Metafile Extension Guidelines
[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 It has been superseded by MediaPlayer.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.]
A file name extension provides an independent software vendor (ISV) with information about the rendering requirements of an application that uses the extension, and enables content authors to target general types of players.
Windows Media metafile name extensions are used to identify the format of the Windows Media files that a metafile references. Windows Media metafiles with .wax, .wvx, or .asx extensions reference files with .wma, .wmv, and .asf extensions, respectively. All metafiles, regardless of the file name extension used, have the ASX element tag at the beginning of the file with the version attribute specified.
The following table shows the media file types referenced by each type of metafile file name extension. The columns list media file name extensions, the rows list metafile name extensions. An X in a column indicates a media file type that can be referenced by a particular metafile file name extension.
| Extension | .asf | .wma | .wmv |
|---|---|---|---|
| .wvx | X | X | X |
| .wax | X | X | |
| .asx | X |
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