VC-1

Key takeaways

VC-1 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect VC-1 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of VC-1 from memory before moving on to harder problems.

Reference excerpt

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, it was officially approved as an SMPTE 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 patents that applied to the technology, including Panasonic, LG Electronics and Samsung Electronics. VC-1 is supported in the now-deprecated Microsoft Silverlight, the briefly-offered HD DVD 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, H.262/MPEG-2 Part 2, H.263, and MPEG-4 Part 2. It was widely characterized as an alternative to the ITU-T and MPEG 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 format. Both HD DVD and Blu-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. Microsoft designated VC-1 as the Xbox 360 video game console'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 console and the FFmpeg project also includes a VC-1 decoder. On August 24, 2012, the Raspberry Pi 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."

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 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 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. 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 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 and Sonic 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 by Ericsson Television and MainConcept. The FFmpeg project includes a free VC-1 decoder.

Encoding software Windows Media Encoder 9 Series encodes VC-1 compliant video files, including WVC1 FourCC 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 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 and Rhozet support VC-1 encoding (based on the Microsoft VC-1 Encoder SDK) for IPTV and Web streaming.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with VC-1

Start with the simplest possible case. Write down what VC-1 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to VC-1 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about VC-1 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of VC-1

In research: VC-1 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses VC-1 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: VC-1 is common in secondary-school and first-year university syllabi. It links to neighbouring topics American inventions, HD DVD, High-definition television, so understanding it makes those chapters shorter.
In everyday life: Look for VC-1 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study VC-1 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what VC-1 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain VC-1 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is VC-1 in simple terms?

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.

Why does VC-1 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study VC-1?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on VC-1.