Creating Source Nodes

A source node represents one stream from a media source. The source node must contain pointers to the media source, the presentation descriptor, and the stream descriptor.

To add a source node to a topology, do the following:

  1. Call MFCreateTopologyNode with the MF_TOPOLOGY_SOURCESTREAM_NODE flag to create the source node.
  2. Set the MF_TOPONODE_SOURCE attribute on the node, with a pointer to the media source.
  3. Set the MF_TOPONODE_PRESENTATION_DESCRIPTOR attribute on the node, with a pointer to the presentation descriptor of the media source.
  4. Set the MF_TOPONODE_STREAM_DESCRIPTOR attribute on the node, with a pointer to the stream descriptor for the stream.
  5. Call IMFTopology::AddNode to add the node to the topology.

The following example creates and initializes a source node.


// Add a source node to a topology.
HRESULT AddSourceNode(
    IMFTopology *pTopology,           // Topology.
    IMFMediaSource *pSource,          // Media source.
    IMFPresentationDescriptor *pPD,   // Presentation descriptor.
    IMFStreamDescriptor *pSD,         // Stream descriptor.
    IMFTopologyNode **ppNode)         // Receives the node pointer.
{
    IMFTopologyNode *pNode = NULL;

    // Create the node.
    HRESULT hr = MFCreateTopologyNode(MF_TOPOLOGY_SOURCESTREAM_NODE, &pNode);
    if (FAILED(hr))
    {
        goto done;
    }

    // Set the attributes.
    hr = pNode->SetUnknown(MF_TOPONODE_SOURCE, pSource);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pNode->SetUnknown(MF_TOPONODE_PRESENTATION_DESCRIPTOR, pPD);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pNode->SetUnknown(MF_TOPONODE_STREAM_DESCRIPTOR, pSD);
    if (FAILED(hr))
    {
        goto done;
    }
    
    // Add the node to the topology.
    hr = pTopology->AddNode(pNode);
    if (FAILED(hr))
    {
        goto done;
    }

    // Return the pointer to the caller.
    *ppNode = pNode;
    (*ppNode)->AddRef();

done:
    SafeRelease(&pNode);
    return hr;
}


Related topics

Creating Topologies
Media Sources
Topologies
IMFTopologyNode

 

 

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