Windows Media Technology: FAQ

This is a FAQ page for Windows Media Technology.

Q.: What is the difference between .WMV and .ASF?

A.: From MSDN:

"A file name extension provides an independent software vendor with information about the rendering requirements of an application that uses that particular extension.

The file name extension you must use for a file created by an application based on the Windows Media Format SDK is determined by the type of content in the file. Use the following logic to determine the file name extension you must use.

If the file contains any streams encoded with third-party codecs or any unsupported uncompressed data (including arbitrary data), the file must use the .asf extension.

If the file contains no unsupported streams and contains one or more video streams either uncompressed or encoded with any Windows Media video codec, the file must use the .wmv extension. These files may also include PCM audio streams, audio streams encoded with any Windows Media audio codec, script streams, and Web streams.

If the file contains no unsupported streams and no supported video streams, and contains one or more audio streams either uncompressed PCM or encoded with any Windows Media audio codec, the file must use the .wma extension. These files may also contain script streams, and Web streams.

If the file contains only streams that are neither audio nor video, it must use the .asf extension."