| VC-1 | |
|---|---|
| Internet media type | video/vc1 |
| Developed by | SMPTE,Microsoft,Panasonic,LG,Samsung,etc. |
| Initial release | 24 February 2006; 19 years ago (2006-02-24) |
| Latest release | SMPTE ST 421:2013 8 October 2013; 12 years ago (2013-10-08) |
| Type of format | Video coding format |
| Extended from | WMV 9 |
| Standards | SMPTE ST 421 |
| Open format? | Yes |
| Free format? | No[1] |
SMPTE 421,[2] informally known asVC-1, is avideo coding format. Most of it was initially developed asMicrosoft's proprietary video formatWindows Media Video 9 in 2003. With some enhancements including the development of a new Advanced Profile, it was officially approved as anSMPTE standard on April 3, 2006. It was primarily marketed as a lower-complexity competitor to theH.264/MPEG-4 AVC standard. After its development, several companies other than Microsoft asserted that they heldpatents that applied to the technology, includingPanasonic,LG Electronics andSamsung Electronics.
VC-1 is supported in the now-deprecatedMicrosoft Silverlight, the briefly-offeredHD DVD disc format, and theBlu-ray Disc format.
VC-1 is an evolution of the conventional block-basedmotion-compensated hybrid video coding design also found inH.261,MPEG-1 Part 2,H.262/MPEG-2 Part 2,H.263, andMPEG-4 Part 2. It was widely characterized as an alternative to theITU-T andMPEG video codec standard known asH.264/MPEG-4 AVC. The Advanced Profile of VC-1 contains tools designed for codinginterlaced video sequences as well asprogressive 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 the1080i format.
BothHD DVD andBlu-ray Disc adopted VC-1 as a supported video format, meaning their video playback devices are required to be capable of decoding and playing video-content compressed using VC-1.Windows Vista 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.[3]
Microsoft designated VC-1 as theXbox 360video game console's official video format, and game developers could use VC-1 forfull 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 thePlayStation 3 console and theFFmpeg project also includes a VC-1 decoder.[4]
On August 24, 2012, theRaspberry Pi Foundation announced hardware decoding support for VC-1.[5]
The VC-1 codec specification has so far been implemented by Microsoft in the form of three codecs, each identified with a uniquefour character code.[6]
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 theYUV 4:2:0 color sampling scheme, the deprecated interlaced mode was implemented using the less commonYUV 4:1:1 sampling scheme.
TheWindows 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."[7]
WMVA was the original implementation of WMV Advanced Profile prior to the acceptance of the VC-1 draft by SMPTE. The codec was distributed withWindows 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 differentDirectShow 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 (renamed by Microsoft to Windows Media Video 9) 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[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 inWindows Media Player 11, which is bundled with Windows Vista and is available as a download for Windows XP. This implementation is supported inMicrosoft Silverlight.
| 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 |
| 1⁄4 pixel luminance motion compensation | Yes | Yes | Yes |
| 1⁄4 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 |
| Profile | Level | MaximumBit 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 2048 × 2048 / 30 |
There are no external implementations of WMV9/AV-1 encoders. For example, Sonic Cinevision PSE- a VC-1 encoding tool, has been written entirely by Microsoft itself. Microsoft owns the code andSonic Solutions was tasked with sales. Microsoft on its own (without relying on Sonic company) 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 byEricsson Television andMainConcept.[8] TheFFmpeg project includes afree VC-1 decoder.[4][9]
Windows Media Encoder 9 Series encodes VC-1 compliant video files, including WVC1FourCC 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 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 ofExpression Studio supports encoding VC-1 video to the Windows Media (ASF) file format and theIIS Smooth Streaming format.
Video encoder products made by Inlet,Digital Rapids,Harmonic, Envivio,Elemental Technologies,Anystream,Telestream and Rhozet support VC-1 encoding (based on the Microsoft VC-1 Encoder SDK) for IPTV and Web streaming.
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 withHD 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 anASIC or anFPGA.
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 asGPUs. The former is typically found in consumer electronics devices such asBlu-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 viaDirectX 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 asCyberLink'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 hardware prior to Raspberry Pi 4 supports VC-1 hardware-accelerated decoding, although it requires purchasing of a license key.[10]
Although heavily associated withMicrosoft, there are 18 member companies within the VC-1patent pool.[11] The majority of patents are held by four companies: Microsoft (324 patents),Panasonic (122 patents),LG Electronics (96 patents), andSamsung Electronics (96 patents).
As an SMPTE standard, VC-1 is open to implementation by anyone, although implementers may be required to pay licensing fees to theVia-LA, the LLC licensing body or directly to its members, who claim to holdessential patents on the format (since it is a non-exclusive licensing body).[12]
Over 94.7% of the patents have expired as of July 31, 2025.[11]
The following organizations hold one or more patents in the VC-1 patent pool, as listed byVia-LA.
This is adynamic list and may never be able to satisfy particular standards for completeness. You can help byadding missing items withreliable sources.
The following organizations hold one or more patents in the Via-LAVC-1 patent pool. LG has now removed their 1 remaining patent from the pool but it has been kept listed in the table below as it is still a valid patent.
| Organization | Active patents | Expired patents | Total patents |
|---|---|---|---|
| Microsoft | 51 | 421 | 472 |
| Panasonic | 4 | 118 | 122 |
| LG Electronics | 1 | 95 | 96 |
| Samsung Electronics | 2 | 94 | 96 |
| Dolby Laboratories | 2 | 102 | 104 |
| Philips | 0 | 77 | 77 |
| Hitachi | 0 | 60 | 60 |
| Mitsubishi Electric | 0 | 52 | 52 |
| Sony | 0 | 28 | 28 |
| JVC Kenwood | 0 | 25 | 25 |
| Toshiba | 0 | 21 | 21 |
| Fujitsu | 0 | 20 | 20 |
| Telenor | 0 | 19 | 19 |
| Siemens | 2 | 16 | 18 |
| AT&T Intellectual Property | 0 | 16 | 16 |
| Sun Patent Trust | 0 | 12 | 12 |
| Sharp Corporation | 0 | 8 | 8 |
| Orange S.A. | 0 | 7 | 7 |
| Nippon Telegraph and Telephone | 0 | 4 | 4 |
| Pantech | 0 | 4 | 4 |
| ZTE | 0 | 1 | 1 |
| Total (All Manufacturers) | 62 | 1200 | 1262 |
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.
