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Windows Media Video

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"WMV" redirects here. For the container file format.wmv, seeAdvanced Systems Format.

Windows Media Video(WMV) is a series ofvideo codecsand their correspondingvideo coding formatsdeveloped byMicrosoft.It is part of theWindows Mediaframework. WMV consists of three distinct codecs: The original video compression technology known asWMV,was originally designed for Internet streaming applications, as a competitor toRealVideo.The other compression technologies,WMV ScreenandWMV Image,cater for specialized content. After standardization by theSociety of Motion Picture and Television Engineers(SMPTE),[1][2]WMV version 9 was adapted for physical-delivery formats such asHD DVDandBlu-ray Discand became known asVC-1.[3][4]Microsoft also developed adigital container formatcalledAdvanced Systems Formatto store video encoded by Windows Media Video.

History

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In 2003, Microsoft drafted avideo compression specificationbased on its WMV 9 format and submitted it to SMPTE for standardization. The standard was officially approved in March 2006 as SMPTE 421M, better known asVC-1,thus making the WMV 9 format an open standard. VC-1 became one of the three video formats for theBlu-rayvideo disc, along withH.262/MPEG-2 Part 2andH.264/MPEG-4 AVC.[3][4]

Container format

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Main article:Advanced Systems Format
A screenshot fromVLC Media Playerof what a WMV file may contain.

AWMV fileuses theAdvanced Systems Format(ASF)container formatto encapsulate the encoded multimedia content. While the ASF can encapsulate multimedia in other encodings than those the WMV file standard specifies, those ASF files should use the.asffile extensionand not the.wmvfile extension.[5][failed verification]

The ASF container can optionally supportdigital rights managementusing a combination ofelliptic curve cryptographykey exchange,DESblock cipher, a custom block cipher,RC4stream cipher and theSHA-1hashing function.

Although WMV is generally packed into the ASF container format, it can also be put into theMatroska[6]container format (with file extension.mkv), orAVIcontainer format (extension.avi). One common way to store WMV in an AVI file is to use the WMV 9Video Compression Manager (VCM)codec implementation.[7][8]

Video compression formats

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Windows Media Video

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Diagram illustrating the relative frame sizes of several common video resolutions targeted by Windows Media Video 9 Professional, starting with480p

Windows Media Video (WMV) is the most recognizedvideo compression formatwithin the WMV family. Usage of the termWMVoften refers to the Microsoft Windows Media Video format only. Its main competitors areMPEG-4 AVC,AVS,RealVideo,andMPEG-4 ASP.The first version of the format, WMV 7, was introduced in 1999, and was built upon Microsoft's implementation ofMPEG-4 Part 2.[9]Continued proprietary development led to newer versions of the format, but thebit streamsyntax was not frozen until WMV 9.[10]While all versions of WMV supportvariable bit rate,average bit rate,andconstant bit rate,WMV 9 introduced several important features including native support forinterlaced video,non-squarepixels,andframe interpolation.[11]WMV 9 also introduced a new profile titledWindows Media Video 9 Professional,[12]which is activated automatically whenever the video resolution exceeds 300,000 pixels (e.g., 528 px × 576 px, 640 px × 480 px or 768 px × 432 px and beyond) and the bitrate 1 Mbit/s[citation needed].It is targeted towards high-definition video content, at resolutions such as720pand1080p.

TheSimpleandMainprofile levels in WMV 9 are compliant with the same profile levels in theVC-1specification.[13]TheAdvanced Profilein VC-1 is implemented in a new WMV format calledWindows Media Video 9 Advanced Profile.It improves compression efficiency for interlaced content and is made transport-independent, making it able to be encapsulated in anMPEG transport streamorRTPpacket format. The format is not compatible with previous WMV 9 formats, however.[14]

WMV is a mandatory video format forPlaysForSure-certified online stores and devices, as well asPortable Media Centerdevices. TheMicrosoft Zune,Xbox 360,Windows Mobile-powered devices with Windows Media Player, as well as many uncertified devices, support the format.[15]WMV HDmandates the use of WMV 9 for its certification program, at quality levels specified by Microsoft.[16]WMV used to be the only supported video format for theMicrosoft Silverlightplatform, but the H.264 format is now also supported starting with version 3.[17]

Windows Media Video Screen

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Windows Media Video Screen (WMV Screen) are video formats that specialise inscreencastcontent. They can capture live screen content, or convert video from third-party screen-capture programs into WMV 9 Screen files. They work best when the source material is mainly static and contains a small colorpalette.[18]

One of the uses for the format is computer step-by-step demonstration videos. The first version of the format was WMV 7 Screen. The second version, WMV 9 Screen, supports VBR encoding in addition to CBR.[18]Additionally there is MSA1 (aka “MS ATC Screen codec” or “MSS3” ) which is used inLive Meeting2007.FourCCsfor the formats areMSS1,MSS2andMSA1.[19]

Windows Media Video Image

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Windows Media Video Image (WMV Image) is a videoslideshowformat. The format works by applying timing,panningand transition effects to a series of images during playback.[20]The codec achieves a higher compression ratio and image quality than WMV 9 for still images as files encoded with WMV Image store static images rather than full-motion video.

Since the format relies on the decoder (player) to generate video frames in real-time, playing WMV Image files even at moderate resolutions (e.g. 30frames per secondat 1024 px × 768 px resolution) requires heavy computer processing. The latest version of the format, WMV 9.1 Image, used byPhoto Story3, features additional transformation effects, but is not compatible with the original WMV 9 Image format.[20]

Hardware support for WMV Image is available from Portable Media Centers,Windows Mobile-powered devices with Windows Media Player 10 Mobile.[15]

Since no known domestic DVD player supports this format, users of Photo Story 3 wishing to generate material capable of being played in a DVD player will first have to convert toMPEG-2before burning a DVD (average file sizes in MPEG-2 are 5 to 6 times the.wmv file).

Versions

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Public Name FourCC Description
Microsoft MPEG-4 version 1 MPG4 Video for Windows-based codec. Non-standard MPEG-4 codec incompatible with the later standardized version ofMPEG-4 Part 2.
Microsoft MPEG-4 version 2 MP42 VfW-based codec. Non-compliant with finalized MPEG-4 part 2 standard.
Microsoft MPEG-4 version 3 MP43 VfW-based codec. Non-compliant with finalized MPEG-4 part 2 standard. Eventually locked for encoding only with ASF files (build 3688 and earlier could also encode to AVI).[21]
Microsoft ISO MPEG-4 version 1 MP4S DirectX Media Objects(DMO)-based codec. MPEG-4Simple Profilecompliant.
Microsoft ISO MPEG-4 version 1.1 M4S2 MPEG-4Advanced Simple Profilecompliant.[22]
Windows Media Video 7 WMV1 DMO-based codec.
Windows Media Screen 7 MSS1 DMO-based codec. Optimized for low-bitrate sequential screen captures or screencasts. Deprecated in favor of Windows Media 9 Screen codec.
Windows Media Video 8 WMV2 DMO-based codec.
Windows Media Video 9 WMV3 DMO-based codec. Video for Windows (VfW/VCM) version also available.[1]
Windows Media Video 9 Screen MSS2 DMO-based codec. Optimized for low-bitrate sequential screen captures or screencasts.
Windows Media Video 9.1 Image WMVP DMO-based codec. Optimized for encoding video from sequential bitmap images. Used, for instance, by Photo Story.
Windows Media Video 9.1 Image V2 WVP2 DMO-based codec. Optimized for encoding video from sequential bitmap images. Used, for instance, by Photo Story.
Windows Media Video 9 Advanced Profile WMVA DMO-based codec. Deprecated as non-VC-1-compliant.
Windows Media Video 9 Advanced Profile WVC1 DMO-based codec. VC-1 compliant format.

Audio compression formats

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The audio format used in conjunction with Windows Media Video is typically some version ofWindows Media Audio,or in rarer cases, the deprecated SiproACELP.netaudio format. Microsoft recommends that ASF files containing non-Windows Media formats use the generic.ASFfile extension.

Players

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Software that can play WMV files includesWindows Media Player,RealPlayer,MPlayer,Media Player Classic,VLC Media PlayerandK-Multimedia Player.The Microsoft Zune media management software supports the WMV format, but uses a Zune-specific variation ofWindows Media DRMwhich is used by PlaysForSure. Many third-party players exist for various platforms such asLinuxthat use theFFmpegimplementation of the WMV format.

On theMacintoshplatform, Microsoft released aPowerPCversion of Windows Media Player forMac OS Xin 2003,[23]but further development of the software ceased. From January 2006 to May 2014, Microsoft endorsed and distributed the 3rd partyFlip4Mac,aQuickTimeComponent developed byTelestreamthat allowed Macintosh users to play WMV files in any player that used the QuickTime framework.[24][25]Telestream ended sales of Flip4Mac on 1 July 2019 and officially ended support on 28 June 2020.[26]The Elmedia player, which can play WMV files on Macintosh computers, is still available.

Encoders

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Many programs can export video in WMV format; a few examples areWindows Movie Maker,Windows Media Encoder,Microsoft Expression Encoder,Sorenson Squeeze,[27]Sony Vegas Pro,[28]AVS Video Editor,VSDC Free Video Editor,Telestream Episode,Telestream FlipFactory,[29][30]andFFmpeg.

Programs that encode using the WMV Image format includeWindows Media Encoder,AVS Video Editor,andPhoto Story.

Digital rights management

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Main article:Windows Media DRM

While none of the WMV formats themselves contain anydigital rights managementfacilities, the ASF container format, in which a WMV stream may be encapsulated, can. Windows Media DRM, which can be used in conjunction with WMV, supports time-limited subscription video services such as those offered byCinemaNow.[31]Windows Media DRM, a component of PlaysForSure andWindows Media Connect,is supported on many modern portable video devices and streaming media clients such as the Xbox 360.

Criticism

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WMV has been the subject of numerous complaints from users and the press. Users dislike the digital rights management system which is sometimes attached to WMV files.[32]In 2007, the loss of the ability to restore licenses for WMV files in the Windows Media Player 11 was not positively received.[32]

See also

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  • JPEG XR/HDHD,an image file format and format developed by Microsoft

References

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  2. ^"Microsoft VC-1 Codec Now a Standard".betanews.3 April 2006.Archivedfrom the original on 24 February 2009.Retrieved3 May2018.
  3. ^ab"Blu-ray Disc BD-ROM Specification Adds Microsoft's VC-1 Advanced Video Codec".microsoft.Archived fromthe originalon 15 June 2007.Retrieved3 May2018.
  4. ^ab"Microsoft Technology Brings HD DVD to the Mainstream".microsoft.Archived fromthe originalon 9 August 2007.Retrieved3 May2018.
  5. ^"The Difference Between ASF and WMV/WMA Files".November 17, 2003. Archived fromthe originalon 2007-08-19.
  6. ^"Archives | Matroska".2003-06-19. Archived fromthe originalon 2011-10-11.Retrieved2011-10-12.As a sidenote, his muxer filter will also allow transmu xing of Microsoft WMV9 video files ( ASF/WMV container ) fine into matroska files, from Graphedit, and with WMV9 VCM installed on your PC you can even open and edit the files in latest VirtualdubMod
  7. ^Microsoft Corporation (2003-07-07)Windows Media Video 9 VCMArchived2009-08-10 at theWayback Machine,Retrieved on 2009-08-07
  8. ^"Windows - Official Site for Microsoft Windows 10 Home & Pro OS, laptops, PCs, tablets & more".microsoft.Archived fromthe originalon 1 November 2017.Retrieved3 May2018.
  9. ^"News, Features, Reviews, Forums and Resources for the Professional Content Creator - Creative Planet Network".Creative Planet Network.Archived fromthe originalon 22 February 2009.Retrieved3 May2018.
  10. ^"Windows Media Audio & Video 9 Series".microsoft.Archived fromthe originalon 28 September 2007.Retrieved3 May2018.
  11. ^"Windows - Official Site for Microsoft Windows 10 Home & Pro OS, laptops, PCs, tablets & more".microsoft.Archived fromthe originalon 21 August 2010.Retrieved3 May2018.
  12. ^"Windows Media 9 Series Beta Reviewer's Guide"(PDF).Archived fromthe original(PDF)on September 28, 2007.
  13. ^"Using the Advanced Settings of the Windows Media Video 9 Advanced Profile Codec".Microsoft.Archived fromthe originalon August 11, 2007.
  14. ^Waggoner, Ben (21 February 2007)."Best Practices for Windows Media Encoding".Streaming Media Magazine.Archivedfrom the original on 26 July 2011.Retrieved3 May2018.
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  20. ^ab"Windows - Official Site for Microsoft Windows 10 Home & Pro OS, laptops, PCs, tablets & more".microsoft.Archived fromthe originalon 1 November 2017.Retrieved3 May2018.
  21. ^VirtualDubVirtualDub documentation: codecsArchived2011-05-16 at theWayback Machine,Retrieved on 2009-11-28
  22. ^MPEG4 Part 2 Video DecoderMSDN documentation: Profiles and LevelsArchived2013-12-03 at theWayback Machine,Retrieved on 2009-11-28
  23. ^"Office 365 for Mac, Office 2016 for Mac".office.Archived fromthe originalon 3 May 2018.Retrieved3 May2018.
  24. ^"Telestream Press Release".telestream.net.Archived fromthe originalon 10 September 2006.Retrieved10 September2006.
  25. ^"Knowledge Article: Flip4Mac Player: Why is Telestream charging for Flip4Mac Player".Archivedfrom the original on 22 August 2021.Retrieved22 August2021.
  26. ^"Knowledge Article: Flip4Mac retired as of July 1, 2019".Archivedfrom the original on 22 August 2021.Retrieved22 August2021.
  27. ^"Sorenson Media - Next Generation Television Starts Here".Sorenson Media.Archived fromthe originalon 23 March 2018.Retrieved3 May2018.
  28. ^"Sony Creative Software - Vegas Pro 8 - Technical Specifications".sonycreativesoftware.Archived fromthe originalon 2 March 2008.Retrieved3 May2018.
  29. ^"Supported file formats in Adobe Premiere Pro 2.0".adobe.Archived fromthe originalon 13 October 2007.Retrieved3 May2018.
  30. ^"EMS - PLAYOUT - CG - MAM - INGEST - ENCODER - IP MULTIVIEWER".easymediasuite.Archivedfrom the original on 30 September 2017.Retrieved3 May2018.
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  32. ^ab"Microsoft Media Player shreds your rights".theinquirer.net.Archived from the original on 7 September 2007.Retrieved3 May2018.{{cite web}}:CS1 maint: unfit URL (link)
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