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Active Streaming Format

The earlier name for Microsoft's Advanced Systems Format. See Windows Media formats.

Windows Media formats

Windows Media formats are supported in many software and hardware-based players as well as Microsoft's own software-based Windows Media Player. The foundation container format for Windows Media is the Advanced Systems Format (ASF) file, which holds audio, video, meta-data (titles, author, etc.), indexes and scripts.

WMA (Audio) and WMV (Video)
When Windows Media audio codecs are used, the resulting file is given a .WMA extension. When Windows Media video codecs are used, files have a .WMV extension. For non-Windows codecs, the .ASF file extension is used, and WMA and WMV files can be renamed with the .ASF extension for compatibility with earlier players. See WMA Lossless.

Windows Media audio and video files can be downloaded intact and played, or they can be streamed from a website when used in conjunction with Microsoft's Windows Media Services on a Web server. In fact, ASF originally stood for "Active Streaming Format," but was changed to Advanced Systems Format to eliminate the streaming-only connotation. See Smooth Streaming.

Metafile Formats
Windows Media provides XML-based metafile formats for holding playlists, content descriptions and the location of the ASF, WMA or WMV file on a local or remote server. These files are called "redirectors" (see below). See Windows Media Services, Windows Media Rights Manager and Windows Media.


 Extension  Medium

 Windows Native A/V Formats

 WAV     Audio (lossless)
 AVI     Video
 ASF     A/V non Windows codec
 WMA     Audio (regular & streaming)
 WMA     Audio Lossless (see WMA Lossless)
 WMV     Video (regular & streaming)

 Windows Metafile Formats (Redirectors)

 ASX     All formats
 WAX     WMA files
 WVX     WMV files
 WPL     Client-side playlist

 Non-Windows Formats Supported by
 Windows Media Player

 MP3     MPEG audio
 AU      Unix audio
 SND     Unix audio
 AIFF    Macintosh audio
 MID     MIDI music
 RMI     MIDI music
 MOV     QuickTime video
 QT      QuickTime video
 MPG     MPEG video
 MPE     MPEG video
 VOB     DVD

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