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Step 1: Declare the DShowPlayer Class

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[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

This topic is step 1 of the tutorial Audio/Video Playback in DirectShow. The complete code is shown in the topic DirectShow Playback Example.

In this tutorial, the DShowPlayer class manages all DirectShow functionality. This class is declared as folows.

#include <new>
#include <windows.h>
#include <dshow.h>


enum PlaybackState
{
    STATE_NO_GRAPH,
    STATE_RUNNING,
    STATE_PAUSED,
    STATE_STOPPED,
};

const UINT WM_GRAPH_EVENT = WM_APP + 1;

typedef void (CALLBACK *GraphEventFN)(HWND hwnd, long eventCode, LONG_PTR param1, LONG_PTR param2);

class DShowPlayer
{
public:
    DShowPlayer(HWND hwnd);
    ~DShowPlayer();

    PlaybackState State() const { return m_state; }

    HRESULT OpenFile(PCWSTR pszFileName);
    
    HRESULT Play();
    HRESULT Pause();
    HRESULT Stop();

    BOOL    HasVideo() const;
    HRESULT UpdateVideoWindow(const LPRECT prc);
    HRESULT Repaint(HDC hdc);
    HRESULT DisplayModeChanged();

    HRESULT HandleGraphEvent(GraphEventFN pfnOnGraphEvent);

private:
    HRESULT InitializeGraph();
    void    TearDownGraph();
    HRESULT CreateVideoRenderer();
    HRESULT RenderStreams(IBaseFilter *pSource);

    PlaybackState   m_state;

    HWND m_hwnd; // Video window. This window also receives graph events.

    IGraphBuilder   *m_pGraph;
    IMediaControl   *m_pControl;
    IMediaEventEx   *m_pEvent;
    CVideoRenderer  *m_pVideo;
};

Notes:

  • The PlaybackState enumeration describes the current state of the DShowPlayer object.
  • The constant WM_GRAPH_EVENT defines a private window message. This message is used to notify the application about filter graph events. See Step 6: Handle Graph Events.
  • GraphEventFN is a pointer to a callback function for handling filter graph events. The application implements this callback function.
  • The m_pVideo member variable provides a wrapper for the various DirectShow video renderers. See Step 2: Declare CVideoRenderer and Derived Classes.
  • Throughout this tutorial, the SafeRelease function is used to release COM interface pointers.

Next: Step 2: Declare CVideoRenderer and Derived Classes.

Audio/Video Playback in DirectShow