Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
|
|
|
|
| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | WMV (Windows Media Video) File Format |
|---|---|
| Description | File format based in 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 enduser 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, (Microsoft Advanced Systems Format) |
| Has subtype | WMV_WMV9, (file with specific video codec) |
| Has subtype | WMV_WMV9_PRO, (file with specific video codec) |
| Has subtype | WMV file-format variants defined by other video codecs, not documented at this time. |
| LC experience or existing holdings | None |
|---|---|
| LC preference | For file-based compressed video, bitstreams encoded as MPEG-2 (various profiles, the higher the better) or MP4-FF_2 (MPEG-4, various encodings and profiles, the higher the better) are preferred. For uncompressed or losslessly compressed video, which is generally preferred to lossy compressed, MXF may be preferred as a wrapper; this topic will be developed in a future investigation. |
| Disclosure | 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. |
|---|---|
| Documentation | For wrapper documentation, see ASF. See also citations in Useful references below. |
| Adoption | Not known to the compilers of this document. In 2004, AtomFilms began using Windows Media High-Definition Video at 720p resolution for their high definition service that employs. |
| Licensing and patents | See ASF. |
| Transparency | 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 |
| 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 |
| Sound | |
| 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.] |
| 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. |
| General | According to the Web page "Working With Your Video Clips in Windows Movie Maker 2(consulted May 7, 2010), Microsoft moving image programs are created as projects using software like Windows Movie Maker. |
|---|---|
| History |
|
|