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Windows Media Video 9 Series Codecs
In 2006, the Society of Motion Picture and Television Engineers (SMPTE) formally published the Final Specification for SMPTE 421M, also known as VC-1. Formal standardization of VC-1 represents the culmination of years of technical scrutiny by over 75 companies, leading to a codec that is well-documented, extremely stable, easily licensable, and accepted by the industry. VC-1 supports three profiles: Simple, Main, and Advanced. The Simple and Main profiles have been complete for several years, and existing implementations such as WMV 9 have long supported the creation and playback of content using these profiles, as well as an early implementation of the Advanced profile. The completion of the Advanced profile and consequent standardization of all profiles in VC-1 represents the final step in a comprehensive specification that delivers high definition content—either interlaced or progressive—across any medium and to any capable device.
The following video codecs are supported by the latest versions of Microsoft encoding applications and Windows Media Player, as well as by the Windows Media digital rights management platform. For more information about Windows Media Audio 9 Series codecs, see Encoding Audio and Video with Windows Media Codecs.
Windows Media Video 9
Simple and Main Profiles
Advanced Profile
Windows Media Video 9 Screen
Windows Media Video 9 Image Version 2
Windows Media Video 9 VCM
Compatibility
Windows Media Video 9Windows Media Video 9 is the Microsoft implementation of the VC-1 SMPTE standard. It supports Simple, Main, and Advanced profiles.
Simple and Main Profiles
The Windows Media Video 9 Simple and Main profiles fully conform to the SMPTE VC-1 standard and provide high-quality video for streaming and downloading. These profiles support 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. Windows Media Video 9 is already supported by a wide variety of players and devices.
Advanced Profile
The Windows Media Video 9 Advanced profile fully conforms to the SMPTE VC-1 standard, supports interlaced content, and is transport-independent. Content creators can use this profile to deliver either progressive or interlaced content at data rates as low as one-third that of the MPEG-2 codec—with the same quality as MPEG-2.
In the past, interlaced video content was always de-interlaced before encoding with the Windows Media Video codec. Now, encoding applications such as Windows Media 9 Series, and third-party encoding solutions can support compression of interlaced content without first converting it to progressive content. Maintaining interlacing in an encoded file is important if the content is ever rendered on an interlaced display, such as a television.
Transport independence also enables the delivery of Windows Media Video 9 Advanced Profile over systems that are not Windows Media-based, such as standards-based broadcast infrastructures (through native MPEG-2 transport streams), wireless infrastructures (using real-time transfer protocol [RTP]), or even DVDs.
Get more information about using advanced profile settings.
The following table compares Windows Media Video 9 Advanced Profile to competing compression technology.
| Video Data | Industry Compression* | Windows Media* | Compression Savings |
|---|
480/24p 720x480 pixels/frame x 8 bits per channel x 24 fps
| MPEG-2 at 4–6 Mbps
| Windows Media Video 9 Advanced Profile at 1.3–2 Mbps
| 3:1
| 480/30i 720x480 pixels/frame x 8 bits per channel x 30 fps
| MPEG-2 at 6–8 Mbps
| Windows Media Video 9 Advanced Profile at 2–4 Mbps
| 2–3:1
| 720/24p 1280x720 pixels/frame x 8 bits per channel x 24 fps
| MPEG-2 at 19 Mbps
| Windows Media Video 9 Advanced Profile at 5–8 Mbps
| 2.4–3.8:1
|
*Content dependent
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Windows Media Video 9 ScreenThe Windows Media Video 9 Screen codec is optimized for compressing sequential screenshots and highly static video that is captured from the computer display, which makes it ideal for delivering demos or demonstrating computer use for training. The codec takes advantage of the typical image simplicity and relative lack of motion to achieve a very high compression ratio.
During the encoding process, the codec automatically switches between lossy and lossless encoding modes, depending on the complexity of the video data. For complex data, the lossless mode preserves an exact copy of the data. For less complex data, the lossy mode discards some data to achieve a higher compression ratio. By automatically switching between these two modes, the codec maintains video quality while maximizing compression.
Overall, the Windows Media Video 9 Screen codec delivers better handling of bitmap images and screen motion, even on relatively modest CPUs. It is also up to 100 times more efficient than the commonly-used run length encoding.
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Windows Media Video 9 Image Version 2The Windows Media Video 9 Image Version 2 codec is different from the other video codecs. Instead of processing uncompressed video, it transforms still images into video by using pan, zoom, and cross-fade transitions between clips to create an unlimited number of effects.
The results can then be delivered at data rates as low as 20 kilobits per second (Kbps). These files are compressed using either constant bit rate (CBR) or one-pass variable bit rate (VBR) modes.
 Note The Windows Media Video 9 Image Version 2 codec is not compatible with the Windows Media Video 9 Image codec.
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Windows Media Video 9 VCMThe Video Compression Manager (VCM) version of the Windows Media Video 9 Series codec enables earlier versions of encoding and editing applications to support the Windows Media Video 9 Series codec in file containers such as Audio Video Interleaved (AVI). This codec package also allows Windows Media Video (WMV) files based on Windows Media Format 9 Series to be played in Windows Media Player 6.4, in both ASF and AVI file containers.
To learn more about VCM, review the VCM FAQs.
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CompatibilityThe following table outlines what your audience will experience when playing Windows Media Video 9 Series content on earlier Microsoft Windows operating systems or with earlier versions of Windows Media Player. This table also lists the compatibility for Apple Mac OS X and Windows CE–based platforms.
| Codec | Feature | Player backward compatibility |
|---|
Windows Media Video 9
| General
| Windows Media Player 6.4 or later
Windows Media Player 9 for Mac OS X
Windows Media Player 9 Series and Windows Media Player 9.1 for Pocket PC*
Windows Media Player 9 Series and Windows Media Player 9.1 for Smartphone*
|
| Frame Interpolation
| Requires Windows Media Player 9 Series (or Software Development Kit) or later and Windows XP.
| Windows Media Video 9 Advanced Profile
| General
| Windows Media Player 7 or later
| Windows Media Video 9 Screen
| General
| Windows Media Player 7 or later
| Windows Media Video 9 Image Version 2
| General
| Windows Media Player 7 or later
|
*All versions of Windows Media Player for Pocket PC and Smartphone are shipped as part of the Microsoft Windows Mobile operating system. Windows Media Player for Pocket PC and Windows Media Player for Smartphone are not available for download from Microsoft.
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