Media Video (WMV) is a generic name for the set
of video codec technologies developed by Microsoft. It
is part of the Windows Media framework. The codecs were
originally developed as proprietary codecs for low-bitrate
streaming applications. However, in 2003 Microsoft drafted
a video codec specification based on its Windows Media
Video version 9 codec and submitted it to SMPTE for standardization.
The standard was officially approved in March 2006 as
SMPTE 421M, thus making the Windows Media Video 9 codec
no longer a proprietary technology. Earlier versions of
the codec (7 and 8) are still considered proprietary as
they fall outside the SMPTE 421M standard.
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
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.
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 codecs.
is generally packed into an Advanced Systems Format (ASF)
container format. It can also be put into AVI or Matroska
containers. 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 Mac OS X.
encapsulated in ASF file format, WMV can support DRM facilities.
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 DVDs in a format Microsoft
has branded as WMV HD. This WMV HD content can be played
back on computers or compatible DVD players.