IMFAttributes::GetUnknown Method

Retrieves an interface pointer associated with a key.

Syntax

public:
HRESULT GetUnknown(
         REFGUID guidKey,
         REFIID riid,
         LPVOID *ppv
)

Parameters

guidKey
Type: REFGUID 

[in]

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

riid
Type: REFIID 

[in]

Interface identifier (IID) of the interface to retrieve.

ppv
Type: LPVOID *

[out, optional]

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

Return value

Type: HRESULT 

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

Return codes
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.

Refer to Media Foundation return codes.

Remarks

Requirements

Header: Declared in mfobjects.h (include mfidl.h).

Library: Use Mfuuid.lib.