strmctl.h

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//------------------------------------------------------------------------------
// File: StrmCtl.h
//
// Desc: DirectShow base classes.
//
// Copyright (c) 1996-2001 Microsoft Corporation.  All rights reserved.
//------------------------------------------------------------------------------
 
 
#ifndef __strmctl_h__
#define __strmctl_h__
 
class CBaseStreamControl : public IAMStreamControl
{
public:
    // Used by the implementation
    enum StreamControlState
    { STREAM_FLOWING = 0x1000,
      STREAM_DISCARDING
    };
 
private:
    enum StreamControlState m_StreamState;      // Current stream state
    enum StreamControlState m_StreamStateOnStop;    // State after next stop
                        // (i.e.Blocking or Discarding)
 
    REFERENCE_TIME  m_tStartTime;       // MAX_TIME implies none
    REFERENCE_TIME  m_tStopTime;        // MAX_TIME implies none
    DWORD       m_dwStartCookie;    // Cookie for notification to app
    DWORD       m_dwStopCookie;     // Cookie for notification to app
    volatile BOOL       m_bIsFlushing;        // No optimization pls!
    volatile BOOL   m_bStopSendExtra;   // bSendExtra was set
    volatile BOOL   m_bStopExtraSent;   // the extra one was sent
 
    CCritSec        m_CritSec;      // CritSec to guard above attributes
 
    // Event to fire when we can come
    // out of blocking, or to come out of waiting
    // to discard if we change our minds.
    //
    CAMEvent            m_StreamEvent;
 
    // All of these methods execute immediately.  Helpers for others.
    //
    void ExecuteStop();
    void ExecuteStart();
    void CancelStop();
    void CancelStart();
 
    // Some things we need to be told by our owning filter
    // Your pin must also expose IAMStreamControl when QI'd for it!
    //
    IReferenceClock *   m_pRefClock;        // Need it to set advises
                        // Filter must tell us via
                        // SetSyncSource
    IMediaEventSink *   m_pSink;            // Event sink
                        // Filter must tell us after it
                        // creates it in JoinFilterGraph()
    FILTER_STATE    m_FilterState;      // Just need it!
                        // Filter must tell us via
                        // NotifyFilterState
    REFERENCE_TIME  m_tRunStart;        // Per the Run call to the filter
 
    // This guy will return one of the three StreamControlState's.  Here's what
    // the caller should do for each one:
    //
    // STREAM_FLOWING:      Proceed as usual (render or pass the sample on)
    // STREAM_DISCARDING:   Calculate the time 'til *pSampleStop and wait
    //              that long for the event handle
    //              (GetStreamEventHandle()).  If the wait
    //              expires, throw the sample away.  If the event
    //              fires, call me back - I've changed my mind.
    //
    enum StreamControlState CheckSampleTimes( __in const REFERENCE_TIME * pSampleStart,
                          __in const REFERENCE_TIME * pSampleStop );
 
public:
    // You don't have to tell us much when we're created, but there are other
    // obligations that must be met.  See SetSyncSource & NotifyFilterState
    // below.
    //
    CBaseStreamControl(__inout_opt HRESULT *phr = NULL);
    ~CBaseStreamControl();
 
    // If you want this class to work properly, there are thing you need to
    // (keep) telling it.  Filters with pins that use this class
    // should ensure that they pass through to this method any calls they
    // receive on their SetSyncSource.
 
    // We need a clock to see what time it is.  This is for the
    // "discard in a timely fashion" logic.  If we discard everything as
    // quick as possible, a whole 60 minute file could get discarded in the
    // first 10 seconds, and if somebody wants to turn streaming on at 30 
    // minutes into the file, and they make the call more than a few seconds
    // after the graph is run, it may be too late!
    // So we hold every sample until it's time has gone, then we discard it.
    // The filter should call this when it gets a SetSyncSource
    //
    void SetSyncSource( IReferenceClock * pRefClock )
    {
    CAutoLock lck(&m_CritSec);
    if (m_pRefClock) m_pRefClock->Release();
    m_pRefClock = pRefClock;
    if (m_pRefClock) m_pRefClock->AddRef();
    }
 
    // Set event sink for notifications
    // The filter should call this in its JoinFilterGraph after it creates the
    // IMediaEventSink
    //
    void SetFilterGraph( IMediaEventSink *pSink ) {
        m_pSink = pSink;
    }
 
    // Since we schedule in stream time, we need the tStart and must track the
    // state of our owning filter.
    // The app should call this ever state change
    //
    void NotifyFilterState( FILTER_STATE new_state, REFERENCE_TIME tStart = 0 );
 
    // Filter should call Flushing(TRUE) in BeginFlush,
    // and Flushing(FALSE) in EndFlush.
    //
    void Flushing( BOOL bInProgress );
 
 
    // The two main methods of IAMStreamControl
 
    // Class adds default values suitable for immediate
    // muting and unmuting of the stream.
 
    STDMETHODIMP StopAt( const REFERENCE_TIME * ptStop = NULL,
             BOOL bSendExtra = FALSE,
             DWORD dwCookie = 0 );
    STDMETHODIMP StartAt( const REFERENCE_TIME * ptStart = NULL,
                  DWORD dwCookie = 0 );
    STDMETHODIMP GetInfo( __out AM_STREAM_INFO *pInfo);
 
    // Helper function for pin's receive method.  Call this with
    // the sample and we'll tell you what to do with it.  We'll do a
    // WaitForSingleObject within this call if one is required.  This is
    // a "What should I do with this sample?" kind of call. We'll tell the
    // caller to either flow it or discard it.
    // If pSample is NULL we evaluate based on the current state
    // settings
    enum StreamControlState CheckStreamState( IMediaSample * pSample );
 
private:
    // These don't require locking, but we are relying on the fact that
    // m_StreamState can be retrieved with integrity, and is a snap shot that
    // may have just been, or may be just about to be, changed.
    HANDLE GetStreamEventHandle() const { return m_StreamEvent; }
    enum StreamControlState GetStreamState() const { return m_StreamState; }
    BOOL IsStreaming() const { return m_StreamState == STREAM_FLOWING; }
};
 
#endif