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WMV is not built solely on Microsoft in-house technology. It is believed that WMV version 7 (WMV1) was built upon Microsoft's own non-standard version of MPEG-4 Part 2 . However, as WMV version 9 has been standardized as an independent SMPTE standard (421M, also known as VC-1 ), it's reasonable to believe that WMV has sufficiently evolved in a different direction than MPEG-4 to be considered a unique codec in its own right. There are currently (April 2006) 16 companies in the VC-1 patent pool. Microsoft is also one of the members of the MPEG-4 AVC/H.264 patent pool.

The video stream is often combined with an audio stream of Windows Media Audio and encapsulated in Advanced Systems Format files, carrying the .wmv or .asf file extensions.

WMV files are played by players such as MPlayer or Windows Media Player , the latter being only available for Microsoft Windows and Macintosh systems. Many third-party players exist for various platforms such as Linux that use the FFmpeg implementation of the WMV Codec s.

WMV is generally packed into an Advanced Systems Format (ASF) container. It can also be put into AVI or Matroska container formats. The resulting files may be named .avi if it is an AVI-contained file, or .wmv or .asf if it is an ASF file, or .mkv if it is an MKV file. WMV can be stored in an AVI file when encoding with the VirtualDub encoder and using the WMV9 VCM codec implementation. Microsoft's Windows Media Player for the Mac does not support all WMV encoded files since it supports only the ASF file container. More files can be played with Flip4Mac and Quicktime or MPlayer for MacOSX.

When encapsulated in ASF file format, WMV can support Digital Rights Management facilities intended to protect Intellectual Property rights.

Besides being one of the most popular codecs for distributing video on the Internet, the codec is also used to distribute high definition video on standard DVD s in a format Microsoft has branded as WMV HD . This WMV HD content can be played back on computers or compatible DVD players.


CODECS

  • Windows Media Video v7 ( FourCC : WMV1)

  • Windows Media Video v7 Screen (FourCC: MSS1) - Optimized for low-bitrate screen captures

  • Windows Media Video v8 (FourCC: WMV2)

  • Windows Media Video 9 Screen (FourCC: MSS2) - Optimized for low-bitrate screen captures

  • Windows Media Video 9 Image (FourCC: WMVP) - Used in Microsoft Photo Story 1 and 2 products

  • Windows Media Video 9 Image v2 (FourCC: WVP2) - Used in Microsoft Photo Story 3 and newer products

  • Windows Media Video 9 (FourCC: WMV3) - Compliant with VC-1 Simple and Main Profile specifications

  • Windows Media Video 9 Advanced Profile (FourCC: WMVA) - Early AP implementation. VC-1 non-compliant. Deprecated.

  • Windows Media Video 9 Advanced Profile (FourCC: WVC1) - Compliant with VC-1 Advanced Profile specification.



SEE ALSO

  • VC-1 - The SMPTE codec standard based on WMV9 but expanded to support video and broadcast industry requirements.

  • MPlayer - A third-party open source cross-platform media player capable of playing many WMV files using FFmpeg.

  • FFmpeg - A third-party cross-platform free software codec library which aims to implement WMV and VC-1 among other formats.

  • Windows Media Audio - The audio codec counterpart.

  • WMV Player - A third-party commercial codec which allows viewing of WMV files in QuickTime for Mac OS X .

  • Flip4Mac - Quicktime component to play Windows Media files in Quicktime ( Mac OS X )

  • Windows Movie Maker - A video editing tool included with Windows XP .

  • Windows Media DRM - A Digital Rights Management component of Windows Media technologies commonly associated with the WMV format that restricts the rights that the user has on the content.



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