[DirectShow] 列舉出接受管理的 Filters 資訊 -- IEnumFilters

使用 intelligent connection 連接後面的 Filters 是很方便的作法, 尤其是你不想寫程式的時候, intelligent 是上天送給你的禮物.

但是, 當你在寫 DirectShow 程式專案時, Bugs就像是鬼魅般地一直糾纏著你, 卻找不到任何蛛絲馬跡.

特別是裝了 K-Lite package 或其他一堆 Filters 時, multi-thread 的同步問題以及 timing 的問題已經夠棘手了, 別又告訴我 xvid.ax 與 ffmpeg filters 之間的程式行為有所不同 (他們確實不同!).

知道你應用程式中負責處理的 Filters 資訊就很重要. 專注一個 Filter 然後, 再解決另一個 filter 的問題. 應該是解決問題的方法.

When you are debugging in a DirectShow project, these information are crucial that determine what time you can go home.

Enumerating DirectShow filters!

I need this for a long time. To get the job done, you can use IEnumFilters to enumerate the filters in your program.

How to use? The detail is listed as follows.

-------------------------------- code ------------------------------

#include <streams.h>

// 印出 Grpah Manager中管理的所有 Filters 名稱
HRESULT PrintAllFilter(IGraphBuilder *pGB){
    HRESULT hr;
    CComPtr<IEnumFilters> pEnum = NULL;
    IBaseFilter *pFilter = NULL;
    IPin *pPin;
    ULONG ulFetched;

    // Verify graph builder interface
    if (!pGB)
        return E_NOINTERFACE;

    // Get filter enumerator
    hr = pGB->EnumFilters(&pEnum);
    if (FAILED(hr))
        return hr;

    pEnum->Reset();

     // Enumerate all filters in the graph
    while((pEnum->Next(1, &pFilter, &ulFetched) == S_OK)){
       // Read filter name for debugging purposes
        FILTER_INFO FilterInfo;
        TCHAR szName[256];
        hr = pFilter->QueryFilterInfo(&FilterInfo);
        if (SUCCEEDED(hr)){
            // Show filter name 
            lstrcpyn(szName, FilterInfo.achName, 256);  
            FilterInfo.pGraph->Release();
        }

        pFilter->Release();

        TRACE(_T("Filter name=%s\n"),szName);
        szName[255] = 0;        // Null-terminate

    } 
      return hr;
}

-------------------------------- end of code --------------------------

Based on this code, I can exactly understand what filters is plugged in my programming. If you don't like program, you can use graphedit.exe to do the same thing.

 

Enjoy.

by Jing