Class CMMFDescriptor

class CMMFDescriptor : public CMMFClip;

Description

MultiMedia framework class. Represents a client side descriptor. May be source descriptor from which data is read or destination to which data is written

Derivation

• MDataSink - Abstract class representing a data sink
• MDataSource - Abstract class representing a data source
• CBase - Base class for all classes to be instantiated on the heap

• CMMFClip - Abstract class to represent a source or sink that contains a multimedia clip (i.e

• CMMFDescriptor - MultiMedia framework class

Members

Defined in CMMFDescriptor:
BufferEmptiedL(), BufferFilledL(), BytesFree(), CanCreateSinkBuffer(), CanCreateSourceBuffer(), ConstructSinkL(), ConstructSourceL(), CreateSinkBufferL(), CreateSourceBufferL(), EmptyBufferL(), FillBufferL(), ReadBufferL(), ReadBufferL(), ReadBufferL(), SetSize(), SinkDataTypeCode(), Size(), SourceDataTypeCode(), WriteBufferL(), WriteBufferL(), WriteBufferL(), ~CMMFDescriptor()

Inherited from CBase:
Extension_(), operator new()

Inherited from CMMFClip:
Delete()

Inherited from MDataSink:
DataSinkType(), NegotiateL(), NewSinkL(), SetSinkDataTypeCode(), SetSinkPrioritySettings(), SinkCustomCommand(), SinkPauseL(), SinkPlayL(), SinkPrimeL(), SinkStopL(), SinkThreadLogoff(), SinkThreadLogon()

Inherited from MDataSource:
DataSourceType(), NegotiateSourceL(), NewSourceL(), SetSourceDataTypeCode(), SetSourcePrioritySettings(), SourceCustomCommand(), SourcePauseL(), SourcePlayL(), SourcePrimeL(), SourceSampleConvert(), SourceStopL(), SourceThreadLogoff(), SourceThreadLogon()

virtual ~CMMFDescriptor();

Description

Destructor.

The default implementation closes the descriptor thread.

virtual TFourCC SourceDataTypeCode(TMediaId aMediaId);

Description

Returns the data type as a fourCC code for the CMMFDescriptor data source.

Parameters

TMediaId aMediaId The ID of the media for which the codec is obtained.

Return value

TFourCC The data type fourCC code.

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

Description

Loads aBuffer from iDes.

File read is asynchronous. CReadRequest is created to respond to completion.

Parameters

CMMFBuffer *aBuffer The buffer to be filled from the descriptor. MDataSink *aConsumer The data sink consumer of the buffer. TMediaId aMediaId Not used.

virtual void BufferEmptiedL(CMMFBuffer *aBuffer);

Description

CMMFDescriptor as a source is always passive so this function is not supported.

Parameters

CMMFBuffer *aBuffer The emptied buffer.

virtual TBool CanCreateSourceBuffer();

Description

Tests whether a source buffer can be created.

Return value

TBool A boolean indicating if the buffer can be created. EFalse if a CMMFDescriptor cannot create it's own buffer

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

Description

Creates a source buffer.

Parameters

TMediaId aMediaId The Media ID. TBool &aReference A boolean indicating if MDataSource owns the buffer. ETrue if MDataSource owns the buffer, EFalse if the caller owns the buffer.

Return value

CMMFBuffer * NULL as a CMMFFile cannot create it's own buffer

virtual TFourCC SinkDataTypeCode(TMediaId aMediaId);

Description

Returns the data type as a fourCC code of the CMMFDescriptor data sink.

Used by MDataSource and MDataSink.

Parameters

TMediaId aMediaId

Return value

TFourCC The data type fourCC code.

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

Description

Empties aBuffer into iDes.

Parameters

CMMFBuffer *aBuffer The buffer to be written to the descriptor. MDataSource *aSupplier The data source supplier of the buffer. TMediaId aMediaId The Media ID.

virtual void BufferFilledL(CMMFBuffer *aBuffer);

Description

CMMFDescriptor as a sink is always passive so this function is not supported.

Parameters

CMMFBuffer *aBuffer The filled buffer.

virtual TBool CanCreateSinkBuffer();

Description

Tests whether a sink buffer can be created.

Return value

TBool A boolean indicating if the sink buffer can be created. EFalse if a CMMFDescriptor cannot create it's own buffer.

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

Description

Creates a sink buffer.

Parameters

TMediaId aMediaId The Media ID. TBool &aReference A boolean indicating if MDataSource owns the buffer. ETrue if MDataSource owns the buffer, EFalse if the caller owns the buffer.

Return value

CMMFBuffer * NULL as a CMMFDescriptor cannot create it's own buffer

virtual void ReadBufferL(TInt aLength, CMMFBuffer *aBuffer, TInt aPosition, MDataSink *aConsumer);

Description

Loads aLength number of bytes into aBuffer from specified point in iDes.

Parameters

TInt aLength The number of bytes to be read into buffer. CMMFBuffer *aBuffer The buffer to be filled from the descriptor. TInt aPosition The offset into the descriptor at which to start reading. MDataSink *aConsumer The data sink consumer of the buffer

virtual void WriteBufferL(TInt aLength, CMMFBuffer *aBuffer, TInt aPosition, MDataSource *aSupplier);

Description

Empties aLength bytes from aBuffer into iDes at specified location.

Parameters

TInt aLength The number of bytes to be emptied from buffer. CMMFBuffer *aBuffer The data buffer containing bytes to be written. TInt aPosition The offset into the descriptor at which to start writing. MDataSource *aSupplier The data source to be notified when the write has been completed.

Leave codes

KErrNotReady If SinkPrimeL() and SinkThreadLogon() have not been called. KErrArgument If aLength<0 or aPosition<0 or aSupplier is NULL. KErrNotSupported If aBuffer is not of type KMMFDataBuffer.

virtual void ReadBufferL(CMMFBuffer *aBuffer, TInt aPosition, MDataSink *aConsumer);

Description

Loads aBuffer from specified point in iDes

Parameters

CMMFBuffer *aBuffer The buffer to be filled from the descriptor. TInt aPosition The offset into the descriptor at which to start reading. MDataSink *aConsumer The data sink consumer of the buffer.

virtual void WriteBufferL(CMMFBuffer *aBuffer, TInt aPosition, MDataSource *aSupplier);

Description

Empties aBuffer into iDes at specified location.

Parameters

CMMFBuffer *aBuffer The data buffer containing bytes to be written. TInt aPosition The offset into the descriptor at which to start writing. MDataSource *aSupplier The data source to be notified when the write has been completed.

virtual void ReadBufferL(CMMFBuffer *aBuffer, TInt aPosition);

Description

Loads aBuffer from specified point in iDes. Note that this is a synchronous read.

Parameters

CMMFBuffer *aBuffer The buffer to be filled from the descriptor. TInt aPosition The offset into the descriptor at which to start reading.

virtual void WriteBufferL(CMMFBuffer *aBuffer, TInt aPosition);

Description

Empties aBuffer into iFile at specified location. Note that this is a synchronous write

Parameters

CMMFBuffer *aBuffer The data buffer containing bytes to be written. TInt aPosition The offset into file at which to start writing.

virtual TInt64 BytesFree();

Description

Returns the amount of space available for the clip.

Return value

TInt64 The space available in descriptor (difference between length and maxlength).

virtual TInt Size();

Description

Returns the length of the clip.

Return value

TInt The length (not max length) of the descriptor.

virtual TInt SetSize(TInt aSize);

Description

Sets the size of the clip. This should be overriden in the derived classes, the default version returns KErrNotSupported.

Parameters

TInt aSize The size of the clip.

Return value

TInt An error code indicating if the function call was successful. KErrNone on success, otherwise another of the system-wide error codes.

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

Description

Performs sink construction dependant on the sink construction initialisation data aInitData.

Parameters

const TDesC8 &aInitData The TPckgC<TMMFDescriptorParams> descriptor package containing the descriptor and the thread ID for the descriptor.

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

Description

Performs source construction dependant on the source construction initialisation data aInitData.

Parameters

const TDesC8 &aInitData The TPckgC<TMMFDescriptorParams> descriptor package containing the descriptor and the thread ID for the descriptor.