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