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Enumerating Licenses in the Local License Store

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[The feature associated with this page, Windows Media Format 11 SDK, is a legacy feature. It has been superseded by Source Reader and Sink Writer. Source Reader and Sink Writer have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Source Reader and Sink Writer instead of Windows Media Format 11 SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

Enumeration is a process of getting information about the licenses in the local license store, by stepping through them one by one. You can create a license enumeration by calling the IWMDRMLicenseManagement::CreateLicenseEnumeration.

The most common reason for enumerating through licenses in the store is to find a particular license for decryption of some content.

The IWMDRMLicense interface serves as both a portal to the individual license results and as the enumerator. When the license enumeration is created, the first license in the list is loaded into the IWMDRMLicense interface. Most of the methods of IWMDRMLicense enable you to get information about the license or to create objects to encrypt or decrypt content based on the license. However, there are two methods that control the enumeration: GetNext and ResetEnumeration. GetNext loads the next license in the list into the interface. ResetEnumeration returns the enumeration to the state it was in when it was first created. When the enumeration is reset, the first license in the list is loaded back into the IWMDRMLicense interface.

When you have reached the last license in the list, the next call to GetNext returns ERROR_NO_MORE_ITEMS.

If your application performs an action with the content that is covered by DRM, you should check the licenses in the local license store for the rights and for other limiting factors, such as output protection levels (OPLs).

Getting Information from Licenses in the Local License Store