Class CMMFDataPath

class CMMFDataPath : public CActive, public MDataSink, public MDataSource, public MAsyncEventHandler;

Description

Abstract utility class that moves data from a single data source to a single data sink, via a codec if required.

All functions are exported form the DLL and are virtual to allow plugins to define their own data paths.

Derivation

• MAsyncEventHandler - ...
• MDataSource - Abstract class representing a data source.
• MDataSink - Abstract class representing a data sink.

• CBase - Base class for all classes to be instantiated on the heap.

• CActive - The core class of the active object abstraction.

• CMMFDataPath - Abstract utility class that moves data from a single data source to a single dat...

Members

Defined in CMMFDataPath:

• AddDataSinkL(MDataSink *)Adds a data sink to the datapath and, if the source already exists, tries to est...
• AddDataSourceL(MDataSource *)Adds a data source to the datapath and, if the sink already exists, tries to est...
• BufferEmptiedL(CMMFBuffer *)Indicates the data sink has emptied the buffer.
• BufferFilledL(CMMFBuffer *)Indicates the data source has filled the specified buffer.
• CMMFDataPath(TMediaId,MAsyncEventHandler &)
• CanCreateSinkBuffer()Tests whether the data path can create a sink buffer.
• CanCreateSourceBuffer()Tests whether the data path can create a source buffer.
• ClearPlayWindowL()Sets the play window to the full length of clip.
• ConstructL(TUid)Takes UID of codec on construction, and if not an NULL codec sets the datapath u...
• ConstructSinkL(const TDesC8 &)Constructs a sink.
• ConstructSourceL(const TDesC8 &)Constructs a source.
• CreateSinkBufferL(TMediaId)Creates a sink buffer according to the specifed media ID.
• CreateSinkBufferL(TMediaId,TBool &)Creates a sink buffer according to the specifed media ID and reference.
• CreateSourceBufferL(TMediaId)Creates a source buffer.
• CreateSourceBufferL(TMediaId,TBool &)Creates a source buffer according to the specifed media ID and reference.
• DoCancel()Cancels the clip.
• DoSendEventToClient(TUid,TInt)Passes error handling and general messages up to clients.
• EConvertingConverting.
• EEndOfDataEnd of data.
• EInitializeSinkInitialize the sink.
• EInitializeSourceInitialize the source.
• ENeedSinkBufferSink buffer needed.
• ENeedSinkDataSink buffer does not contain data.
• ENeedSourceBufferSource buffer needed.
• ENeedSourceDataSource buffer does not contain data.
• ENeedToMatchSourceToSinkThere is more source data to send to the sink and need to match sink and source.
• ENoBuffersNo buffers needed.
• EPlayingPlaying.
• EPrimedPrimed.
• ERecordingRecording.
• ESendDataToSinkOutstanding data to send to sink.
• EStoppedStopped.
• EWaitSinkWaiting on a BufferEmptied callback from sink
• EWaitSourceWaiting on a BufferFilled callback from source
• EmptyBufferL(CMMFBuffer *,MDataSource *,TMediaId)Clears the specified buffer.
• EndOfData()Forces and end of data state on the datapath
• FillBufferL(CMMFBuffer *,MDataSink *,TMediaId)Fills the specified buffer.
• NewL(MAsyncEventHandler &)Allocates and constructs a data path.
• NewL(TMediaId,MAsyncEventHandler &)Allocates and constructs a data path according to the specified media ID.
• NewL(TUid,MAsyncEventHandler &)Allocates and constructs a data path according to the specified codec UID.
• NewL(TUid,TMediaId,MAsyncEventHandler &)Allocates and constructs a data path according to the specified codec UID.
• Pause()Pauses playing.
• PlayL()Starts an active scheduler 'play' loop.
• Position()constGets the data path position.
• PrimeL()Allocates buffers in preparation to play.
• ResetL()Deletes buffers if this datapath's sources and sinks own the buffers returned by...
• RunError(TInt)Handles errors coming from attached sources and passes them to the clients.
• RunL()Runs the clip depending on the current data path and transfer state.
• SendEventToClient(const TMMFEvent &)Passes error handling and general messages to clients.
• SetBlockLength(TUint)
• SetPlayWindowL(const TTimeIntervalMicroSeconds &,const TTimeIntervalMicroSeconds &)Sets the play window absolutely (i.e. the parameters are relative to the start o...
• SetPositionL(const TTimeIntervalMicroSeconds &)Sets the data path position.
• SinkDataTypeCode(TMediaId)Gets the sink's data type for the specified media ID.
• SourceDataTypeCode(TMediaId)Gets the source data type for the specified media ID.
• State()Returns the current data path state.
• Stop()Stops playing.
• TDataPathStateIndicates the state of the data path.
• TNeedBufferThis indicates what buffers are required in order to operate. If a real Codec is...
• TTransferStateIndicates the transfer state.
• iAllDataSentToSinkIndicates that all data has been sent to the sink.
• iBuffersToUseHolds the outcome of the call to DetermineBuffersToUseL
• iCachedSourceDurationThis value can be used to obtain the duration of the source when playing or conv...
• iCodecCodec in use. Null Codec is signified by == NULL
• iCodecProcessResultResult of processing the codec.
• iCompleteCallbackPointer to internal callback completion class
• iCurrentSinkFrameNumberThe sink's position in terms of frames or some other time fixed parameter.
• iCurrentSourceFrameNumberThe source's position in terms of frames or some other time fixed parameter.
• iDataPathCompletedErrorCodeDatapath completed because of an error; usually KErrNone.
• iDataPathCreatedSet to ETrue when the data path has a source and a sink and can send data from t...
• iDataSinkThe sink of data for which the CMMFDataPath is a MDataSource for
• iDataSourceThe source of data to which the CMMFDataPath is a MDataSink for.
• iEventHandlerEvent handler.
• iMediaIdIdentifies which media type and stream within MDataSource.
• iNoMoreSourceDataIndicates that all data has been obtained from the source (ETrue if there is no ...
• iObtainingAsyncSinkBufferIndicates asynchrous buffers from AudioOutput.
• iObtainingAsyncSourceBufferIndicates asynchrous buffers from AudioInput.
• iPauseCalledIndicates CMMFDataPath::DoPauseL() has been called.
• iPlayWindowEndPositionEnd position of the play window.
• iPlayWindowStartPositionStart position of the play window.
• iReferenceAudioSamplesPlayedHolds the number of samples played on audio output at a point where we want to r...
• iReferenceAudioSamplesRecordedHolds the number of samples recorded from audio input at a point where we want t...
• iSinkBufferThis is set to point to whichever sink buffer is in use.
• iSinkBufferWithSinkFlag to indicate that a buffer is with the sink.
• iSinkCanReceiveSet to true when the sink is able to accept data. EFalse otherwise.
• iSinkFourCCThe sink's data type. Same as the codec input data type.
• iSnkBufRefETrue if sink buffer is reference to object owned by someone else
• iSourceBufferThis is the pointer to whichever source buffer is in use
• iSourceBufferWithSourceFlag to indicate that a buffer is with the source.
• iSourceFourCCThe source's data type. Same as the codec output data type.
• iSrcBufRefETrue if the source buffer is reference to object owned by someone else.
• iStartPositionThe position audio will start playing from. When stopping, this is set to iPlayW...
• iStateCurrent data path state.
• iTransferStateCurrent transfer state.
• iUseSuppliedCodecUidSet to true if data path has to use a supplied codec in its construction.
• ~CMMFDataPath()Standard destructor.

Inherited from CActive:

• CActive(TInt)Constructs the active object with the specified priority.
• Cancel()Cancels the wait for completion of an outstanding request.
• Deque()Removes the active object from the active scheduler's list of active objects.
• EPriorityHighA priority higher than EPriorityUserInput.
• EPriorityIdleA low priority, useful for active objects representing background processing.
• EPriorityLowA priority higher than EPriorityIdle but lower than EPriorityStandard.
• EPriorityStandardMost active objects will have this priority.
• EPriorityUserInputA priority higher than EPriorityStandard; useful for active objects handling use...
• Extension_(TUint,TAny *&,TAny *)Extension function
• IsActive()constDetermines whether the active object has a request outstanding.
• IsAdded()constDetermines whether the active object has been added to the active scheduler's li...
• Priority()constGets the priority of the active object.
• SetActive()Indicates that the active object has issued a request and that it is now outstan...
• SetPriority(TInt)Sets the priority of the active object.
• TPriorityDefines standard priorities for active objects.
• iStatusThe request status associated with an asynchronous request.

Inherited from CBase:

• Delete(CBase *)Deletes the specified object.
• operator new(TUint)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TAny *)Initialises the object to binary zeroes.
• operator new(TUint,TLeave)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TLeave,TUint)Allocates the object from the heap and then initialises its contents to binary z...
• operator new(TUint,TUint)Allocates the object from the heap and then initialises its contents to binary z...

Inherited from MDataSink:

• DataSinkType()constReturns the UID identifying the type of data sink.
• MDataSink(TUid)Protected constructor.
• NegotiateL(MDataSource &)Allows the data sink to negotiate with a data source.
• NewSinkL(TUid,const TDesC8 &)Instantiates a new data sink.
• SetSinkDataTypeCode(TFourCC,TMediaId)Sets the data type as a fourCC code for the data sink.
• SetSinkPrioritySettings(const TMMFPrioritySettings &)Sets the sink priority settings.
• SinkCustomCommand(TMMFMessage &)Calls a sink specific custom command.
• SinkPauseL()Function to 'pause' the data sink.
• SinkPlayL()Function 'play' the data sink.
• SinkPrimeL()Function to 'prime' the data sink.
• SinkStopL()Function to 'stop' the data sink.
• SinkThreadLogoff()Function to 'logoff' the data sink from the same thread that sink consumes data ...
• SinkThreadLogon(MAsyncEventHandler &)Function to 'logon' the data sink to the same thread that sink will be consuming...

Inherited from MDataSource:

• CreateSourceBufferL(TMediaId,CMMFBuffer &,TBool &)Returns a buffer created by the data source.
• DataSourceType()constReturns the UID identifying the type of data source.
• MDataSource(TUid)Protected constructor.
• NegotiateSourceL(MDataSink &)Function to allow the data source to negotiate with a data sink
• NewSourceL(TUid,const TDesC8 &)Instantiates a data source.
• SetSourceDataTypeCode(TFourCC,TMediaId)Sets the data type as a fourCC code for the data source.
• SetSourcePrioritySettings(const TMMFPrioritySettings &)Function to set the source priority settings.
• SourceCustomCommand(TMMFMessage &)Function to call a source specific custom command.
• SourcePauseL()Function to 'pause' the data source.
• SourcePlayL()Function to 'play' the data source.
• SourcePrimeL()Function to 'prime' the data source.
• SourceSampleConvert()Indicates whether the data source supports sample rate conversion.
• SourceStopL()Function to 'stop' the data source.
• SourceThreadLogoff()Function to 'logoff' the data source from the same thread that source supplies d...
• SourceThreadLogon(MAsyncEventHandler &)Function to 'logon' the data source to the same thread that source will be suppl...

IMPORT_C static CMMFDataPath* NewL(MAsyncEventHandler &aEventHandler);

Description

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

Return value

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

Description

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

Return value

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

Description

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

Return value

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

Description

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

Return value

IMPORT_C virtual ~CMMFDataPath();

Description

Standard destructor.

protected: inline CMMFDataPath(TMediaId aMediaId, MAsyncEventHandler &aEventHandler);

Description

Parameters

protected: IMPORT_C void ConstructL(TUid aCodecUid=TUid::Null());

Description

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

Parameters

IMPORT_C virtual void ResetL();

Description

Deletes buffers if this datapath's sources and sinks own the buffers returned by CMMFDataPath::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.

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

Description

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

IMPORT_C virtual void BufferFilledL(CMMFBuffer *aBuffer);

Description

Indicates the data source has filled the specified buffer.

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

Parameters

IMPORT_C virtual TBool CanCreateSinkBuffer();

Description

Tests whether the data path can create a sink buffer.

The default implementation returns false.

Return value

IMPORT_C virtual CMMFBuffer* CreateSinkBufferL(TMediaId aMediaId);

Description

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

Return value

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

Description

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

Return value

IMPORT_C virtual TFourCC SinkDataTypeCode(TMediaId aMediaId);

Description

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

Parameters

Return value

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

Description

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

IMPORT_C virtual void BufferEmptiedL(CMMFBuffer *aBuffer);

Description

Indicates the data sink has emptied the buffer.

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

Parameters

IMPORT_C virtual TBool CanCreateSourceBuffer();

Description

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

IMPORT_C virtual CMMFBuffer* CreateSourceBufferL(TMediaId aMediaId);

Description

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

Return value

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

Description

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

Return value

IMPORT_C virtual TFourCC SourceDataTypeCode(TMediaId aMediaId);

Description

Gets the source data type for the specified media ID.

Parameters

Return value

IMPORT_C virtual void AddDataSourceL(MDataSource *aSource);

Description

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

Parameters

IMPORT_C virtual void AddDataSinkL(MDataSink *aSink);

Description

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

Parameters

IMPORT_C virtual void PrimeL();

Description

Allocates buffers in preparation to play.

Must be called before calling CMMFDataPath::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 CMMFDataPath::PrimeL().

IMPORT_C virtual void PlayL();

Description

Starts an active scheduler 'play' loop.

Can only play from the primed state.

IMPORT_C virtual void Pause();

Description

Pauses playing.

Sends KMMFErrorCategoryDataPathGeneralError to the client if an error occurs.

IMPORT_C virtual void Stop();

Description

Stops playing.

Resets datapath position - currently does not clean up buffers. Sends KMMFErrorCategoryDataPathGeneralError to the client if an error occurs.

IMPORT_C virtual TTimeIntervalMicroSeconds Position() const;

Description

Gets the data path position.

Return value

IMPORT_C virtual void SetPositionL(const TTimeIntervalMicroSeconds &aPosition);

Description

Sets the data path position.

Parameters

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

Description

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

Parameters

IMPORT_C virtual void ClearPlayWindowL();

Description

Sets the play window to the full length of clip.

IMPORT_C virtual TInt State();

Description

Returns the current data path state.

Return value

IMPORT_C virtual void RunL();

Description

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.

IMPORT_C virtual void DoCancel();

Description

Cancels the clip.

The default implementation is empty.

IMPORT_C virtual TInt RunError(TInt aError);

Description

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

Parameters

Return value

IMPORT_C TInt DoSendEventToClient(TUid aEventType, TInt aErrorCode);

Description

Passes error handling and general messages up to clients.

Parameters

Return value

IMPORT_C TInt SetBlockLength(TUint aBlockLength);

Description

Parameters

Return value

protected: IMPORT_C virtual void ConstructSourceL(const TDesC8 &aInitData);

Description

Constructs a source.

The default implementation leaves with KErrNotSupported.

Parameters

protected: IMPORT_C virtual void ConstructSinkL(const TDesC8 &aInitData);

Description

Constructs a sink.

Overridable constuction specific to this datasource.

The default implementation leaves with KErrNotSupported.

Parameters

protected: IMPORT_C virtual void EndOfData();

Description

Forces and end of data state on the datapath

private: IMPORT_C virtual TInt SendEventToClient(const TMMFEvent &aEvent);

Description

Passes error handling and general messages to clients.

Parameters

Return value

TDataPathState

Description

Indicates the state of the data path.

Mimics typical MultiMedia behaviour of stopped, primed and playing

protected: TTransferState

Description

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.

protected: TNeedBuffer

Description

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.

protected: MAsyncEventHandler & iEventHandler;

Description

Event handler.

protected: MDataSource * iDataSource;

Description

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

protected: MDataSink * iDataSink;

Description

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

protected: TBool iSinkCanReceive;

Description

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

protected: TFourCC iSinkFourCC;

Description

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

protected: TFourCC iSourceFourCC;

Description

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

protected: TMediaId iMediaId;

Description

Identifies which media type and stream within MDataSource.

protected: CMMFCodec * iCodec;

Description

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

protected: TCodecProcessResult iCodecProcessResult;

Description

Result of processing the codec.

protected: TBool iDataPathCreated;

Description

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

protected: TDataPathState iState;

Description

Current data path state.

See also:

• CMMFDataPath::TDataPathStateIndicates the state of the data path.

protected: TTransferState iTransferState;

Description

Current transfer state.

See also:

• CMMFDataPath::TTransferStateIndicates the transfer state.

protected: TBool iUseSuppliedCodecUid;

Description

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

protected: CMMFBuffer * iSinkBuffer;

Description

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

protected: CMMFBuffer * iSourceBuffer;

Description

This is the pointer to whichever source buffer is in use

protected: TUint iCurrentSourceFrameNumber;

Description

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

protected: TUint iCurrentSinkFrameNumber;

Description

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

protected: TBool iNoMoreSourceData;

Description

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

protected: TBool iAllDataSentToSink;

Description

Indicates that all data has been sent to the sink.

protected: TUint iDataPathCompletedErrorCode;

Description

Datapath completed because of an error; usually KErrNone.

protected: TTimeIntervalMicroSeconds iPlayWindowStartPosition;

Description

Start position of the play window.

protected: TTimeIntervalMicroSeconds iPlayWindowEndPosition;

Description

End position of the play window.

protected: TTimeIntervalMicroSeconds iStartPosition;

Description

The position audio will start playing from. When stopping, this is set to iPlayWindowStartPosition. When pausing, this is set to the current position.

protected: TTimeIntervalMicroSeconds iCachedSourceDuration;

Description

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.

protected: TBool iSrcBufRef;

Description

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

protected: TBool iSnkBufRef;

Description

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

protected: TBool iObtainingAsyncSourceBuffer;

Description

Indicates asynchrous buffers from AudioInput.

protected: TBool iObtainingAsyncSinkBuffer;

Description

Indicates asynchrous buffers from AudioOutput.

protected: TBool iPauseCalled;

Description

Indicates CMMFDataPath::DoPauseL() has been called.

protected: TBool iSourceBufferWithSource;

Description

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.

protected: TBool iSinkBufferWithSink;

Description

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.

protected: TInt iReferenceAudioSamplesPlayed;

Description

Holds the number of samples played on audio output at a point where we want to reference play duration from.

protected: TInt iReferenceAudioSamplesRecorded;

Description

Holds the number of samples recorded from audio input at a point where we want to reference record duration from.

protected: CCompleteCallback * iCompleteCallback;

Description

Pointer to internal callback completion class

protected: TInt iBuffersToUse;

Description

Holds the outcome of the call to DetermineBuffersToUseL