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Saving a Filter Graph to a GraphEdit File

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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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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.]

The following code example shows how to save a filter graph to a GraphEdit (.grf) file. This can be useful for debugging your applications.

HRESULT SaveGraphFile(IGraphBuilder *pGraph, WCHAR *wszPath) 
{
    const WCHAR wszStreamName[] = L"ActiveMovieGraph"; 
    HRESULT hr;
    
    IStorage *pStorage = NULL;
    hr = StgCreateDocfile(
        wszPath,
        STGM_CREATE | STGM_TRANSACTED | STGM_READWRITE | STGM_SHARE_EXCLUSIVE,
        0, &pStorage);
    if(FAILED(hr)) 
    {
        return hr;
    }

    IStream *pStream;
    hr = pStorage->CreateStream(
        wszStreamName,
        STGM_WRITE | STGM_CREATE | STGM_SHARE_EXCLUSIVE,
        0, 0, &pStream);
    if (FAILED(hr)) 
    {
        pStorage->Release();    
        return hr;
    }

    IPersistStream *pPersist = NULL;
    pGraph->QueryInterface(IID_IPersistStream, (void**)&pPersist);
    hr = pPersist->Save(pStream, TRUE);
    pStream->Release();
    pPersist->Release();
    if (SUCCEEDED(hr)) 
    {
        hr = pStorage->Commit(STGC_DEFAULT);
    }
    pStorage->Release();
    return hr;
}

For example, the following code builds a file playback graph and saves it to a file named MyGraph.grf:

void __cdecl main(void)
{
    HRESULT hr;
    IGraphBuilder *pGraph;
    CoInitialize(NULL);
    
    // Create the Filter Graph Manager and render a file.
    CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, 
        IID_IGraphBuilder, reinterpret_cast<void**>(&pGraph));
    hr = pGraph->RenderFile(L"C:\\Video.avi", NULL);

    if (SUCCEEDED(hr))
    {
        hr = SaveGraphFile(pGraph, L"C:\\MyGraph.grf");
    }
    
    pGraph->Release();
    CoUninitialize();
}

Simulating Graph Building with GraphEdit

StgCreateDocfile