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Building a VMR-9 Filter Graph

  • Artikkeli

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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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

Because the Video Mixing Renderer 9 Filter (VMR-9) is not the default video renderer, an application that uses the VMR-9 must explicitly add it to the graph and connect it. This section presents two different approaches to building filter graphs with the VMR-9.

Using the Capture Graph Builder

The Capture Graph Builder is a helper object for building custom filter graphs. You can use it to build VMR-9 graphs as follows:

  1. Create and initialize the Capture Graph Builder, as described in the topic About the Capture Graph Builder.

  2. Call CoCreateInstance to create the VMR-9:

    IBaseFilter *pVmr = NULL;
hr = CoCreateInstance(CLSID_VideoMixingRenderer9, 0, 
    CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void**)&pVmr);

  3. Call IFilterGraph::AddFilter on the Filter Graph Manager to add the VMR-9 to the filter graph:

    hr = pGraph->AddFilter(pVmr, L"VMR9");

  4. Call IGraphBuilder::AddSourceFilter to add a source filter for the video file:

    IBaseFilter *pSource;
hr = pGraph->AddSourceFilter(L"C:\\Example.avi", L"Source1", &pSource);

  5. Call the ICaptureGraphBuilder2::RenderStream method to render the video stream to the VMR:

    hr = pBuild->RenderStream(0, 0, pSource, 0, pVmr);

  6. Optionally, call RenderStream again to render the audio stream:

    hr = pBuild->RenderStream(0, &MEDIATYPE_Audio, pSource, 0, NULL);

You can mix several video streams by calling AddSourceFilter and RenderStream for each source file.

Using the Filter Graph Manager

If you prefer not to use the Capture Graph Builder, you can build a VMR-9 graph simply using methods on the Filter Graph Manager, as follows:

  1. Create the VMR-9 and add it to the graph, as shown in the previous procedure.
  2. Use AddSourceFilter to add a source filter for the video file, as shown in the previous procedure.
  3. If you want to render the audio, create an instance of the DirectSound Renderer filter and add it to the filter graph.
  4. Use the IBaseFilter::EnumPins method to find an output pin on the source filter. See Enumerating Pins for details.
  5. Query the Filter Graph Manager for the IFilterGraph2 interface.
  6. Call IFilterGraph2::RenderEx with the AM_RENDEREX_RENDERTOEXISTINGRENDERERS flag. This call renders the output pin, using only the renderer filters already in the graph — in this case, the VMR-9 and the DirectSound Renderer. This prevents the Intelligent Connect logic from adding the default video renderer to the graph, which would leave the VMR-9 unconnected.

Building Graphs with the Capture Graph Builder