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ConvertPluginCLSID Subkey

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 It has been superseded by MediaPlayer.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

When Windows Media Player 11 encounters a custom file name extension, it looks for a registry subkey that matches the extension. The subkey is described in File Name Extension Registry Settings. In some cases, the extension's subkey has a subkey named ConvertPluginCLSID.

For example, suppose you have created a custom file format (with file name extension .xyz) and a conversion plug-in that converts the files to a format supported by Windows Media Player Then you would store the class ID of the plug-in in one or both of the following subkeys.

HKEY_LOCAL_MACHINE\Software\Microsoft\Multimedia\WMPlayer\Extensions\.xyz\ConvertPluginCLSID

HKEY_CURRENT_USER\Software\Microsoft\MediaPlayer\Player\Extensions\.xyz\ConvertPluginCLSID

The ConvertPluginCLSID subkey specifies the class IDs of plug-ins that Windows Media Player can use to convert a media file from its custom format to a format supported by the Player.

The ConvertPluginCLSID subkey has the following entries.

  • A default entry that represents the default conversion plug-in.
  • A named entry that represents the default conversion plug-in.
  • Additional named entries that represent alternate conversion plug-ins.

For example, suppose a custom file format has a default conversion plug-in and two alternate conversion plug-ins. The registry entries under the ConvertPluginCLSID subkey would have the following form.

Name Type Value
Default REG_SZ The class ID, in registry format, of the default conversion plug-in.
The class ID, in registry format, of the default conversion plug-in. REG_SZ The friendly name of the default conversion plug-in.
The class ID, in registry format, of the first alternate conversion plug-in. REG_SZ The friendly name of the first alternate conversion plug-in.
The class ID, in registry format, of the second alternate conversion plug-in. REG_SZ The friendly name of the second alternate conversion plug-in.

 

Note that the default conversion plug-in is represented by two registry entries: the default entry and a named entry. Windows Media Player uses the default entry to determine which plug-in is the default (primary) conversion plug-in. Windows Media Player uses the named entries to obtain friendly names for all conversion plug-ins, including the default plug-in.

The friendly name of a conversion plug-in is determined by the company that creates the plug-in. Windows Media Player might display the friendly name in its user interface.

When Windows Media Player attempts to convert a file from a custom format to a standard format, it first loads the default plug-in. If the default plug-in fails to convert the file and returns NS_E_WMP_CONVERT_PLUGIN_UNKNOWN_FILE_OWNER, the Player loads each alternate plug-in until a successful conversion happens or there are no more plug-ins to try. The Player does not display a warning message if no conversion plug-in is found for the file name extension.

The ConvertPluginCLSID registry entry is supported by Windows Media Player 11.

File Name Extension Registry Settings

Windows Media Player Conversion Plug-ins