CTransformInputPin Class

The CTransformInputPin class implements the input pin of a simple transform filter. It is the class assigned to the m_pInput data member of the CTransformFilter class. Typically, you can create objects derived from CTransformFilter without modifying the CTransformInputPin class. That is, you can usually override the member functions in CTransformFilter that are called by member functions of this class. This means that you need not derive your own classes for either of the pin classes.

However, if you want to override this class and have your filter class derived from CTransformFilter, you must override the CTransformFilter::GetPin member function to create pins of your derived class.

Protected Data Members

Name	Description
m_pTransformFilter	Pointer to the owning CTransformFilter object.

Member Functions

Name	Description
CTransformInputPin	Constructs a CTransformInputPin object.
CurrentMediaType	Retrieves the media type currently assigned to the filter.

Overridable Member Functions

Name	Description
BreakConnect	Informs the derived class when the connection is broken.
CheckConnect	Informs the derived class when the connection process is starting.
CheckMediaType	Determines if the pin can use a specified media type.
CheckStreaming	Verifies conditions for continuing with a streaming operation.
CompleteConnect	Informs the derived class when the connection process has completed.
SetMediaType	Informs the derived class when the media type is established for the connection.

Implemented IPin Methods

Name	Description
BeginFlush	Informs the pin to begin a flush operation.
EndFlush	Informs the pin to end a flush operation and notifies the pin that it can start accepting data again.
EndOfStream	Informs the input pin that no additional data is expected until a new run command is issued.
NewSegment	Specifies that samples following this call are grouped as a segment with a given start time, stop time, and rate.
QueryId	Retrieves an identifier for the pin.

Implemented IMemInputPin Methods

Name	Description
Receive	Receives the next block of data from the stream.

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CTransformInputPin::BeginFlush

CTransformInputPin Class

Informs the pin to begin a flush operation.

HRESULT BeginFlush(void);

Return Values

Returns an HRESULT value.

Remarks

This member function implements the IPin::BeginFlush method and overrides the CBaseInputPin::BeginFlush member function. It checks to see if the pin is connected, and then calls CBaseInputPin::BeginFlush, and finally calls the CTransformFilter::BeginFlush member function.

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CTransformInputPin::BreakConnect

CTransformInputPin Class

Informs the derived class when the connection is broken.

HRESULT BreakConnect( );

Return Values

Returns NOERROR in this implementation.

Remarks

This member function overrides the CBasePin::BreakConnect member function and calls the CTransformFilter::BreakConnect member function. Override CTransformFilter::BreakConnect to undo anything carried out in CTransformInputPin::CheckConnect (such as releasing extra interfaces).

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CTransformInputPin::CheckConnect

CTransformInputPin Class

Informs the derived class when the connection process is starting.

HRESULT CheckConnect(
  IPin *pPin
  );

Parameters

pPin

Pointer to the IPin interface of the connecting pin.

Return Values

Returns NOERROR by default.

Remarks

This member function overrides the CBasePin::CheckConnect member function and calls the CTransformFilter::CheckConnect member function. Override CTransformFilter::CheckConnect to add additional interfaces.

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CTransformInputPin::CheckMediaType

CTransformInputPin Class

Determines if the pin can use a specified media type.

HRESULT CheckMediaType(
  const CMediaType* mtIn
  );

Parameters

mtIn

Pointer to a media type object.

Return Values

No return value.

Remarks

This member function calls the pure-virtual CTransformFilter::CheckInputType member function, which must be overridden when deriving a class from the CTransformFilter class. The overridden CheckInputType member function is responsible for determining which media types the input pin supports.

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CTransformInputPin::CheckStreaming

CTransformInputPin Class

Verifies conditions for continuing with a streaming operation.

HRESULT CheckStreaming( );

Return Values

Returns one of the following HRESULT values, depending on the state.

Value	Meaning
S_FALSE	Currently in flushing state.
S_OK	Receive or EndOfStream operations can safely proceed.
VFW_E_NOT_CONNECTED	The output pin either does not exist or isn't connected.
VFW_E_RUNTIME_ERROR	A run-time error occurred when processing a previous sample.
VFW_E_WRONG_STATE	The filter is in the State_Stopped state.

Remarks

This member function overrides the CBaseInputPin::CheckStreaming member function and calls that base class implementation for most of the condition checks. It determines if the pin is connected, if it is in a paused or running state, and if it is not currently flushing data or processing a run-time error.

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CTransformInputPin::CompleteConnect

CTransformInputPin Class

Informs the derived class when the connection process has been completed.

HRESULT CompleteConnect(
  IPin *pReceivePin
  );

Parameters

pReceivePin

Pointer to the input pin being connected to.

Return Values

Returns an HRESULT value.

Remarks

This member function overrides the CBasePin::CompleteConnect member function. It calls the base class CBasePin::CompleteConnect member function and then calls CTransformFilter::CompleteConnect.

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CTransformInputPin::CTransformInputPin

CTransformInputPin Class

Constructs a CTransformInputPin object.

CTransformInputPin(
  TCHAR *pObjectName,
  CTransformFilter *pTransformFilter,
  HRESULT * phr,
  LPCWSTR pName
  );

Parameters

pObjectName

Name of the CTransformInputPin object.

pTransformFilter

Pointer to the CTransformFilter class.

phr

Pointer to an HRESULT value in which to return resulting information. This should be modified only if a failure occurs. If it is a failure code on input, construction can be terminated, but in any case the destructor will be called by the creator when the HRESULT error is detected.

pName

Name of the pin.

Return Values

No return value.

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CTransformInputPin::CurrentMediaType

CTransformInputPin Class

Retrieves the media type currently assigned to the filter.

CMediaType& CurrentMediaType( );

Return Values

Returns the value of CBasePin::m_mt.

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CTransformInputPin::EndFlush

CTransformInputPin Class

Informs the pin to end a flush operation and notifies the pin that it can start accepting data again.

HRESULT EndFlush(void);

Return Values

Returns an HRESULT value.

Remarks

This member function implements the IPin::EndFlush method and overrides the CBaseInputPin::EndFlush member function. It checks to see if the pin is connected, calls the CBaseInputPin::EndFlush member function, and finally calls the CTransformFilter::EndFlush member function.

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CTransformInputPin::EndOfStream

CTransformInputPin Class

Informs the input pin that no additional data is expected until a new run command is issued.

HRESULT EndOfStream(void);

Return Values

Returns an HRESULT value.

Remarks

This member function implements the IPin::EndOfStream method. It calls CTransformInputPin::CheckStreaming to see that the filter is in a streaming state and then calls the CTransformFilter::EndOfStream member function.

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CTransformInputPin::NewSegment

CTransformInputPin Class

Specifies that samples following this call are grouped as a segment with a given start time, stop time, and rate.

HRESULT NewSegment(
  REFERENCE_TIME tStart,
  REFERENCE_TIME tStop,
  double dRate
  );

Parameters

tStart

Start time of the segment.

tStop

Stop time of the segment.

dRate

Rate of the segment.

Return Values

Returns an HRESULT value.

Remarks

This member function implements the IPin::NewSegment method and overrides the CBasePin::NewSegment member function. It calls the base class implementation first (CBasePin::NewSegment), and then calls CTransformFilter::NewSegment to pass the notification on to the next filter downstream.

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CTransformInputPin::QueryId

CTransformInputPin Class

Retrieves an identifier for the pin.

HRESULT QueryId(
  LPWSTR * Id
  );

Parameters

Id

Pin identifier.

Return Values

Returns an HRESULT value.

Remarks

This member function implements the IPin::QueryId method and overrides the CBasePin::QueryId member function. It returns the name "In". The caller is responsible for freeing the memory by using the Microsoft® Win32® CoTaskMemFree function.

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CTransformInputPin::Receive

CTransformInputPin Class

Receives the next block of data from the stream.

HRESULT Receive(
  IMediaSample * pSample
  );

Parameters

pSample

Pointer to a media sample.

Return Values

Returns an HRESULT value.

Remarks

This member function implements the IMemInputPin::Receive method. Add a reference to the block of data if access to it is required after the completion of this method. For instance, some decoder filters for temporal compression data streams require that the previous sample be kept in order to decode the current sample.

This member function calls the CTransformFilter::Receive member function, which does the work of calling the transform function and then passing the sample on.

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CTransformInputPin::SetMediaType

CTransformInputPin Class

Informs the derived class when the media type is established for the connection.

HRESULT SetMediaType(
  const CMediaType* mt
  );

Parameters

mt

Pointer to an input media type to be used.

Return Values

Returns an HRESULT value.

Remarks

This member function overrides the CBasePin::SetMediaType member function. It calls the base class CBasePin::SetMediaType member function, which returns NOERROR, and then calls CTransformFilter::SetMediaType, which the derived class can override to be informed when the media type is set.

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