Directshow_播放一個文件

Directshow_播放一個文件

1.初始化

	HRESULT hr = CoInitialize(NULL);
	if (FAILED(hr))
	{
		// Add error-handling code here. (Omitted for clarity.)
	}

2.創建圖表管理器

	IGraphBuilder *pGraph;
HRESULT hr = CoCreateInstance(CLSID_FilterGraph, NULL, 
    CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void **)&pGraph);
    if (FAILED(hr))
	{
		// Add error-handling code here. (Omitted for clarity.)
	}

3.創建控制器和事件

IMediaControl *pControl;
IMediaEvent   *pEvent;
hr = pGraph->QueryInterface(IID_IMediaControl, (void **)&pControl);
hr = pGraph->QueryInterface(IID_IMediaEvent, (void **)&pEvent);

4.準備讀取的文件

//輸入存在的文件路徑 進行讀取
hr = pGraph->RenderFile(L"D:\\Example.avi", NULL);

5.開始讀取

hr = pControl->Run();

當開啓時，directshow會自動鏈接所有需要的Filter，然後進行渲染。

6.事件等待

long evCode = 0;
pEvent->WaitForCompletion(INFINITE, &evCode);

作用：等待文件播放完成，阻塞後續程序的執行。

7.釋放資源

	pControl->Release();
	pEvent->Release();
	pGraph->Release();
	CoUninitialize();

完整的代碼

#include <dshow.h>
#pragma comment (lib,"Strmiids.lib")
#pragma comment (lib,"Quartz.lib")
void main(void)
{
    IGraphBuilder *pGraph = NULL;
    IMediaControl *pControl = NULL;
    IMediaEvent   *pEvent = NULL;

    // Initialize the COM library.
    HRESULT hr = CoInitialize(NULL);
    if (FAILED(hr))
    {
        printf("ERROR - Could not initialize COM library");
        return;
    }

    // Create the filter graph manager and query for interfaces.
    hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, 
                        IID_IGraphBuilder, (void **)&pGraph);
    if (FAILED(hr))
    {
        printf("ERROR - Could not create the Filter Graph Manager.");
        return;
    }

    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"D:\\Example.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.
        }
    }
    pControl->Release();
    pEvent->Release();
    pGraph->Release();
    CoUninitialize();
}