IMFAttributes::GetUnknown method (mfobjects.h)

Retrieves an interface pointer associated with a key.

Syntax

HRESULT GetUnknown(
  [in]  REFGUID guidKey,
  [in]  REFIID  riid,
  [out] LPVOID  *ppv
);

[in] guidKey

GUID that identifies which value to retrieve. The attribute type must be MF_ATTRIBUTE_IUNKNOWN.

[in] riid

Interface identifier (IID) of the interface to retrieve.

[out] ppv

Receives a pointer to the requested interface. The caller must release the interface.

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.
E_NOINTERFACE	The attribute value is an IUnknown pointer but does not support requested interface.
MF_E_ATTRIBUTENOTFOUND	The specified key was not found.
MF_E_INVALIDTYPE	The attribute value is not an IUnknown pointer.

This interface is available on the following platforms if the Windows Media Format 11 SDK redistributable components are installed:

Windows XP with Service Pack 2 (SP2) and later.
Windows XP Media Center Edition 2005 with KB900325 (Windows XP Media Center Edition 2005) and KB925766 (October 2006 Update Rollup for Windows XP Media Center Edition) installed.

Requirement	Value
Minimum supported client	Windows Vista [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2008 [desktop apps \| UWP apps]
Target Platform	Windows
Header	mfobjects.h (include Mfidl.h)
Library	Mfuuid.lib