//------------------------------------------------------------------------------
// File: Transfrm.h
//
// Desc: DirectShow base classes - defines classes from which simple 
//       transform codecs may be derived.
//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//------------------------------------------------------------------------------

// It assumes the codec has one input and one output stream, and has no
// interest in memory management, interface negotiation or anything else.
//
// derive your class from this, and supply Transform and the media type/format
// negotiation functions. Implement that class, compile and link and
// you're done.

ifndef __TRANSFRM__
define __TRANSFRM__

// ======================================================================
// This is the com object that represents a simple transform filter. It
// supports IBaseFilter, IMediaFilter and two pins through nested interfaces
// ======================================================================

class CTransformFilter;

// ==================================================
// Implements the input pin
// ==================================================

  class CTransformInputPin : public CBaseInputPin
{
    friend

CTransformFilter;</h4>

---

   class CTransformFilter;
  
  protected:
      CTransformFilter *m_pTransformFilter;
  
  public:
  
      CTransformInputPin(
          TCHAR *pObjectName,
          CTransformFilter *pTransformFilter,
          HRESULT * phr,
          LPCWSTR pName);
  ifdef UNICODE
      CTransformInputPin(
          char *pObjectName,
          CTransformFilter *pTransformFilter,
          HRESULT * phr,
          LPCWSTR pName);
  endif
  
      STDMETHODIMP QueryId(LPWSTR * Id)
      {
          return AMGetWideString(L"In", Id);
      }
  
      // Grab and release extra interfaces if required
  
      HRESULT CheckConnect(IPin *pPin);
      HRESULT BreakConnect();
      HRESULT CompleteConnect(IPin *pReceivePin);
  
      // check that we can support this output type
      HRESULT CheckMediaType(const CMediaType* mtIn);
  
      // set the connection media type
      HRESULT SetMediaType(const CMediaType* mt);
  
      // --- IMemInputPin -----
  
      // here's the next block of data from the stream.
      // AddRef it yourself if you need to hold it beyond the end
      // of this call.
      STDMETHODIMP Receive(IMediaSample * pSample);
  
      // provide EndOfStream that passes straight downstream
      // (there is no queued data)
      STDMETHODIMP EndOfStream(void);
  
      // passes it to CTransformFilter::BeginFlush
      STDMETHODIMP BeginFlush(void);
  
      // passes it to CTransformFilter::EndFlush
      STDMETHODIMP EndFlush(void);
  
      STDMETHODIMP NewSegment(
                          REFERENCE_TIME tStart,
                          REFERENCE_TIME tStop,
                          double dRate);
  
      // Check if it's OK to process samples
      virtual HRESULT CheckStreaming();
  
      // Media type
  public:
      CMediaType& CurrentMediaType() { return m_mt; };

---

  
  };

---

  
  // ==================================================
  // Implements the output pin
  // ==================================================
  
  

---

CTransformOutputPin</h4>

---

  class CTransformOutputPin : public CBaseOutputPin
  {
      friend

---

CTransformFilter;</h4>

---

   class CTransformFilter;
  
  protected:
      CTransformFilter *m_pTransformFilter;
  
  public:
  
      // implement IMediaPosition by passing upstream
      IUnknown * m_pPosition;
  
      CTransformOutputPin(
          TCHAR *pObjectName,
          CTransformFilter *pTransformFilter,
          HRESULT * phr,
          LPCWSTR pName);
  ifdef UNICODE
      CTransformOutputPin(
          CHAR *pObjectName,
          CTransformFilter *pTransformFilter,
          HRESULT * phr,
          LPCWSTR pName);
  endif
      ~CTransformOutputPin();
  
      // override to expose IMediaPosition
      STDMETHODIMP NonDelegatingQueryInterface(REFIID riid, void **ppv);
  
      // --- CBaseOutputPin ------------
  
      STDMETHODIMP QueryId(LPWSTR * Id)
      {
          return AMGetWideString(L"Out", Id);
      }
  
      // Grab and release extra interfaces if required
  
      HRESULT CheckConnect(IPin *pPin);
      HRESULT BreakConnect();
      HRESULT CompleteConnect(IPin *pReceivePin);
  
      // check that we can support this output type
      HRESULT CheckMediaType(const CMediaType* mtOut);
  
      // set the connection media type
      HRESULT SetMediaType(const CMediaType *pmt);
  
      // called from CBaseOutputPin during connection to ask for
      // the count and size of buffers we need.
      HRESULT DecideBufferSize(
                  IMemAllocator * pAlloc,
                  ALLOCATOR_PROPERTIES *pProp);
  
      // returns the preferred formats for a pin
      HRESULT GetMediaType(int iPosition,CMediaType *pMediaType);
  
      // inherited from IQualityControl via CBasePin
      STDMETHODIMP Notify(IBaseFilter * pSender, Quality q);
  
      // Media type
  public:
      CMediaType& CurrentMediaType() { return m_mt; };

---

  };

---

---

AM_NOVTABLE</h4>

---

  class AM_NOVTABLE CTransformFilter : public CBaseFilter
  {
  
  public:
  
      // map getpin/getpincount for base enum of pins to owner
      // override this to return more specialised pin objects
  
      virtual int GetPinCount();
      virtual CBasePin * GetPin(int n);
      STDMETHODIMP FindPin(LPCWSTR Id, IPin **ppPin);
  
      // override state changes to allow derived transform filter
      // to control streaming start/stop
      STDMETHODIMP Stop();
      STDMETHODIMP Pause();
  
  public:
  
      CTransformFilter(TCHAR *, LPUNKNOWN, REFCLSID clsid);
  ifdef UNICODE
      CTransformFilter(CHAR *, LPUNKNOWN, REFCLSID clsid);
  endif
      ~CTransformFilter();
  
      // =================================================================
      // ----- override these bits ---------------------------------------
      // =================================================================
  
      // These must be supplied in a derived class
  
      virtual HRESULT Transform(IMediaSample * pIn, IMediaSample *pOut);
  
      // check if you can support mtIn
      virtual HRESULT CheckInputType(const CMediaType* mtIn) PURE;
  
      // check if you can support the transform from this input to this output
      virtual HRESULT CheckTransform(const CMediaType* mtIn, const CMediaType* mtOut) PURE;
  
      // this goes in the factory template table to create new instances
      // static CCOMObject * CreateInstance(LPUNKNOWN, HRESULT *);
  
      // call the SetProperties function with appropriate arguments
      virtual HRESULT DecideBufferSize(
                          IMemAllocator * pAllocator,
                          ALLOCATOR_PROPERTIES *pprop) PURE;
  
      // override to suggest OUTPUT pin media types
      virtual HRESULT GetMediaType(int iPosition, CMediaType *pMediaType) PURE;
  
      // =================================================================
      // ----- Optional Override Methods           -----------------------
      // =================================================================
  
      // you can also override these if you want to know about streaming
      virtual HRESULT StartStreaming();
      virtual HRESULT StopStreaming();
  
      // override if you can do anything constructive with quality notifications
      virtual HRESULT AlterQuality(Quality q);
  
      // override this to know when the media type is actually set
      virtual HRESULT SetMediaType(PIN_DIRECTION direction,const CMediaType *pmt);
  
      // chance to grab extra interfaces on connection
      virtual HRESULT CheckConnect(PIN_DIRECTION dir,IPin *pPin);
      virtual HRESULT BreakConnect(PIN_DIRECTION dir);
      virtual HRESULT CompleteConnect(PIN_DIRECTION direction,IPin *pReceivePin);
  
      // chance to customize the transform process
      virtual HRESULT Receive(IMediaSample *pSample);
  
      // Standard setup for output sample
      HRESULT InitializeOutputSample(IMediaSample *pSample, IMediaSample **ppOutSample);
  
      // if you override Receive, you may need to override these three too
      virtual HRESULT EndOfStream(void);
      virtual HRESULT BeginFlush(void);
      virtual HRESULT EndFlush(void);
      virtual HRESULT NewSegment(
                          REFERENCE_TIME tStart,
                          REFERENCE_TIME tStop,
                          double dRate);
  
  ifdef PERF
      // Override to register performance measurement with a less generic string
      // You should do this to avoid confusion with other filters
      virtual void RegisterPerfId()
           {m_idTransform = MSR_REGISTER(TEXT("Transform"));}
  endif // PERF
  
  // implementation details
  
  protected:
  
  ifdef PERF
      int m_idTransform;                 // performance measuring id
  endif
      BOOL m_bEOSDelivered;              // have we sent EndOfStream
      BOOL m_bSampleSkipped;             // Did we just skip a frame
      BOOL m_bQualityChanged;            // Have we degraded?
  
      // critical section protecting filter state.
  
      CCritSec m_csFilter;
  
      // critical section stopping state changes (ie Stop) while we're
      // processing a sample.
      //
      // This critical section is held when processing
      // events that occur on the receive thread - Receive() and EndOfStream().
      //
      // If you want to hold both m_csReceive and m_csFilter then grab
      // m_csFilter FIRST - like CTransformFilter::Stop() does.
  
      CCritSec m_csReceive;
  
      // these hold our input and output pins
  
      friend

---

CTransformInputPin;</h4>

---

   class CTransformInputPin;
      friend

---

CTransformOutputPin;</h4>

---

   class CTransformOutputPin;
      CTransformInputPin *m_pInput;
      CTransformOutputPin *m_pOutput;
  };
  
  endif /* __TRANSFRM__ */
  
  

---

[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

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(C) Æliens 20/2/2008

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