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Article ID: 284094 - Last Review: November 17, 2003 - Revision: 2.2

This article was previously published under Q284094


The only difference between ASF files and WMV or WMA files are the file extensions and the MIME types. The MIME type for a WMV file is video/x-ms-wmv, and for WMA it is audio/x-ms-wma. The MIME type for ASF is video/x-ms-asf. The basic internal structure of the files is identical.


The change in extensions was made to make it easier for an application to identify the content of a media file. A .wma file extension designates a file containing only audio. A .wmv extension designates a file containing both video and audio.

  • Microsoft Windows Media Services 4.1
  • Microsoft Windows Media Encoder 7.0
  • Microsoft Windows Media Encoder 7.1
kbinfo KB284094
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