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Windows Media 9 Audio Codec
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Format Description Properties
• ID: fdd000092
• Short name: WMA9
• Content categories: sound
• Format category: bitstream encoding
• Last significant update: 2004-05-13
Identification and description 
| Full name | Windows Media 9 Audio Codec |
| Description | Audio bitstream produced by the Windows Media 9 audio codec. |
| Production phase | Generally used in files that represent a final-state format for end-user delivery. |
| Relationship to other formats | |
| Used by | WMA_WMA9, Windows Media Audio file with WMA9 codec |
Local use
| LC experience or existing holdings | |
| LC preference | See WMA |
Sustainability factors
| Disclosure | Proprietary. Developed by Microsoft. |
| Documentation | Specifications not disseminated. Some descriptions and software development kits available from Microsoft. |
| Adoption | Not known to the compilers of this document; the WMA file format is widely adopted. |
| Licensing and patent claims | See ASF for link to pages covering licensing of Windows Media and the Advanced Systems Format. |
| Transparency | Depends upon algorithms and tools to read; will require sophistication to build tools. |
| Self-documentation | Not applicable |
| External dependencies | None |
| Technical protection considerations | Not applicable |
Quality and functionality factors (video)
| Normal rendering | Good support. |
| Fidelity (support for high audio resolution) | From the codecs page at the Microsoft Windows Media web site: "For use in most scenarios. This codec . . . supports VBR [variable bit rate] audio that enables even higher quality audio at smaller file sizes. Windows Media Audio 9 is backward-compatible with previous Windows Media Audio-compatible decoders." The site indicates that higher quality is provided by WMA9_PRO. |
| Support for multiple sound channels | None |
| Functionality beyond normal rendering | Not applicable |
File type signifiers
| Tag type | Value | Note |
| Filename Extension | Not applicable | |
| Internet Media Type | Not applicable | |
| Magic numbers | Not applicable | |
Notes
Format specifications
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Useful references
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WMA
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Last Updated: Wednesday, 07-Mar-2007 12:40:20 EST
