What is ASF file?

The ASF file type is primarily associated with Advanced Streaming Format by Microsoft Corporation. ASF is based on serialized objects which are essentially byte sequences identified by a GUID marker. ASF files often contain Windows Media Audio (.WMA) or Windows Media Video (.WMV) data.

The format specifies the structure of the video/audio stream. This is similar to the function performed by the QuickTime, AVI, or Ogg container formats. One of the objectives of ASF was to support playback from digital media servers, HTTP servers, and local storage devices such as hard disk drives.

An ASF file consists of three objects: a Header object containing information about the file itself, a Data object containing the media streams, and an optional Index object that can help support random access to data within the file.