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SMPTE
SMPTE
421M, informally known as VC-1, is a video coding format. It was initially developed as the proprietary video format Windows Media Video 9 by Microsoft
Microsoft
in 2003 and officially approved as a SMPTE
SMPTE
video codec standard on April 3, 2006. It is today a supported standard found in Blu-ray
Blu-ray
Discs, Microsoft's Silverlight
Silverlight
framework, and the now-discontinued HD DVD.

Contents

1 Format 2 Microsoft
Microsoft
codec implementations

2.1 WMV3 2.2 WMVA 2.3 WVC1

3 Profiles 4 Bit rates and resolutions 5 Other implementations 6 Encoding software 7 Hardware-based encoding and decoding 8 Legal status 9 See also 10 References 11 External links

Format[edit] VC-1 is an evolution of the conventional DCT-based video codec design also found in H.261, MPEG-1
MPEG-1
Part 2, H.262/ MPEG-2
MPEG-2
Part 2, H.263, and MPEG-4 Part 2. It is widely characterized as an alternative to the ITU-T and MPEG
MPEG
video codec standard known as H.264/ MPEG-4 AVC. VC-1 contains coding tools for interlaced video sequences as well as progressive encoding. The main goal of VC-1 Advanced Profile development and standardization was to support the compression of interlaced content without first converting it to progressive, making it more attractive to broadcast and video industry professionals. Both HD DVD
HD DVD
and Blu-ray Disc
Blu-ray Disc
have adopted VC-1 as a video standard, meaning their video playback devices will be capable of decoding and playing video-content compressed using VC-1. Windows Vista
Windows Vista
partially supports HD DVD
HD DVD
playback by including the VC-1 decoder and some related components needed for playback of VC-1 encoded HD DVD movies.[1] Microsoft
Microsoft
has designated VC-1 as the Xbox 360
Xbox 360
video game console's official video format, and game developers may use VC-1 for full motion video included with games. By means of an October 31, 2006 update, all formats of Windows Media Video
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
Windows Media Player
11. VC-1 is supported in the PlayStation 3
PlayStation 3
console and the FFmpeg
FFmpeg
project includes a VC-1 decoder.[2] On August 24, 2012, the Raspberry Pi
Raspberry Pi
Foundation announced hardware decoding support for VC-1.[3] Microsoft
Microsoft
codec implementations[edit] The VC-1 codec specification has so far been implemented by Microsoft in the form of 3 codecs, each identified with a unique four character code.[4] WMV3[edit] 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 in the YUV 4:2:0 color space, the deprecated interlaced mode was implemented in the less common YUV 4:1:1 color space. The Windows Media Video
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."[5] A number of high definition movies and videos have been released commercially in a format dubbed WMV HD. These titles are encoded with WMV3 Main Profile @ High Level (MP@HL). WMVA[edit] 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
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 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[edit] WVC1, also known as Windows Media Video
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
Windows Media Video
9 Series codec, users could deliver progressive content at data rates as low as one-third that of the MPEG-2
MPEG-2
codec and still get equivalent or comparable quality to MPEG-2[citation needed]. The Windows Media Video 9 Advanced Profile codec also offers this same improvement in encoding efficiency with interlaced contents[citation needed]. A decoder for WVC1 is included in Windows Media Player
Windows Media Player
11, which is bundled with Windows Vista
Windows Vista
and is available as a download for Windows XP. This implementation is supported in Microsoft
Microsoft
Silverlight. Profiles[edit]

Simple Main Advanced

Baseline intra frame compression Yes Yes Yes

Variable-sized transform Yes Yes Yes

16-bit transform Yes Yes Yes

Overlapped transform Yes Yes Yes

4 motion vector per macroblock Yes Yes Yes

¼ pixel luminance motion compensation Yes Yes Yes

¼ pixel chrominance motion compensation No Yes Yes

Start codes No Yes Yes

Extended motion vectors No Yes Yes

Loop filter No Yes Yes

Dynamic resolution change No Yes Yes

Adaptive macroblock quantisation No Yes Yes

B frames No Yes Yes

Intensity compensation No Yes Yes

Range adjustment No Yes Yes

Field and frame coding modes No No Yes

GOP Layer No No Yes

Display metadata No No Yes

Simple Main Advanced

Bit rates and resolutions[edit]

Profile Level Maximum Bit Rate Resolution / Framerate

Simple Low 96 kbit/s 176 × 144 / 15 (QCIF)

Medium 384 kbit/s 240 × 176 / 30 352 × 288 / 15 (CIF)

Main Low 2 Mbit/s 320 × 240 / 24 (QVGA)

Medium 10 Mbit/s 720 × 480 / 30 (480p) 720 × 576 / 25 (576p)

High 20 Mbit/s 1920 × 1080 / 30 (1080p)

Advanced L0 2 Mbit/s 352 × 288 / 30 (CIF)

L1 10 Mbit/s 720 × 480 / 30 (NTSC-SD) 720 × 576 / 25 (PAL-SD)

L2 20 Mbit/s 720 × 480 / 60 (480p) 1280 × 720 / 30 (720p)

L3 45 Mbit/s 1920 × 1080 / 24 (1080p) 1920 × 1080 / 30 (1080i) 1280 × 720 / 60 (720p)

L4 135 Mbit/s 1920 × 1080 / 60 (1080p) 2048 × 1536 / 24

Other implementations[edit] 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 HD DVD and Blu-ray
Blu-ray
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
owns the sales and distribution. Microsoft
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
Microsoft
VC-1 implementations (based entirely on the SMPTE
SMPTE
specifications) have been done by Tandberg Television and MainConcept.[6] The FFmpeg
FFmpeg
project includes a free VC-1 decoder.[2][7] Encoding software[edit] Windows Media Encoder 9 Series encodes VC-1 compliant video files, including WVC1 FourCC media. Windows Media Format 11 Runtime or Windows Media Player
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
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
Microsoft
Expression Encoder which is part of Expression Studio supports encoding VC-1 video to the Windows Media (ASF) file format and the IIS Smooth Streaming format. Video encoder products made by Inlet, Digital Rapids, Harmonic, Envivio, Elemental Technologies, Anystream, Telestream
Telestream
and Rhozet support VC-1 encoding (based on the Microsoft
Microsoft
VC-1 Encoder SDK) for IPTV and Web streaming. Hardware-based encoding and decoding[edit] 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 GPUs. The former is typically found in consumer electronics devices such as Blu-ray Disc
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 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's support the full DXVA Profile D decode acceleration. There is no support for GPU-accelerated VC-1 decode on the MacOS platform. Raspberry Pi
Raspberry Pi
hardware supports VC-1 hardware-accelerated decoding, although it requires purchasing of a license key.[8] Legal status[edit] Although widely considered to be Microsoft's product, there are 18 member companies within the VC-1 patent pool.[9] As an SMPTE
SMPTE
standard, VC-1 is open to implementation by anyone, although implementers may be required to pay licensing fees to the MPEG
MPEG
LA, the LLC licensing body or directly to its members, who claim to hold essential patents on the format (since it is a non-exclusive licensing body).[10] See also[edit]

Comparison of H.264 and VC-1 Video Compression VC-2 (Dirac)

References[edit]

^ " VC-1 Technical Overview". Windows Media. Microsoft. 2006. Retrieved October 5, 2006.  ^ a b "VC-1". Summer of Code. Google. Archived from the original on 2007-09-13. Retrieved 2007-03-21.  ^ " Raspberry Pi
Raspberry Pi
VC-1 Hardware Decoding". Raspberry Pi
Raspberry Pi
Foundation. 2012. Retrieved August 24, 2012.  ^ Sullivan, Gary J. (August 2010) [December 2007]. "DirectX Video Acceleration Specification for Windows Media Video
Windows Media Video
v8, v9 and vA Decoding (Including SMPTE
SMPTE
421M "VC-1")" (PDF). Microsoft
Microsoft
Developer Network (MSDN) Library, Windows Development Kit, Windows Driver Kit, Device and Driver Technologies, Display Devices (Adapters and Monitors), Design Guide, Windows 2000 Display Driver Model Design Guide. Microsoft. Retrieved 29 October 2010.  ^ "About the Windows Media Codecs". Microsoft
Microsoft
Developer Network. Microsoft. Retrieved 28 April 2014.  ^ " MainConcept
MainConcept
VC-1 Codec Package". MainConcept. Retrieved September 24, 2010.  ^ " FFmpeg
FFmpeg
Home/News". FFmpeg. March 9, 2007. Retrieved 29 October 2010. Nine months without news but with heavy development. A few select highlights are decoders for VC-1/WMV3/WMV9, VMware, VP5, VP6 video and WavPack, IMC, DCA audio and a WMA encoder.  ^ "New video features! MPEG-2
MPEG-2
and VC-1 decode, H.264 encode, CEC support". Raspberry Pi. Retrieved 2015-11-29.  ^ " VC-1 Licensors". MPEG-LA. Retrieved 2013-05-19.  ^ " MPEG
MPEG
LA, LLC. Press Release" (PDF). Archived from the original (PDF) on November 13, 2006. Retrieved August 17, 2006. 

External links[edit]

" VC-1 Profiles and Levels". VC-1. Retrieved December 12, 2005.  " Microsoft
Microsoft
WMV Codec Implementations". VC-1. Retrieved February 28, 2006.  VC-1 reference software analysis at the MultimediaWiki RFC 4425 – IETF
IETF
RTP Payload Format for Video Codec 1 " VC-1 Decode License Announcement". VC-1. Retrieved August 24, 2012.  for the Raspberry Pi

v t e

Multimedia
Multimedia
compression and container formats

Video compression

ISO/IEC

MJPEG Motion JPEG 2000 MPEG-1 MPEG-2

Part 2

MPEG-4

Part 2/ASP Part 10/AVC

MPEG-H

Part 2/HEVC

ITU-T

H.120 H.261 H.262 H.263 H.264 H.265

SMPTE

VC-1 VC-2 VC-3 VC-5

Alliance for Open Media

AV1

Others

Apple Video AVS Bink Cinepak Daala Dirac DV DVI FFV1 Huffyuv Indeo Lagarith Microsoft
Microsoft
Video 1 MSU Lossless OMS Video Pixlet ProRes 422 ProRes 4444 QuickTime

Animation Graphics

RealVideo RTVideo SheerVideo Smacker Sorenson Video, Spark Theora Thor VP3 VP6 VP7 VP8 VP9 WMV XEB YULS

Audio compression

ISO/IEC

MPEG-1
MPEG-1
Layer III (MP3) MPEG-1
MPEG-1
Layer II

Multichannel

MPEG-1
MPEG-1
Layer I AAC

HE-AAC AAC-LD

MPEG
MPEG
Surround MPEG-4 ALS MPEG-4 SLS MPEG-4 DST MPEG-4 HVXC MPEG-4 CELP MPEG-D USAC MPEG-H 3D Audio

ITU-T

G.711 (A-law, µ-law) G.718 G.719 G.722 G.722.1 G.722.2 G.723 G.723.1 G.726 G.728 G.729 G.729.1

IETF

Opus iLBC

3GPP

AMR AMR-WB AMR-WB+ EVRC EVRC-B EVS GSM-HR GSM-FR GSM-EFR

Others

ACELP AC-3 AC-4 ALAC Asao ATRAC CELT Codec2 DRA DTS FLAC iSAC Monkey's Audio TTA

True Audio

MT9 Musepack OptimFROG OSQ QCELP RCELP RealAudio RTAudio SD2 SHN SILK Siren SMV Speex SVOPC TwinVQ VMR-WB Vorbis VSELP WavPack WMA MQA aptX LDAC

Image compression

IEC, ISO, ITU-T, W3C, IETF

CCITT Group 4 GIF HEIF HEVC JBIG JBIG2 JPEG JPEG-LS JPEG
JPEG
2000 JPEG
JPEG
XR JPEG
JPEG
XT PNG TIFF TIFF/EP TIFF/IT

Others

APNG BPG DjVu EXR FLIF ICER MNG PGF QTVR WBMP WebP

Containers

ISO/IEC

MPEG-ES

MPEG-PES

MPEG-PS MPEG-TS ISO base media file format MPEG-4 Part 14 (MP4) Motion JPEG 2000 MPEG-21 Part 9 MPEG
MPEG
media transport

ITU-T

H.222.0 T.802

IETF

RTP

Others

3GP and 3G2 AMV ASF AIFF AVI AU BPG Bink

Smacker

BMP DivX Media Format EVO Flash Video GXF IFF M2TS Matroska

WebM

MXF Ogg QuickTime File Format RatDVD RealMedia RIFF

WAV

MOD and TOD VOB, IFO and BUP

Collaborations

NETVC MPEG-LA

See Compression methods for methods and Compression s

.