SMPTE 421, informally known as VC-1, is a

video coding format A video coding format (or sometimes video compression format) is a content representation format for storage or transmission of digital video content (such as in a data file or bitstream). It typically uses a standardized video compression algori ...

. Most of it was initially developed as

Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...

's proprietary video format Windows Media Video 9 in 2003. With some enhancements including the development of a new Advanced Profile, it was officially approved as a

SMPTE The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, technologists, and executives working in the m ...

standard on April 3, 2006. It was primarily marketed as a lower-complexity competitor to the H.264/MPEG-4 AVC standard. After its development, several companies other than Microsoft asserted that they held

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A ...

s that applied to the technology, including

Panasonic formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...

LG Electronics LG Electronics Inc. () is a South Korean multinational electronics company headquartered in Yeouido-dong, Seoul, South Korea. LG Electronics is a part of LG Corporation, the fourth largest '' chaebol'' in South Korea, and often considered a ...

and

Samsung Electronics Samsung Electronics Co., Ltd. (, sometimes shortened to SEC and stylized as SΛMSUNG) is a South Korean multinational electronics corporation headquartered in Yeongtong-gu, Suwon, South Korea. It is the pinnacle of the Samsung chaebol, a ...

. VC-1 is supported in the now-deprecated Microsoft Silverlight, the briefly-offered

HD DVD HD DVD (short for High Definition Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the ...

disc format, and the Blu-ray Disc format.

Format

VC-1 is an evolution of the conventional block-based motion-compensated hybrid video coding design also found in H.261,

MPEG-1 Part 2 MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making ...

, H.262/MPEG-2 Part 2, H.263, and MPEG-4 Part 2. It was widely characterized as an alternative to the

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...

and

MPEG The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and f ...

video codec standard known as H.264/MPEG-4 AVC. The Advanced Profile of VC-1 contains tools designed for coding interlaced video sequences as well as progressive scan video. The main goal of the development and standardization of the VC-1 Advanced Profile was to support interlace-optimized compression of interlaced content without first converting it to progressive scan, making it more attractive to broadcast and video industry professionals using the

1080i 1080i (also known as Full HD or BT.709) is a combination of frame resolution and scan type. 1080i is used in high-definition television (HDTV) and high-definition video. The number "1080" refers to the number of horizontal lines on the scre ...

format. Both

and Blu-ray Disc adopted VC-1 as a supported video format, meaning their video playback devices are required be capable of decoding and playing video-content compressed using VC-1.

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

partially supports HD DVD playback by including the VC-1 decoder and some related components needed for playback of VC-1 encoded HD DVD movies. Microsoft designated VC-1 as the

Xbox 360 The Xbox 360 is a home video game console developed by Microsoft. As the successor to the original Xbox, it is the second console in the Xbox series. It competed with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generati ...

video game console A video game console is an electronic device that outputs a video signal or image to display a video game that can be played with a game controller. These may be home consoles, which are generally placed in a permanent location connected to ...

's official video format, and game developers could use VC-1 for full motion video included with games. By means of an October 31, 2006 update, all formats of Windows Media Video could be played on the Xbox 360 from a disc, USB storage device, or streaming from a PC via Windows Media Connect/Windows Media Player 11. VC-1 is supported in the

PlayStation 3 The PlayStation 3 (PS3) is a home video game console developed by Sony Computer Entertainment. The successor to the PlayStation 2, it is part of the PlayStation brand of consoles. It was first released on November 11, 2006, in Japan, November ...

console and 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 of vid ...

project also includes a VC-1 decoder. On August 24, 2012, the

Raspberry Pi Raspberry Pi () is a series of small single-board computers (SBCs) developed in the United Kingdom by the Raspberry Pi Foundation in association with Broadcom. The Raspberry Pi project originally leaned towards the promotion of teaching basic ...

Foundation announced hardware decoding support for VC-1.

Microsoft codec implementations

The VC-1 codec specification has so far been implemented by Microsoft in the form of three codecs, each identified with a unique four character code.

WMV3

The Simple and Main Profiles of VC-1 remained completely faithful to the existing WMV3 implementation, making WMV3 bitstreams fully VC-1 compliant. The WMV3 codec was designed to primarily support progressive encoding for computer displays. An interlaced encoding mode was implemented, but quickly became deprecated when Microsoft started implementing WMV Advanced Profile. Whereas WMV3 progressive encoding was implemented using the YUV 4:2:0 color sampling scheme, the deprecated interlaced mode was implemented using the less common YUV 4:1:1 sampling scheme. The Windows Media Video 9 (WMV3) codec implements the Simple and Main modes of the VC-1 codec standard, providing high-quality video for streaming and downloading. "It provides support for a wide range of bit rates, from high-definition content at one-half to one-third the bit rate of MPEG-2, to low-bit-rate Internet video delivered over a dial-up modem. This codec also supports professional-quality downloadable video with two-pass and variable bit rate (VBR) encoding." A number of high definition movies and videos have been released commercially in a format dubbed

WMV HD Windows Media High Definition Video (WMV HD) is the marketing name for high definition videos encoded using Microsoft Windows Media Video 9 codecs. These low-complexity codecs make it possible to watch high definition movies in 1280×720 (720p ...

. These titles are encoded with WMV3 Main Profile @ High Level (MP@HL).

WMVA

WMVA was the original implementation of WMV Advanced Profile prior to the acceptance of the VC-1 draft by SMPTE. The codec was distributed with

Windows Media Player Windows Media Player (WMP) is the first media player (application software), media player and media library application that was developed by Microsoft for playing sound reproduction, audio, video and viewing images on personal computers runnin ...

10 and Windows Media Format SDK 9.5 install packages. There are slight bitstream differences between WMVA and WVC1, so consequently WMVA is handled by a different

DirectShow DirectShow (sometimes abbreviated as DS or DShow), codename Quartz, is a multimedia framework and API produced by Microsoft for software developers to perform various operations with media files or streams. It is the replacement for Microsoft's ea ...

decoder than WVC1. Some 3rd party hardware and software decoders only decode WMVA based content. As of 2006, WMVA is considered a deprecated codec because it is not fully VC-1 compliant.

WVC1

WVC1, also known as Windows Media Video 9 Advanced Profile, implements a more recent and fully compliant Advanced Profile of the VC-1 codec standard. It offers support for interlaced content and is transport independent. With the previous version of the Windows Media Video 9 Series codec, users could deliver progressive content at data rates as low as one-third that of the MPEG-2 codec and still get equivalent or comparable quality to MPEG-2. The Windows Media Video 9 Advanced Profile codec also offers this same improvement in encoding efficiency with interlaced contents. A decoder for WVC1 is included in Windows Media Player 11, which is bundled with Windows Vista and is available as a download for Windows XP. This implementation is supported in Microsoft Silverlight.

Profiles

Bit rates and resolutions

Other implementations

Due to its origins in Microsoft's WMV9 codec, the most popular implementations of VC-1 encoders have so far been done by Microsoft, though third-party implementations exist as well. Sonic Cinevision PSE, a professional VC-1 encoding tool used predominantly in

and

Blu-ray The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of st ...

encoding, is a commercial version of Microsoft's PEP (Parallel Encoder) encoding tool and VC-1 Analyzer tool. Microsoft owns the code development whereas

Sonic Solutions Sonic Solutions was an American computer software company headquartered in Novato, California. In addition to having a number of offices in the U.S., the company also maintained offices in Europe and Asia. It was acquired by Rovi Corporation in 20 ...

owns the sales and distribution. Microsoft also provides a separate VC-1 Encoder SDK which allows any company or software developer to integrate VC-1 encoding into their applications. Non-Microsoft VC-1 implementations (based entirely on the SMPTE specifications) have been done by Ericsson Television and MainConcept. The

project includes a free VC-1 decoder.

Encoding software

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

9 Series encodes VC-1 compliant video files, including WVC1

FourCC A FourCC ("four-character code") is a sequence of four bytes (typically ASCII) used to uniquely identify data formats. It originated from the OSType or ResType metadata system used in classic Mac OS and was adopted for the Amiga/Electronic Arts I ...

media. Windows Media Format 11 Runtime or Windows Media Player 11 must be installed on the computer to ensure full VC-1 compliance across all three profiles (Simple, Main and Advanced). If either of these are installed,

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, 2001 ...

can also save VC-1 compliant videos, as can any other application built on the Windows Media Format SDK or Windows Media Codec DMOs. A Windows Media Encoder Studio Edition was initially announced for professional encoding but later cancelled by Microsoft. Microsoft Expression Encoder which is part of

Expression Studio Microsoft Expression Studio is a discontinued suite of tools for designing and building Web and Windows client applications and rich digital media content. Overview Microsoft introduced Microsoft Expression on September 16, 2005, at Microsoft's ...

supports encoding VC-1 video to the Windows Media (

ASF ASF may refer to: Arts and entertainment * Alabama Shakespeare Festival, a drama festival * ''Asimov's Science Fiction'', a U.S.-based English-language science fiction magazine containing SF stories Science and technology Biological * A ...

) file format and the IIS Smooth Streaming format. Video encoder products made by Inlet, Digital Rapids, Harmonic, Envivio, Elemental Technologies, Anystream,

Telestream Telestream, Inc. is an American privately held computer software company. History The company, founded in 1998, is headquartered in Nevada City, California with personnel in France, Germany, Sweden, Poland, Canada and the UK. Telestream prov ...

and Rhozet support VC-1 encoding (based on the Microsoft VC-1 Encoder SDK) for IPTV and Web streaming.

Hardware-based encoding and decoding

Because VC-1 encoding and decoding requires significant computing power, software implementation that run on a general-purpose CPU are typically slow, especially when dealing with HD video content. To reduce CPU usage or to do real-time encoding, special-purpose hardware may be employed, either for the complete encoding or decoding process, or for acceleration assistance within a CPU-controlled environment. A hardware VC-1 encoder can be an ASIC or an FPGA. Hardware-accelerated (also known as hardware-assisted) video decoding can either be done on dedicated, special-purpose hardware or on generic, multi-purpose hardware such as

GPU A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobi ...

s. The former is typically found in consumer electronics devices such as Blu-ray Disc players and 3G/4G mobile phones, while the latter is typically found in PCs. Nearly all video cards manufactured since 2006 support some level of GPU-accelerated VC-1 decoding on the Windows platform via

DirectX Video Acceleration DirectX Video Acceleration (DXVA) is a Microsoft API specification for the Microsoft Windows and Xbox 360 platforms that allows video decoding to be hardware-accelerated. The pipeline allows certain CPU-intensive operations such as iDCT, motion ...

APIs. The native Windows WMV9/VC-1 decoder (wmvdecod.dll) only supports DXVA profiles A, B and C, while 3rd party VC-1 decoders such as

CyberLink CyberLink Corp. () is a Taiwanese multimedia software company headquartered in New Taipei City, Taiwan. Its products include PC and mobile applications for playback of movies and media, editing of videos and photos, and disc burning and backup s ...

's support the full DXVA Profile D decode acceleration. There is no support for GPU-accelerated VC-1 decode on the MacOS platform.

hardware prior to Raspberry Pi 4 supports VC-1 hardware-accelerated decoding, although it requires purchasing of a license key.

Legal status

Although heavily associated with

, there are 18 member companies within the VC-1

patent pool In patent law, a patent pool is a consortium of at least two companies agreeing to cross-license patents relating to a particular technology. The creation of a patent pool can save patentees and licensees time and money, and, in case of blocking ...

. The majority of patents are held by four companies: Microsoft (324 patents),

(122 patents),

(96 patents), and

(96 patents). As an SMPTE standard, VC-1 is open to implementation by anyone, although implementers may be required to pay licensing fees to the

MPEG LA MPEG LA is an American company based in Denver, Colorado that licenses patent pools covering essential patents required for use of the MPEG-2, MPEG-4, IEEE 1394, VC-1, ATSC, MVC, MPEG-2 Systems, AVC/H.264 and HEVC standards. History MPEG LA ...

, the LLC licensing body or directly to its members, who claim to hold

essential patent An essential patent or standard-essential patent (SEP) is a patent that claims an invention that must be used to comply with a technical standard. Standards organizations, therefore, often require members disclose and grant licenses to their paten ...

s on the format (since it is a non-exclusive licensing body). Over 61% of the patents have expired as of November 2022.

Patent holders

The following organizations hold one or more patents in the VC-1 patent pool, as listed by

References

External links

* *
VC-1 reference software analysis
at the MultimediaWiki * – IETF RTP Payload Format for Video Codec 1 * for the Raspberry Pi {{DEFAULTSORT:Vc-1 American inventions HD DVD High-definition television Japanese inventions Microsoft initiatives Open standards covered by patents Microsoft Silverlight SMPTE standards South Korean inventions Video codecs Video compression