baseclass.pas

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    // fail). After calling this, you need to free any queued data
    // and then call downstream.
    function BeginFlush: HRESULT; override; stdcall;

    // default handling for EndFlush - call at end of your implementation
    // - before calling this, ensure that there is no queued data and no thread
    // pushing any more without a further receive, then call downstream,
    // then call this method to clear the m_bFlushing flag and re-enable
    // receives
    function EndFlush: HRESULT; override; stdcall;

    // Release the pin's allocator.
    function BreakConnect: HRESULT; override;

    // helper method to check the read-only flag
    property IsReadOnly: boolean read FReadOnly;

    // helper method to see if we are flushing
    property IsFlushing: boolean read FFlushing;

    //  Override this for checking whether it's OK to process samples
    //  Also call this from EndOfStream.
    function CheckStreaming: HRESULT; virtual;

    // Pass a Quality notification on to the appropriate sink
    function PassNotify(const q: TQuality): HRESULT;


    //================================================================================
    // IQualityControl methods (from CBasePin)
    //================================================================================

    function Notify(pSelf: IBaseFilter; q: TQuality): HRESULT; override; stdcall;

    // no need to override:
    // STDMETHODIMP SetSink(IQualityControl * piqc);

    // switch the pin to inactive state - may already be inactive
    function Inactive: HRESULT; override;

    // Return sample properties pointer
    function SampleProps: PAMSample2Properties;
  end;

// milenko start (added TBCDynamicOutputPin conversion)
  TBLOCK_STATE = (NOT_BLOCKED, PENDING, BLOCKED);

  TBCDynamicOutputPin = class(TBCBaseOutputPin, IPinFlowControl)
  public
    constructor Create(ObjectName: WideString; Filter: TBCBaseFilter;
                       Lock: TBCCritSec; out hr: HRESULT; Name: WideString);
    destructor Destroy; override;
    // IUnknown Methods
    function NonDelegatingQueryInterface(const IID: TGUID; out Obj): HResult; override;
    // IPin Methods
    function Disconnect: HRESULT; override; stdcall;
    // IPinFlowControl Methods
    function Block(dwBlockFlags: DWORD; hEvent: THandle): HResult; stdcall;
    //  Set graph config info
    procedure SetConfigInfo(GraphConfig: IGraphConfig; StopEvent: THandle);
    {$IFDEF DEBUG}
    function Deliver(Sample: IMediaSample): HRESULT; override;
    function DeliverEndOfStream: HRESULT; override;
    function DeliverNewSegment(Start, Stop: TReferenceTime; Rate: double): HRESULT; override;
    {$ENDIF} // DEBUG
    function DeliverBeginFlush: HRESULT; override;
    function DeliverEndFlush: HRESULT; override;
    function Active: HRESULT; override;
    function Inactive: HRESULT; override;
    function CompleteConnect(ReceivePin: IPin): HRESULT; override;
    function StartUsingOutputPin: HRESULT; virtual;
    procedure StopUsingOutputPin; virtual;
    function StreamingThreadUsingOutputPin: Boolean; virtual;
    function ChangeOutputFormat(const pmt: PAMMediaType; tSegmentStart, tSegmentStop:
                                TreferenceTime; dSegmentRate: Double): HRESULT;
    function ChangeMediaType(const pmt: PAMMEdiaType): HRESULT;
    function DynamicReconnect(const pmt: PAMMediaType): HRESULT;
  protected
    // This lock should be held when the following class members are
    // being used: m_hNotifyCallerPinBlockedEvent, m_BlockState,
    // m_dwBlockCallerThreadID and m_dwNumOutstandingOutputPinUsers.
    FBlockStateLock: TBCCritSec;
    // This event should be signaled when the output pin is
    // not blocked.  This is a manual reset event.  For more
    // information on events, see the documentation for
    // CreateEvent() in the Windows SDK.
    FUnblockOutputPinEvent: THandle;
    // This event will be signaled when block operation succeedes or
    // when the user cancels the block operation.  The block operation
    // can be canceled by calling IPinFlowControl2::Block( 0, NULL )
    // while the block operation is pending.
    FNotifyCallerPinBlockedEvent: THandle;
    // The state of the current block operation.
    FBlockState: TBLOCK_STATE;
    // The ID of the thread which last called IPinFlowControl::Block().
    // For more information on thread IDs, see the documentation for
    // GetCurrentThreadID() in the Windows SDK.
    FBlockCallerThreadID: DWORD;
    // The number of times StartUsingOutputPin() has been sucessfully
    // called and a corresponding call to StopUsingOutputPin() has not
    // been made.  When this variable is greater than 0, the streaming
    // thread is calling IPin::NewSegment(), IPin::EndOfStream(),
    // IMemInputPin::Receive() or IMemInputPin::ReceiveMultiple().  The
    // streaming thread could also be calling: DynamicReconnect(),
    // ChangeMediaType() or ChangeOutputFormat().  The output pin cannot
    // be blocked while the output pin is being used.
    FNumOutstandingOutputPinUsers: DWORD;
    // This event should be set when the IMediaFilter::Stop() is called.
    // This is a manual reset event.  It is also set when the output pin
    // delivers a flush to the connected input pin.
    FStopEvent: THandle;
    FGraphConfig: IGraphConfig;
    // TRUE if the output pin's allocator's samples are read only.
    // Otherwise FALSE.  For more information, see the documentation
    // for IMemInputPin::NotifyAllocator().
    FPinUsesReadOnlyAllocator: Boolean;
    function SynchronousBlockOutputPin: HRESULT;
    function AsynchronousBlockOutputPin(NotifyCallerPinBlockedEvent: THandle): HRESULT;
    function UnblockOutputPin: HRESULT;
    procedure BlockOutputPin;
    procedure ResetBlockState;
    class function WaitEvent(Event: THandle): HRESULT;
  private
    function Initialize: HRESULT;
    function ChangeMediaTypeHelper(const pmt: PAMMediaType): HRESULT;
    {$IFDEF DEBUG}
    procedure AssertValid;
    {$ENDIF} // DEBUG
  end;
// milenko end

  TBCTransformOutputPin = class;
  TBCTransformInputPin  = class;

  TBCTransformFilter = class(TBCBaseFilter)
  protected
    FEOSDelivered  : boolean; // have we sent EndOfStream
    FSampleSkipped : boolean; // Did we just skip a frame
    FQualityChanged: boolean; // Have we degraded?
    // critical section protecting filter state.
    FcsFilter: TBCCritSec;
    // 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.
    FcsReceive: TBCCritSec;
    // these hold our input and output pins
    FInput : TBCTransformInputPin;
    FOutput: TBCTransformOutputPin;
  public
    // map getpin/getpincount for base enum of pins to owner
    // override this to return more specialised pin objects

    function GetPinCount: integer; override;
    function GetPin(n: integer): TBCBasePin; override;
    function FindPin(Id: PWideChar; out ppPin: IPin): HRESULT; override; stdcall;

    // override state changes to allow derived transform filter
    // to control streaming start/stop
    function Stop: HRESULT; override; stdcall;
    function Pause: HRESULT; override; stdcall;

    constructor Create(ObjectName: string; unk: IUnKnown; const clsid: TGUID);
    constructor CreateFromFactory(Factory: TBCClassFactory; const Controller: IUnknown); override;
    destructor destroy; override;

    // =================================================================
    // ----- override these bits ---------------------------------------
    // =================================================================

    // These must be supplied in a derived class
    function Transform(msIn, msout: IMediaSample): HRESULT; virtual;

    // check if you can support mtIn
    function CheckInputType(mtIn: PAMMediaType): HRESULT; virtual; abstract;

    // check if you can support the transform from this input to this output
    function CheckTransform(mtIn, mtOut: PAMMediaType): HRESULT; virtual; abstract;

    // this goes in the factory template table to create new instances
    // static CCOMObject * CreateInstance(LPUNKNOWN, HRESULT *);

    // call the SetProperties function with appropriate arguments
    function DecideBufferSize(Allocator: IMemAllocator; prop: PAllocatorProperties): HRESULT; virtual; abstract;

    // override to suggest OUTPUT pin media types
    function GetMediaType(Position: integer; out MediaType: PAMMediaType): HRESULT; virtual; abstract;



    // =================================================================
    // ----- Optional Override Methods           -----------------------
    // =================================================================

    // you can also override these if you want to know about streaming
    function StartStreaming: HRESULT; virtual;
    function StopStreaming: HRESULT; virtual;

    // override if you can do anything constructive with quality notifications
    function AlterQuality(const q: TQuality): HRESULT; virtual;

    // override this to know when the media type is actually set
    function SetMediaType(direction: TPinDirection; pmt: PAMMediaType): HRESULT; virtual;

    // chance to grab extra interfaces on connection
    function CheckConnect(dir: TPinDirection; Pin: IPin): HRESULT; virtual;
    function BreakConnect(dir: TPinDirection): HRESULT; virtual;
    function CompleteConnect(direction: TPinDirection; ReceivePin: IPin): HRESULT; virtual;

    // chance to customize the transform process
    function Receive(Sample: IMediaSample): HRESULT; virtual;

    // Standard setup for output sample
    function InitializeOutputSample(Sample: IMediaSample; out OutSample: IMediaSample): HRESULT; virtual;

    // if you override Receive, you may need to override these three too
    function EndOfStream: HRESULT; virtual;
    function BeginFlush: HRESULT; virtual;
    function EndFlush: HRESULT; virtual;
    function NewSegment(Start, Stop: TReferenceTime; Rate: double): HRESULT; virtual;

    property Input: TBCTransformInputPin read FInput write FInput;
    property Output: TBCTransformOutputPin read FOutPut write FOutput;

  end;

  TBCTransformInputPin = class(TBCBaseInputPin)
  private
    FTransformFilter: TBCTransformFilter;
  public
    constructor Create(ObjectName: string; TransformFilter: TBCTransformFilter;
      out hr: HRESULT; Name: WideString);

    destructor destroy; override;
    function QueryId(out id: PWideChar): HRESULT; override; stdcall;


    // Grab and release extra interfaces if required

    function CheckConnect(Pin: IPin): HRESULT; override;
    function BreakConnect: HRESULT; override;
    function CompleteConnect(ReceivePin: IPin): HRESULT; override;

    // check that we can support this output type
    function CheckMediaType(mtIn: PAMMediaType): HRESULT; override;

    // set the connection media type
    function SetMediaType(mt: PAMMediaType): HRESULT; override;

    // --- 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.
    function Receive(pSample: IMediaSample): HRESULT; override; stdcall;

    // provide EndOfStream that passes straight downstream
    // (there is no queued data)
    function EndOfStream: HRESULT; override; stdcall;

    // passes it to CTransformFilter::BeginFlush
    function BeginFlush: HRESULT; override; stdcall;

    // passes it to CTransformFilter::EndFlush
    function EndFlush: HRESULT; override; stdcall;

    function NewSegment(Start, Stop: TReferenceTime; Rate: double): HRESULT; override; stdcall;

    // Check if it's OK to process samples
    function CheckStreaming: HRESULT; override;
  end;

  TBCTransformOutputPin = class(TBCBaseOutputPin)
  protected
    FTransformFilter: TBCTransformFilter;
    // implement IMediaPosition by passing upstream
    FPosition: IUnknown;
  public
    constructor Create(ObjectName: string; TransformFilter: TBCTransformFilter;
      out hr: HRESULT; Name: WideString);
    destructor destroy; override;
    // override to expose IMediaPosition
    function NonDelegatingQueryInterface(const IID: TGUID; out Obj): HResult; override;