# Advanced Systems Format > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Advanced_Systems_Format > Markdown URL: https://mediated.wiki/source/Advanced_Systems_Format.md > Source: https://en.wikipedia.org/wiki/Advanced_Systems_Format > Source revision: 1350303328 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|File format}} {{redirect-multi|4|.wmv|WMV file|.wma|WMA file|the video codec|Windows Media Video|the audio codec|Windows Media Audio}} {{Infobox file format | name = Advanced Systems Format | icon = Computer icons of for ASF, WMA and WMV files.png | icon_size = x64px | iconcaption = {{midsize|This image illustrates the computer icons that [Windows Vista](/source/Windows_Vista) displays for Advanced Systems Format, depending on the file name extension. From left to right, the icons correspond to {{mono|.asf}}, {{mono|.wma}}, and {{mono|.wmv}} files.}} | extension = .asf .wma .wmv | mime = video/x-ms-asf, application/vnd.ms-asf{{cite web|url=https://www.iana.org/assignments/media-types/application/vnd.ms-asf|publisher=[IANA](/source/Internet_Assigned_Numbers_Authority)|year=1997|author=Microsoft|author-link=Microsoft|title=Registration of MIME media type application/vnd.ms-asf|website=iana.org}} | magic = 30 26 B2 75 8E 66 CF 11 A6 D9 00 AA 00 62 CE 6C{{cite web |publisher=[Library of Congress](/source/Library_of_Congress)|work=Digital Preservation|date=2014-02-04|access-date=2014-03-12|url=https://www.digitalpreservation.gov/formats/fdd/fdd000067.shtml |title=ASF (Advanced Systems Format)}} | standard = | url = | type code = 'ASF_' | uniform type = com.microsoft.advanced-systems-format | owner = [Microsoft](/source/Microsoft) | type = [Container format](/source/Container_format_(digital)) | container for = [Windows Media Audio](/source/Windows_Media_Audio), [Windows Media Video](/source/Windows_Media_Video), [VC-1](/source/VC-1) | contained by = | extended from = | extended to = | released = Proprietary: {{start date and age|1996|09|16|df=y}}{{Cite web|title=Advanced Streaming Format|url=https://www.tech-insider.org/digital-video/research/1997/asf/index.htm|access-date=2021-12-13|website=Tech Insider}}{{Cite news|date=1996-09-16|title=Microsoft Introduces NetShow, A Platform for Delivering Multimedia Content Over Intranets|url=https://news.microsoft.com/1996/09/16/microsoft-introduces-netshow-a-platform-for-delivering-multimedia-content-over-intranets/|access-date=2021-12-13|website=Microsoft Stories}}
Public: {{start date and age|1998|02|26|df=y}}{{cite IETF |title=Advanced Streaming Format (ASF) Specification |draft=draft-fleischman-asf-01 |last1=Fleischman |first1=Eric |date=26 February 1998 |publisher=Internet Engineering Task Force |access-date=13 December 2021}} | latest_release_version = 01.20.03 | latest_release_date = {{start date and age|2004|12|df=y}} | open = Yes | free = No{{cite tech report |publisher=Library of Congress |location=Washington, D.C. |series=Sustainability of Digital Formats |type=Full draft |title=ASF (Advanced Systems Format) |date=6 April 2007 |url=https://www.loc.gov/preservation/digital/formats/fdd/fdd000067.shtml |access-date = 1 December 2021}} }} '''Advanced Systems Format''' (formerly '''Advanced Streaming Format''', '''Active Streaming Format''') is [Microsoft](/source/Microsoft)'s [proprietary](/source/Proprietary_software) [digital audio](/source/digital_audio)/[digital video](/source/digital_video) [container format](/source/container_format_(digital)), especially meant for [streaming media](/source/streaming_media). ASF is part of the [Media Foundation](/source/Media_Foundation) framework. ==Overview and features== ASF is based on [serialized](/source/serialization) ''[objects](/source/Object-oriented_programming)'' which are essentially [byte](/source/byte) sequences identified by a [GUID](/source/Globally_Unique_Identifier) marker. The format does not specify how (i.e. with which [codec](/source/codec)) the video or audio should be encoded; it just specifies the structure of the video/audio stream. This is similar to the function performed by the [QuickTime File Format](/source/QuickTime_File_Format), [AVI](/source/Audio_Video_Interleave), or [Ogg](/source/Ogg) formats. One of the objectives of ASF was to support playback from [digital media servers](/source/Streaming_media), [HTTP server](/source/HTTP_server)s, and local storage devices such as [hard disk drive](/source/hard_disk_drive)s. The most common media contained within an ASF file are [Windows Media Audio](/source/Windows_Media_Audio) (WMA) and [Windows Media Video](/source/Windows_Media_Video) (WMV). The most common file extensions for ASF files are extension {{samp|.WMA}} (audio-only files using Windows Media Audio, with MIME-type audio/x-ms-wma) and {{samp|.WMV}} (files containing video, using the Windows Media Audio and Video codecs, with MIME-type video/x-ms-asf). These files are identical to the old {{samp|.ASF}} files but for their extension and MIME-type. The different extensions are used to make it easier to identify the content of a media file.{{Cite web|url=http://support.microsoft.com/kb/284094|title=The Difference Between ASF and WMV/WMA Files}} ASF files can also contain objects representing [metadata](/source/Metadata_(computing)), such as the artist, title, album and genre for an audio track, or the director of a video track, much like the [ID3](/source/ID3) tags of [MP3](/source/MP3) files. It supports scalable media types and stream prioritization; as such, it is a format optimized for streaming. The ASF container provides the framework for [digital rights management](/source/digital_rights_management) in Windows Media Audio and Windows Media Video. An analysis of an older scheme used in WMA reveals that it is using a combination of [elliptic curve cryptography](/source/elliptic_curve_cryptography) key exchange, [DES](/source/Data_Encryption_Standard) block cipher, a custom block cipher, [RC4](/source/RC4_cipher) stream cipher and the [SHA-1](/source/SHA-1) hashing function. ASF container-based media are sometimes still streamed on the internet either through the [MMS](/source/Microsoft_Media_Services) protocol or the [RTSP](/source/Real_Time_Streaming_Protocol) protocol. Mostly, however, they contain material encoded for 'progressive download', which can be distributed by any webserver and then offers the same advantages as streaming: the file starts playing as soon as a minimum number of bytes is received and the rest of the download continues in the background while one is watching or listening. The [Library of Congress](/source/Library_of_Congress) Digital Preservation project considers ASF to be the ''de facto'' successor of [RIFF](/source/Resource_Interchange_File_Format). In 2010 [Google](/source/Google) picked RIFF as the container format for [WebP](/source/WebP). ==License== The specification is downloadable from the Microsoft website,{{Cite web|url=https://download.microsoft.com/download/7/9/0/790fecaa-f64a-4a5e-a430-0bccdab3f1b4/ASF_Specification.doc|title=ASF Specification Download}} and the format can be implemented under a [license](/source/license) from Microsoft that however does not allow distribution of sources and is not compatible with [open source](/source/Open-source_software) licenses. The author of the free software project [VirtualDub](/source/VirtualDub) reported that a Microsoft employee informed him that his software violated a Microsoft patent regarding ASF playback.{{citation |url=http://www.advogato.org/article/101.html |title=Advogato: Microsoft patents ASF media file format, stops reverse engineering |archive-url=https://web.archive.org/web/20170628194627/http://www.advogato.org/article/101.html |archive-date=2017-06-28 |access-date=2019-03-11 |url-status=dead }} Certain [error-correcting](/source/Error_detection_and_correction) techniques related to ASF were patented in the United States ([https://patents.google.com/patent/US6041345A/ United States Patent 6,041,345] Levi, et al. March 21, 2000) by Microsoft until August 10, 2019. ==See also== *[Audio Video Interleave](/source/Audio_Video_Interleave) (AVI) *[Comparison of container formats](/source/Comparison_of_container_formats) ==References== {{Reflist|2}} ==External links== *[https://msdn.microsoft.com/en-us/library/ms983668(loband).aspx An Overview of Advanced Systems Format] *[https://msdn.microsoft.com/en-us/library/dd757562(VS.85).aspx Overview of the ASF Format] *[https://www.digitalpreservation.gov/formats/fdd/fdd000067.shtml Library of Congress analysis of ASF format sustainability] *[https://avifile.sourceforge.net/docs.htm ASF Container Format - v2.0 (free available but unused) and v1.0 (reconstructed)] *[https://msdn.microsoft.com/en-us/library/ms983653(loband).aspx MSDN How To Embed Windows Media Player in a HTML Web Page (For Webmasters)] *[https://web.archive.org/web/20100315064515/http://www.microsoft.com/windows/windowsmedia/howto/articles/CustomizedExp.aspx Creating A Windows Media Custom Experience (For Webmasters)] {{Compression formats}} {{Internet Explorer}} {{DEFAULTSORT:Advanced System Format}} Category:Internet Explorer Category:Digital container formats Category:Microsoft Windows multimedia technology Category:Digital rights management systems --- Adapted from the Wikipedia article [Advanced Systems Format](https://en.wikipedia.org/wiki/Advanced_Systems_Format) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Advanced_Systems_Format?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.