View source for MPEG-4 SLS

{{Short description|Extension to the MPEG-4 Audio standard}}
{{Infobox file format
| name                   = Scalable Lossless Coding
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| owner                  = [[International Organization for Standardization|ISO]]
| released               = {{start date and age|2006|06|df=y}}
| latest_release_version = ISO/IEC 14496-3:2019
| latest_release_date    = {{start date and age|2019|12|df=y}}
| type                   = [[Lossless compression|Lossless]] [[Audio file format|audio]]
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| contained by           = [[MP4]]
| extended from          =
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| standard               = [[MPEG-4 Part 3|ISO/IEC 14496-3]]
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| open                   = Yes
| free                   = No
}}
{{Infobox file format
| name          = MPEG4-SLS
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| extension     = .m4a
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[[File:Mpeg4sls.svg|right]]'''MPEG-4 SLS''', or '''MPEG-4 Scalable to Lossless''' as per [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] 14496-3:2005/Amd 3:2006 ('''Scalable Lossless Coding'''),<ref name="mpeg4audio-iso-sls">{{cite web | url=http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?csnumber=43362 | title=Scalable Lossless Coding (SLS) - ISO/IEC 14496-3:2005/Amd 3:2006 | author=ISO | author-link=International Organization for Standardization | publisher=ISO | year=2006 | access-date=2009-10-07}}</ref> is an extension to the [[MPEG-4 Part 3]] ([[MPEG-4]] Audio) standard to allow [[Lossless data compression|lossless]] [[Audio data compression|audio compression]] scalable to [[lossy]] MPEG-4 General Audio coding methods (e.g., variations of [[Advanced Audio Coding|AAC]]). It was developed jointly by the Institute for Infocomm Research (I<sup>2</sup>R) and [[Fraunhofer Society|Fraunhofer]], which commercializes its implementation of a limited subset of the standard under the name of '''HD-AAC'''. Standardization of the HD-AAC profile for MPEG-4 Audio is under development (as of September 2009).<ref name="iso-hda-aac">{{cite web | url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=53944 | title=ISO/IEC 14496-3:2009/FDAmd 1 - HD-AAC profile and MPEG Surround signaling | author=ISO | author-link=International Organization for Standardization | publisher=ISO | date=2009-09-11 | access-date=2009-10-09}}</ref><ref name="multimediawiki">{{cite web | url=http://wiki.multimedia.cx/index.php?title=MPEG-4_SLS | title=MPEG-4 SLS and HD-AAC profile | author=MultimediaWiki | publisher=MultimediaWiki | year=2009 | access-date=2009-10-09}}</ref>
MPEG-4 SLS allows having both a [[lossy]] layer and a lossless correction layer similar to [[Wavpack]] Hybrid, [[OptimFROG]] DualStream and [[DTS-HD Master Audio]], providing backwards compatibility to [[MPEG]] [[Advanced Audio Coding|AAC]]-compliant [[bitstream]]s. MPEG-4 SLS can also work without a lossy layer (a.k.a. "SLS Non-Core"), in which case it will not be backwards compatible,<ref name="sls-chiariglione">{{cite web|title=MPEG-4 Scalable Lossless Coding - ISO/IEC JTC1/SC29/WG11 N7707|url=http://mpeg.chiariglione.org/technologies/mpeg-4/mp04-sls/index.htm|author=Ralf Geiger, Rongshan Yu|date=October 2005|publisher=chiariglione.org|url-status=dead|archive-url=https://web.archive.org/web/20100430191710/http://mpeg.chiariglione.org/technologies/mpeg-4/mp04-sls/index.htm|archive-date=30 April 2010|access-date=2009-10-09}}</ref> [[Lossy compression]] of files is necessary for files that need to be streamed to the Internet or played in devices with limited storage.
With [[digital rights management]] (DRM), ripping of the lossless data or playback on non-DRM-enabled devices could be disabled.
MPEG-4 SLS is not related in any way to [[MPEG-4 ALS]] (Audio Lossless Coding).
==Background==
New lossless audio coding technologies that need higher bandwidth and larger storage capacities may now be appropriate for many applications and have been gaining attention in recent years. In addressing this need, [[MPEG]] issued a Call for Proposals (CfP) in October 2002 to solicit a technology that could address all these needs.
The CfP requested proposals for a [[lossless]] and scalable technology that was backward compatible with the existing MPEG [[Advanced Audio Coding|AAC]] [[codec]], and could operate efficiently at several different sampling rates and word length combinations. Institute for Infocomm Research ([https://web.archive.org/web/20080105162002/http://www.i2r.a-star.edu.sg/ I2R]) technologies were adopted for the scalable to lossless coding (14496-3/AMD5) architecture Reference Model 0.
I2R offers a fully scalable to lossless audio coding solution. On top of the core AAC codec, a scalable extension layer increases the signal-to-noise ratio, reaching lossless quality at data rates comparable to those of current pure lossless audio codecs, that is, at average compression ratios of about 58%.
The scalability of the extension makes this combination a coding solution for production environments, where the result is to be transmitted to several recipients through channels of differing [[Bandwidth (computing)|bandwidth]]. Furthermore, for private and professional use in music archives, this enables storing the original music data and transferring compressed copies (e.g. to portable devices) without transcoding.
== Licensing ==
The Licensing Administrator for the MPEG-4 Audio [[patent pool]] is Via Licensing Corporation. Licensors offering their SLS patents through the Via Licensing Corporation's licensing program include [[Agency for Science, Technology and Research|A*STAR Exploit Technologies Pte Ltd]] (Singapore), Fraunhofer IIS (Germany), and [[Nippon Telegraph and Telephone]] Corporation (Japan).<ref name="reuters">{{cite web|title=Via Licensing Announces MPEG-4 SLS Patent Pool License|url=https://www.reuters.com/article/pressRelease/idUS137433+05-Jan-2009+BW20090105|author=Business Wire|date=2009-01-05|publisher=Reuters|url-status=dead|archive-url=https://web.archive.org/web/20120726235539/https://www.reuters.com/article/pressRelease/idUS137433+05-Jan-2009+BW20090105|archive-date=26 July 2012|access-date=2009-10-09}}</ref><ref name="via-businesswire">{{cite web|title=Via Licensing Announces the Availability of an MPEG-4 SLS Joint Patent Licensing Program|url=http://www.businesswire.com/portal/site/home/permalink/?ndmViewId=news_view&newsId=20090512006643&newsLang=en|author=Via Licensing Corporation|date=2009-05-12|publisher=Business Wire|url-status=dead|archive-url=https://web.archive.org/web/20110606042731/http://www.businesswire.com/portal/site/home/permalink/?ndmViewId=news_view&newsId=20090512006643&newsLang=en|archive-date=6 June 2011|access-date=2009-10-09}}</ref>
The licensing fees varies - e.g. a licensee shall pay $0.098 to the Via Licensing Corporation for each copy of PC software decoder sold or supplied.<ref name="via-fees">{{cite web|title=MPEG-4 SLS (Scalable to Lossless) - License Fees|url=http://www.vialicensing.com/licensing/SLS_fees.cfm|author=Via Licensing Corporation|year=2009|publisher=Via Licensing Corporation|url-status=dead|archive-url=https://web.archive.org/web/20090130132055/http://www.vialicensing.com/licensing/SLS_fees.cfm|archive-date=30 January 2009|access-date=2009-10-09}}</ref>
== Releases ==
In 2011, Los Angeles based hip hop group [[People Under The Stairs]] released ''Highlighter'', the first commercial HD-AAC release taken directly from 24 to 48 session files, encoded and sold directly to fans via the website [https://web.archive.org/web/20151009132826/http://pl70.net/ PL70.net]<ref name="release info">{{cite web | url=http://www.pl70.net/highlighter-hd-aac.com | title=Piecelock 70 annonce Highlighter HD release}}</ref>
== See also ==
* [[Bitrate peeling]], in [[Ogg Vorbis]]
* [[WavPack]], and [[OptimFROG DualStream]], other formats with lossy + correction
== References ==
{{Reflist}}
== External links ==
*[http://mpeg.chiariglione.org/technologies/mpeg-4/mp04-sls/index.htm International Organization for Standardization MPEG-4 SLS page]
*[http://wiki.multimedia.cx/index.php?title=MPEG-4_SLS MPEG-4 SLS - MultimediaWiki]
*[https://web.archive.org/web/20060629140035/http://www.iis.fraunhofer.de/amm/projects/mpeg4audio/index.html Fraunhofer]
*[https://web.archive.org/web/20110721090357/http://www.a-star.edu.sg/Media/News/PressReleases/tabid/828/articleType/ArticleView/articleId/1172/Default.aspx A-Star press release]
*[https://web.archive.org/web/20060925185829/http://www.iis.fraunhofer.de/amm/download/aes/dl.html?f=AES6183_MPEG-4_Scalable_to_Lossless_Audio_Coding.pdf Fraunhofer paper]
*[https://archive.today/20081120230416/http://www.hd-aac.com/ HD-AAC.com]
*[http://mpeg.chiariglione.org/ Official MPEG web site]
{{Compression formats}}
[[Category:MPEG-4]]
[[Category:Open standards covered by patents]]