IMFTopoLoader::Load method (mfidl.h)

Article
10/13/2021

Creates a fully loaded topology from the input partial topology.

Syntax

HRESULT Load(
  [in]  IMFTopology *pInputTopo,
  [out] IMFTopology **ppOutputTopo,
  [in]  IMFTopology *pCurrentTopo
);

Parameters

[in] pInputTopo

A pointer to the IMFTopology interface of the partial topology to be resolved.

[out] ppOutputTopo

Receives a pointer to the IMFTopology interface of the completed topology. The caller must release the interface.

[in] pCurrentTopo

A pointer to the IMFTopology interface of the previous full topology. The topology loader can re-use objects from this topology in the new topology. This parameter can be NULL. See Remarks.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code	Description
S_OK	The method succeeded.
MF_E_TOPO_SINK_ACTIVATES_UNSUPPORTED	One or more output nodes contain IMFActivate pointers. The caller must bind the output nodes to media sinks. See Binding Output Nodes to Media Sinks.

Remarks

This method creates any intermediate transforms that are needed to complete the topology. It also sets the input and output media types on all of the objects in the topology. If the method succeeds, the full topology is returned in the ppOutputTopo parameter.

You can use the pCurrentTopo parameter to provide a full topology that was previously loaded. If this topology contains objects that are needed in the new topology, the topology loader can re-use them without creating them again. This caching can potentially make the process faster. The objects from pCurrentTopo will not be reconfigured, so you can specify a topology that is actively streaming data. For example, while a topology is still running, you can pre-load the next topology.

Before calling this method, you must ensure that the output nodes in the partial topology have valid IMFStreamSink pointers, not IMFActivate pointers. The Media Session automatically performs this action inside the IMFMediaSession::SetTopology method. However, if you call Load before calling SetTopology, you must bind the output nodes manually. For more information, see Binding Output Nodes to Media Sinks.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Target Platform	Windows
Header	mfidl.h
Library	Mfuuid.lib