Advanced Systems Format is a proprietary container format from Microsoft for storing digital audio and video files.

If the Advanced System Format acts as a container for video files, the extension is .wmv. If it acts as a container for audio formats the extension is .wma. The format itself does not specify how the file to be saved is to be encoded, but only its structure. ASF files can also store metadata such as artist, album, director, etc.

It is also possible to implement digital rights management (DRM).

The license terms are downloadable from Microsoft and the format can be implemented under a license from Microsoft. However, this is not compatible with any open source license.


- compatible with almost all Windows programs (e.g. PowerPoint)

- tiny size


- proprietary format