使用directshow播放文件并监听事件的简单例子

编者：李国帅

背景原因:

使用directShow进行文件播放，并监听事件。入门例子

播放

Some events are handled silently by the Filter Graph Manager, without the application being notified. Other events are placed on a queue for the application.

#include "stdafx.h"
#include <DShow.h>
 
#pragma comment(lib,"Strmiids.lib")
#pragma comment(lib,"Quartz.lib")
//Strmiids.lib Exports class identifiers (CLSIDs) and interface identifiers (IIDs). All DirectShow applications require this library.
//Quartz.lib Exports the AMGetErrorText function. If you do not call this function, this library is not required.
 
 
int _tmain(int argc, _TCHAR* argv[])
{
// Initialize the COM library.
    HRESULT hr =CoInitialize(NULL);
    if(FAILED(hr))
    {
        printf("ERROR - Could not initialize COM library");
        perror("CoInitialize failed!");
        exit(-1);
    }
// Create the filter graph manager and query for interfaces.
    IGraphBuilder *pGraph =NULL;
    hr = CoCreateInstance(CLSID_FilterGraph,NULL,CLSCTX_INPROC_SERVER,IID_IGraphBuilder,(void **)&pGraph);
    if(FAILED(hr))
    {
        printf("ERROR - Could not create the Filter Graph Manager.");
        perror("IGraphBuilder get failed!");
        CoUninitialize();
        exit(-1);
    }
    IMediaControl *pControl =NULL;
    IMediaEvent *pEvent =NULL;
    hr = pGraph->QueryInterface(IID_IMediaControl,(void**)&pControl);
    hr = pGraph->QueryInterface(IID_IMediaEvent,(void**)&pEvent);
 
// Build the graph. IMPORTANT: Change this string to a file on your system.
    hr = pGraph->RenderFile(L"F:\\Samples\\Media\\chicken_divx.avi",NULL);
    if(SUCCEEDED(hr))
    {
// Run the graph.
        hr = pControl->Run();
        if(SUCCEEDED(hr))
        {
// Wait for completion.
long evCode;
            pEvent->WaitForCompletion(INFINITE,&evCode);
 
// Note: Do not use INFINITE in a real application, because it can block indefinitely.
        }
    }
    if(FAILED(hr))
    {
        perror("RenderFile failed!");
        pGraph->Release();
        CoUninitialize();
        exit(-1);
    }
 
    pControl->Release();
    pEvent->Release();
    pGraph->Release();
    CoUninitialize();
 
    return 0;
}

使用窗口句柄接收事件

#define WM_GRAPHNOTIFY  WM_APP + 1
IMediaEventEx *g_pEvent =NULL;
 
pGraph->QueryInterface(IID_IMediaEventEx,(void **)&g_pEvent);
g_pEvent->SetNotifyWindow((OAHWND)g_hwnd, WM_GRAPHNOTIFY, 0);
 
//In your application's WindowProc function, add a case statement for the WM_GRAPHNOTIFY message:
case WM_GRAPHNOTIFY:    HandleGraphEvent();break;
void HandleGraphEvent()
{
// Disregard if we don't have an IMediaEventEx pointer.
    if(g_pEvent ==NULL)return;
 
// Get all the events
long evCode, param1, param2;
    HRESULT hr;
    while(SUCCEEDED(g_pEvent->GetEvent(&evCode,¶m1,¶m2, 0)))
    {
        g_pEvent->FreeEventParams(evCode, param1, param2);
        switch(evCode)
        {
        case EC_COMPLETE:  // Fall through.
        case EC_USERABORT: // Fall through.
        case EC_ERRORABORT:
            CleanUp();
            PostQuitMessage(0);
            return;
        }
    }
}
 
// Disable event notification before releasing the graph.
g_pEvent->SetNotifyWindow(NULL, 0, 0);
g_pEvent->Release();
g_pEvent =NULL;