesn't own the buffer

so leaves cleanup handling to the owner sources/sinks.

Called when source and sink needs to be de-referenced. Sets iDataPathCreated, iSinkCanReceive,

iSnkBufRef and iSrcBufRef to EFalse; sets iState to EStopped.

RunError ( TInt )

IMPORT_C TInt

RunError

(

TInt

aError

)

[virtual]

Reimplemented from CActive::RunError(TInt)

Handles errors coming from attached sources and passes them to the clients.

Parameters
aError	Standard error code (KErrNone = No Error).

Return Value: The event code returned to the data path. KErrNone if end of file is encountered.

RunL ( )

IMPORT_C void

RunL

(

)

[virtual]

Reimplemented from CActive::RunL()

Runs the clip depending on the current data path and transfer state.

For example, fills the sink buffer if TDataPathState is EPlaying and TTransferState is ENeedSinkData.

SetBlockLength ( TUint )

IMPORT_C TInt

SetBlockLength

(

aBlockLength

)

SetPlayWindowL ( const TTimeIntervalMicroSeconds &, const TTimeIntervalMicroSeconds & )

IMPORT_C void	SetPlayWindowL	(	const TTimeIntervalMicroSeconds &	aStart,
			const TTimeIntervalMicroSeconds &	aEnd
		)	[virtual]

Sets the play window absolutely (i.e. the parameters are relative to the start of the entire clip).

Parameters
aStart	The offset from the start of the Clip
aEnd	The offset from the end of the clip (if this is less than aStart, then the two will be inverted).

SetPositionL ( const TTimeIntervalMicroSeconds & )

IMPORT_C void

SetPositionL

(

const TTimeIntervalMicroSeconds &

aPosition

)

[virtual]

Sets the data path position.

Parameters
aPosition	The data path position.

SinkDataTypeCode ( TMediaId )

IMPORT_C TFourCC

SinkDataTypeCode

(

aMediaId

)

[virtual]

Reimplemented from MDataSink::SinkDataTypeCode(TMediaId)

Gets the sink's data type for the specified media ID.

Parameters
aMediaId	An optional parameter to specifiy the specific stream when datasource contains more than one stream of data

Return Value: The sink's data type.

SourceDataTypeCode ( TMediaId )

IMPORT_C TFourCC

SourceDataTypeCode

(