Advanced Streaming Format

Advanced Streaming Format

Advanced Streaming Format (or ASF, later renamed into Advanced Systems Format) is Microsoft's proprietary digital audio/digital video wrapper, especially meant for streaming. ASF is part of the Windows Media framework.

The format does not specify how the video or audio should be encoded, but instead just specifies the structure of the video/audio stream. What this means is that ASF files can be encoded with basically any audio/video codec and still would be in ASF format. This is similar to the function performed by the QuickTime format or the Ogg format.

The most common contents of an ASF file is:

Windows Media Audio (WMA)
Windows Media Video (WMV)

ASF files can also contain metadata, such as the artist, title, album and genre for an audio track, or the director of a video track, much like the ID3 tags of MP3 files.

ASF files containg only WMA audio can be named with the file suffix .wva and files of only audio and video content may have the suffix .wmv. Both may use .asf as a suffix if desired.

Many cases ASF is confused with Microsoft's own implementation of MPEG-4 video format (Windows Media Video), because most of the ASF streams are encoded using this technology.

External links

Windows Media Formats