Windows Media Metafiles

[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 It has been superseded by MediaPlayer.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.]

This reference documents Windows Media metafiles, which use the .wax, .wvx, .wmx, and .asx file name extensions. It contains overview and programming guide sections, and a full reference section on metafile element tags, their attributes and values, and special conditions related to each element.

A metafile is a file that contains information about other files. A metafile can be used to list a group of media content files that are to be played in order. Windows Media metafile playlists, simply referred to as playlists in this reference document, are one of the most powerful features of Microsoft Windows Media Technologies. Playlists allow you to control and customize your media content. For instance, with playlists you can schedule content to play in succession or insert advertising or special interest clips into a presentation. A further advantage of playlists is that instead of playing a stream, stopping, starting the next stream, and then waiting for it to finish buffering, Windows Media Services and Windows Media Player work together to play the clips one after the other with minimal buffering time or interruption between them.

Windows Media Technologies and other Internet products provide you with the tools to understand user demographics and dynamically customize a broadcast or message for individual users.

This reference is divided into the following sections.

Section Description
About Windows Media Metafiles Introduces Windows Media metafile elements and discusses their purpose.
Windows Media Metafile Guide Details the steps necessary for creating metafiles. Examples illustrate how to use element tags for specific tasks.
Windows Media Metafile Reference Explains in detail each of the metafile elements, their attributes and values, and special conditions related to each. Explains metafile file name extensions and their proper use.


Windows Media Player SDK