WMV
WMV - Windows Media Video
WMV stands for Windows Media Video -- developed and controlled by Microsoft. WMV is a generic name of Microsoft's video encoding solutions and doesn't necessarily define the technology what it uses -- since version 7 (WMV7) Microsoft has used its own flavour of MPEG-4 video encoding technology (not very surprising, it's not compatible with other MPEG-4 technologies..). DivX ;-) video format is originally based on hacked WMV codec. The only difference between ASF files and WMV or WMA files are the file extensions and the MIME types. The MIME type for a WMV file is video/x-ms-wmv, and for WMA it is audio/x-ms-wma. The MIME type for ASF is video/x-ms-asf. The basic internal structure of the files is identical.
The change in extensions was made to make it easier for an application to identify the content of a media file. A .wma file extension designates a file containing only audio. A .wmv extension designates a file containing both video and audio. Microsoft, seeking to become a vital player in the budding world of digital media, a host of software products intended to ensure its influence over music and video. Digital media such as MP3 music files or streams of video sent over the Internet must be created, edited, encrypted, encoded, indexed and distributed, and Microsoft has software involved in all these tasks.
One key part of that plan is Microsoft's Windows Media Video (WMV) format, a new way to encode video that has been under development for years and is reaching completion. Freezing the format will make it possible to encode and decode files without having to worry about whether the file will be out of date in a few months. That could reduce the reluctance of business partners to target their products to the WMV format.
Audio and video formats may sound like an obscure byway of the computing technology landscape. But they are the center of an interconnected web of technologies that spans the computing industry. Media formats help Microsoft extend its dominance in the PC market to other areas, an issue that's at the center of the ongoing antitrust trials.
Video information currently is encoded with several formats: MPEG-2 (used on digital cable TV set-top boxes), MPEG-4, Apple Computer's QuickTime format and other methods. But Microsoft, through the potent distribution channel that is Windows, has an immediate advantage over many competitors in finding a way to propagate its own formats. More than 90 percent of the world's PCs run the Windows operating system.
It's a tactic familiar to Microsoft with its Windows Media Audio (WMA) format, whose particulars the company locked down three years ago. Where the competing MP3 audio format once was dominant, Microsoft has made major inroads with WMA, including support for the format in 110 devices such as car stereos.
Microsoft also is advocating use of its Windows Media Container file format, which goes by the initials ASF and can contain audio and video information as well as pictures such as album art, text such as playlists, and small programs called scripts.
Microsoft also plans to reiterate an argument it made in the struggle to get WMA to catch on: economics. WMV is more efficient than MPEG-4 in encoding video, letting three movies fit on a single DVD.
Windows Media file
A file containing audio, video, or script data that is stored in Windows Media Format. Depending on their content and purpose, Windows Media files use a variety of file name extensions, such as: .wma, .wme, .wms, .wmv, .wmx, .wmz, or .wvx. |
