Sustainability of Digital Formats: Planning for Library of Congress Collections

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WMV (Windows Media Video) File Format

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name WMV (Windows Media Video) File Format
Description File format based on ASF (Advanced Systems Format) that wraps a video bitstream. This web site documents versions of the format that contain bitstreams encoded by Windows Media Video 9, which is also known as VC-9. Some WMV files may also employ Windows Media Video 7 and 8 codecs.
Production phase Often final state format for end user delivery; sometimes a middle-state format, e.g., a high-quality video representation for archiving or as a source when producing lower-resolution streaming versions.
Relationship to other formats
    Subtype of ASF, Advanced Systems Format. From Microsoft.
    Has subtype WMV_WMV9, Windows Media Video File with WMV9 Codec
    Has subtype WMV_WMV9_PRO, Windows Media Video File with WMV9 Professional Codec
    Has subtype WMV file-format variants defined by other video codecs, not documented at this time.

Local use Explanation of format description terms

LC experience or existing holdings The Library of Congress has a small amount of Windows Media Video files in its collections.
LC preference

See the Library of Congress Recommended Formats Statement for format preferences for file-based video.

Sustainability factors Explanation of format description terms


Microsoft's proprietary ASF wrapper format is fully documented. For information about the disclosure of information about the bitstreams wrapped by WMV, see the descriptions of individual codecs listed under Relationships, above.


For wrapper documentation, see ASF. See also citations in Useful references below.


Supported for playback in Microsoft products such as Windows Media Center and Windows Media Player. For Windows Movie Maker in Windows XP (link available through Internet Archive), it is one of two output formats for video. In 2004, AtomFilms (which became and later CC:Studios) announced the use of Windows Media High-Definition Video at 720p resolution for their high definition service. Comments welcome.

    Licensing and patents See ASF.

File format is transparent. See information on versions that incorporate different codecs: WMV_WMV9 and WMV_WMV9_PRO.

Self-documentation See ASF
External dependencies None
Technical protection considerations See ASF

Quality and functionality factors Explanation of format description terms

Moving Image
Normal rendering Good support.
Clarity (high image resolution) Depends upon encoding; see WMV9 or WMV9_PRO
Functionality beyond normal rendering Support for various elements offered by ASF
Fidelity (high audio resolution) Moderate to excellent; outcome will depend on codec selected and upon the type and level of compression.
Multiple channels Depends upon encoding; see WMA9_PRO
Support for user-defined sounds, samples, and patches [Not investigated at this writing.]

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension wmv
Internet Media Type video/x-ms-wmv
From The File Extension Source. No examples found in IANA MIME Media Types or in LC implementation of Apache mime.types.
Magic numbers Hex: 30 26 B2 75 8E 66 CF 11 A6 D9 00 AA 00 62 CE 6C
ASCII: 0&²u.fÏ.¦Ù.ª.bÎl
For extension asf (see ASF), from Gary Kessler's File Signatures Table.
ASF GUID BC19EFC0-5B4D-11CF-A8FD-00805F5C442B
Globally Unique IDentifier for ASF_Video_Media; from Advanced Systems Format (ASF) Specification.
Pronom PUID fmt/133
Wikidata Title ID Q280761

Notes Explanation of format description terms


Format specifications Explanation of format description terms

Useful references


Last Updated: 05/01/2023