Windows Media Video (WMV) is a series of

video codec A video codec is software or Computer hardware, hardware that data compression, compresses and Uncompressed video, decompresses digital video. In the context of video compression, ''codec'' is a portmanteau of ''encoder'' and ''decoder'', while ...

s and their corresponding

video coding format A video coding format (or sometimes video compression format) is a content representation format of digital video content, such as in a data file or bitstream. It typically uses a standardized video compression algorithm, most commonly based on ...

s developed by

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

. It is part of the Windows Media framework. WMV consists of three distinct codecs: the original video compression technology, known as ''WMV'', originally designed for Internet streaming applications as a competitor to

RealVideo RealVideo, also spelled as Real Video, is a suite of proprietary format, proprietary video compression formats developed by RealNetworks — the specific format changes with the version. It was first released in 1997 and was at version 15. RealV ...

, and ''WMV Screen'' and ''WMV Image'' compression technologies, which cater to specialized content. After standardization by the

Society of Motion Picture and Television Engineers The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded by Charles Francis Jenkins in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, technologists, and e ...

(SMPTE), WMV version 9 was adapted for physical-delivery formats such as and

Blu-ray Disc Blu-ray (Blu-ray Disc or BD) is a Digital media, digital optical disc data storage format designed to supersede the DVD format. It was invented and developed in 2005 and released worldwide on June 20, 2006, capable of storing several hours of ...

and became known as . Microsoft also developed a digital container format called Advanced Systems Format to store video encoded by Windows Media Video.

History

In 2003, Microsoft drafted a video compression specification based 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 as

VC-1 SMPTE 421, informally known as VC-1, is a video coding format. Most of it was initially developed as Microsoft's proprietary video format Windows Media Video 9 in 2003. With some enhancements including the development of a new Advanced Profile, ...

, thus making the WMV 9 format an open standard. VC-1 became one of the three video formats for the

Blu-ray Blu-ray (Blu-ray Disc or BD) is a digital optical disc data storage format designed to supersede the DVD format. It was invented and developed in 2005 and released worldwide on June 20, 2006, capable of storing several hours of high-defin ...

video disc, along with H.262/MPEG-2 Part 2 and H.264/MPEG-4 AVC.

Container format

A ''WMV file'' uses the Advanced Systems Format (ASF) container format to 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

file extension File or filing may refer to: Mechanical tools and processes * File (tool), a tool used to remove fine amounts of material from a workpiece. ** Filing (metalworking), a material removal process in manufacturing ** Nail file, a tool used to gen ...

and not the file extension. The ASF container can optionally support

digital rights management Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures, such as access control technologies, can restrict the use of proprietary hardware and copyrighted works. DRM ...

using a combination of

elliptic curve cryptography Elliptic-curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys to provide equivalent security, compared to cryptosystems based on modula ...

key exchange, DES block cipher, a custom block cipher, RC4 stream cipher and the

SHA-1 In cryptography, SHA-1 (Secure Hash Algorithm 1) is a hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest – typically rendered as 40 hexadecimal digits. It was designed by the United States ...

hashing function. Although WMV is generally packed into the ASF container format, it can also be put into the

Matroska Matroska (styled Matroška) is a project to create a container format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. The Matroska Multimedia Container is similar in concept to other containers like ...

container format (with file extension ), or AVI container format (extension ). One common way to store WMV in an AVI file is to use the WMV 9 Video Compression Manager (VCM) codec implementation.

Video compression formats

Windows Media Video

Windows Media Video (WMV) is the most recognized video compression format within the WMV family. Usage of the term ''WMV'' often refers to the Microsoft Windows Media Video format only. Its main competitors are MPEG-4 AVC, AVS,

, and MPEG-4 ASP. The first version of the format, WMV 7, was introduced in 1999, and was built upon Microsoft's implementation of

MPEG-4 Part 2 MPEG-4 Part 2, MPEG-4 Visual (formally International Organization for Standardization, ISO/International Electrotechnical Commission, IEC 14496-2) is a video encoding specification designed by the Moving Picture Experts Group (MPEG). It belongs to ...

. Continued proprietary development led to newer versions of the format, but the

bit stream A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may ...

syntax was not frozen until WMV 9. While all versions of WMV support

variable bit rate Variable bitrate (VBR) is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows ...

, average bit rate, and constant bit rate, WMV 9 introduced several important features including native support for

interlaced video Interlaced video (also known as interlaced scan) is a technique for doubling the perceived frame rate of a video display without consuming extra Bandwidth (signal processing), bandwidth. The interlaced signal contains two field (video), fields ...

, non-square

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...

s, and frame interpolation. WMV 9 also introduced a new profile titled ''Windows Media Video 9 Professional'', 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. It is targeted towards high-definition video content, at resolutions such as

720p 720p (720 lines progressive) is a progressive HD signal format with 720 horizontal lines/1280 columns and an aspect ratio (AR) of 16:9, normally known as widescreen HD (1.78:1). All major HD broadcasting standards (such as SMPTE 292M) includ ...

and

1080p 1080p (1920 × 1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the sc ...

. The ''Simple'' and ''Main'' profile levels in WMV 9 are compliant with the same profile levels in the

specification. The ''Advanced Profile'' in VC-1 is implemented in a new WMV format called ''Windows Media Video 9 Advanced Profile''. It improves compression efficiency for interlaced content and is made transport-independent, making it able to be encapsulated in an

MPEG transport stream MPEG transport stream (MPEG-TS, MTS) or simply transport stream (TS) is a standard digital container format for transmission and storage of audio, video, and Program and System Information Protocol (PSIP) data. It is used in broadcast syst ...

or RTP packet format. The format is not compatible with previous WMV 9 formats, however. WMV is a mandatory video format for PlaysForSure-certified online stores and devices, as well as Portable Media Center devices. The Microsoft Zune,

Xbox 360 The Xbox 360 is a home video game console developed by Microsoft. As the successor to the Xbox (console), original Xbox, it is the second console in the Xbox#Consoles, Xbox series. It was officially unveiled on MTV on May 12, 2005, with detail ...

Windows Mobile Windows Mobile is a discontinued mobile operating system developed by Microsoft for smartphones and personal digital assistants (PDA). Designed to be the portable equivalent of the Windows desktop OS in the emerging Mobile device, mobile/port ...

-powered devices with Windows Media Player, as well as many uncertified devices, support the format. WMV HD mandates the use of WMV 9 for its certification program, at quality levels specified by Microsoft. WMV used to be the only supported video format for the Microsoft Silverlight platform, but the H.264 format is now also supported starting with version 3.

Windows Media Video Screen

Windows Media Video Screen (WMV Screen) are video formats that specialise in screencast content. 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 color palette. 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. Additionally there is MSA1 (aka “MS ATC Screen codec” or “MSS3”) which is used in Live Meeting 2007. FourCCs for the formats are MSS1, MSS2 and MSA1.

Windows Media Video Image

Windows Media Video Image (WMV Image) is a video slideshow format. The format works by applying timing, panning and transition effects to a series of images during playback. 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. 30 frames per second at 1024 px × 768 px resolution) requires heavy computer processing. The latest version of the format, WMV 9.1 Image, used by Photo Story 3, features additional transformation effects, but is not compatible with the original WMV 9 Image format. Hardware support for WMV Image is available from Portable Media Centers,

-powered devices with Windows Media Player 10 Mobile. 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 to

MPEG-2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods ...

before burning a DVD (average file sizes in MPEG-2 are 5 to 6 times the .wmv file).

Versions

Audio compression formats

The audio format used in conjunction with Windows Media Video is typically some version of Windows Media Audio, or in rarer cases, the deprecated Sipro ACELP.net audio format. Microsoft recommends that ASF files containing non-Windows Media formats use the generic file extension.

Players

Software that can play WMV files includes

Windows Media Player Windows Media Player (WMP, officially referred to as Windows Media Player Legacy to retronym, distinguish it from Windows Media Player (2022), the new Windows Media Player introduced with Windows 11) is the first media player (application soft ...

RealPlayer RealPlayer, formerly RealAudio Player, RealOne Player and RealPlayer G2, is a cross-platform media player (software), media player app, developed by RealNetworks. The media player is compatible with numerous container file formats of the multimed ...

MPlayer MPlayer is a free and open-source media player software application. It is available for Linux, OS X and Microsoft Windows. Versions for OS/2, Syllable Desktop, Syllable, AmigaOS, MorphOS and AROS Research Operating System are also available. A ...

, Media Player Classic,

VLC Media Player VLC media player (previously the VideoLAN Client) is a free and open-source software, free and open-source, software portability, portable, cross-platform media player software and streaming media Server (computing), server developed by the Vide ...

and K-Multimedia Player. The Microsoft Zune media management software supports the WMV format, but uses a Zune-specific variation of Windows Media DRM which is used by PlaysForSure. Many third-party players exist for various platforms such as

Linux Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, pac ...

that use the

FFmpeg FFmpeg is a free and open-source software project consisting of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. At its core is the command-line ffmpeg tool itself, designed for processing vide ...

implementation of the WMV format. On the

Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

platform, Microsoft released a

PowerPC PowerPC (with the backronym Performance Optimization With Enhanced RISC – Performance Computing, sometimes abbreviated as PPC) is a reduced instruction set computer (RISC) instruction set architecture (ISA) created by the 1991 Apple Inc., App ...

version of Windows Media Player for

Mac OS X macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

in 2003, but further development of the software ceased. From January 2006 to May 2014, Microsoft endorsed and distributed the 3rd party Flip4Mac, a QuickTime Component developed by Telestream that allowed Macintosh users to play WMV files in any player that used the QuickTime framework. Telestream ended sales of Flip4Mac on 1 July 2019 and officially ended support on 28 June 2020. The Elmedia player, which can play WMV files on Macintosh computers, is still available.

Encoders

Many programs can export video in WMV format; a few examples are

Windows Movie Maker Windows Movie Maker (known as Windows Live Movie Maker for the 2009 and 2011 releases) is a discontinued video editing software program by Microsoft. It was first included in Windows Me on September 14, 2000, and in Windows XP on October 25, 200 ...

Windows Media Encoder Windows Media Encoder (WME) is a discontinued, freeware Multimedia, media codec, encoder developed by Microsoft which enables content developers to convert or capture both live and prerecorded audio, video, and computer screen images to Windows Me ...

, Microsoft Expression Encoder, Sorenson Squeeze, Vegas Pro, AVS Video Editor, VSDC Free Video Editor, Telestream Episode, Telestream FlipFactory, and

. Programs that encode using the WMV Image format include

, AVS Video Editor, and Photo Story.

Digital rights management

While none of the WMV formats themselves contain any

facilities, 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 by CinemaNow. Windows Media DRM, a component of PlaysForSure and Windows Media Connect, is supported on many modern portable video devices and streaming media clients such as the Xbox 360.

Criticism

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. In 2007, the loss of the ability to restore licenses for WMV files in the Windows Media Player 11 was not positively received.

References

External links

Description of the algorithm used for Windows Media encryption

Demonstration of WMV 9 delivering 720p video at 1.8 Mbit/s ABR

Demonstration of WMV 9 delivering 1080p video at 10 Mbit/s ABRHistory of Windows Media Player
(archived 2009) {{Compression Software Implementations Video codecs Microsoft proprietary codecs Microsoft Windows multimedia technology Digital rights management systems