imported>Loserhead: Adding local short description: "Lossless audio coding format", overriding Wikidata description "lossless audio coding format"

2025-04-02T15:34:39Z

Adding local short description: "Lossless audio coding format", overriding Wikidata description "lossless audio coding format"

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{{Short description|Lossless audio coding format}}
{{Infobox file format
| name = Audio Lossless Coding
| icon =
| logo =
| screenshot =
| caption =
| extension =
| mime =
| type code =
| uniform type =
| magic =
| owner = [[International Organization for Standardization|ISO]]
| released = {{start date and age|2006|03|df=y}}
| latest_release_version = RM23
| latest_release_date = {{start date and age|2009|df=y}}
| type = [[Lossless compression|Lossless]] [[Audio file format|audio]]
| container for =
| contained by = [[MP4]]
| extended from =
| extended to =
| standard = [[MPEG-4 Part 3|ISO/IEC 14496-3]]
| url =
| open = Yes
| free = No
}}
'''MPEG-4 Audio Lossless Coding''', also known as '''MPEG-4 ALS''', is an extension to the [[MPEG-4 Part 3]] audio standard to allow [[Lossless data compression|lossless]] [[Audio data compression|audio compression]]. The extension was finalized in December 2005 and published as [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] 14496-3:2005/Amd 2:2006 in 2006.<ref name="iso-als">{{cite web | url=http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?csnumber=43026 | title=Audio Lossless Coding (ALS), new audio profiles and BSAC extensions – ISO/IEC 14496-3:2005/Amd 2:2006 | author=ISO | author-link=International Organization for Standardization | publisher=ISO | year=2006 | access-date=2009-10-07}}</ref> The latest description of MPEG-4 ALS was published as subpart 11 of the [[MPEG-4]] Audio standard (ISO/IEC 14496-3:2019) (5th edition) in December 2019.<ref name="isoiecfifth">{{cite web | url=https://webstore.iec.ch/preview/info_isoiec14496-3%7Bed5.0%7Den.pdf | title=ISO/IEC 14496-3:2019: Information technology — Coding of audio-visual objects — Part 3: Audio| author=ISO/IEC | author-link=International Organization for Standardization | publisher=ISO | year=2019 | access-date=2022-01-01}}</ref>

MPEG-4 ALS combines a short-term predictor and a long term predictor. The short-term predictor is similar to [[Free Lossless Audio Codec|FLAC]] in its operation – it is a quantized [[Linear predictive coding|LPC]] predictor with a losslessly coded residual using [[Golomb coding|Golomb Rice Coding]] or [[Block Gilbert Moore Coding]] (BGMC).<ref name="als-dcc">{{cite web |author1=Tilman Liebchen |author2=Yuriy Reznik |name-list-style=amp | title = MPEG-4 ALS: an Emerging Standard for Lossless Audio Coding | url = http://www.reznik.org/papers/DCC04_MPEG-ALS.pdf | format=PDF | access-date=2010-09-03 | date = 2004-04-03 | publisher=Data Compression Conference}}</ref><ref name="als-berlin-technology">{{cite conference |author=Tilman Liebchen |author2=Takehiro Moriya |author3=Noboru Harada |author4=Yutaka Kamamoto |author5=Yuriy A. Reznik |title=The MPEG-4 Audio Lossless Coding (ALS) Standard – Technology and Applications |conference=119th Audio Engineering Society Convention, 2005 October 7–10 New York |publisher=Audio Engineering Society |url=http://elvera.nue.tu-berlin.de/files/0737Liebchen2005.pdf |format=PDF |access-date=2009-10-08 | date = 2005-08-03 |via=Technische Universität Berlin}}</ref> The long term predictor is modeled by 5 long-term weighted residues, each with its own lag (delay). The lag can be hundreds of samples. This predictor improves the compression for sounds with rich harmonics (containing multiples of a single fundamental frequency, locked in phase) present in many musical instruments and human voice.

== Features ==
* Support for [[PCM]] resolutions of up to 32-bit including floating-point
* Arbitrary sampling rates
* Multi-channel / multi-track support (up to 65536 channels)
* [[Streaming media|Streaming]]<ref name="ntt-overview">{{cite web |author1=Noboru Harada |author2=Takehiro Moriya |author3=Yutaka Kamamoto |name-list-style=amp | title = MPEG-4 ALS: Performance, Applications, and Related Standardization Activities | url = https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr200712sp3.html | access-date=2009-10-08 | date = 2009-05-07 | publisher=NTT Technical Review}}</ref>
* Seekable (fast random access to any part of the encoded data).
* Optional storage in [[MP4]] file format; can be multiplexed with video and other media content supported by the MP4 container.
* An MPEG-4 [[MPEG-4 Part 3#Audio Profiles|Audio profile]] "ALS Simple Profile",<ref>{{citation|url=http://kikaku.itscj.ipsj.or.jp/sc29/open/29view/29n10483t.doc |title=ISO/IEC 14496-3:200X/PDAM 2 – ALS Simple Profile and Transport of SAOC – N10826 |format=DOC |date=2009-07-03 |access-date=2009-10-15 |archive-url=https://web.archive.org/web/20140729155217/http://kikaku.itscj.ipsj.or.jp/sc29/open/29view/29n10483t.doc |archive-date=2014-07-29 }}</ref> invoked with "-sp1" in the reference encoder.<ref name="als-berlin">{{cite web | author = Communication Systems Group | title = MPEG-4 Audio Lossless Coding (ALS) | url = https://www.nue.tu-berlin.de/menue/forschung/forschungsgebiete/datenkompression_und_uebertragung/mpeg_4_audio_lossless_coding_als/parameter/en/ | access-date = 2019-03-21 | date = 2009-10-01 | publisher = Technische Universität Berlin | archive-date = 2019-03-21 | archive-url = https://web.archive.org/web/20190321095222/https://www.nue.tu-berlin.de/menue/forschung/forschungsgebiete/datenkompression_und_uebertragung/mpeg_4_audio_lossless_coding_als/parameter/en/ | url-status = dead }}</ref>

== Software support ==
{{As of|2020}}, there has not been wide acceptance of this format, possibly due to the lack of encoders and decoders available.<ref name="comparison-hydrogenaudio">{{cite web | author= Hydrogenaudio Knowledgebase | title = Lossless comparison | url = https://wiki.hydrogenaud.io/index.php?title=Lossless_comparison#MPEG-4_ALS | access-date=2022-01-01 | year = 2006 | publisher=Hydrogenaudio Knowledgebase}}</ref>

A [[Reference implementation (computing)|reference implementation]] of MPEG-4 ALS encoder and decoder (mp4als – e.g. mp4alsRM23) can be obtained at the MPEG-4 ALS homepage and it was also published as ISO/IEC 14496-5:2001/Amd 10:2007/Cor 3:2009.<ref name="als-berlin" />

There is a MPEG-4 ALS Decoder plugin for [[Winamp]] player.<ref name="winamp">{{cite web | title = MPEG-4 ALS Decoder plugin 1.00 for Winamp | url = http://www.free-codecs.com/download/MPEG4_ALS_Decoder_plugin_for_Winamp.htm | access-date=2009-10-08 | date = 2007-06-05 | publisher=Codecs.com}}</ref>

On November 11, 2009, the [[FFmpeg]] [[Open-source software|open source]] project gained an MPEG-4 ALS decoder in its development version.<ref name="ffmpeg">{{cite web|author=FFmpeg |title=FFmpeg-cvslog r20517 |url=http://lists.mplayerhq.hu/pipermail/ffmpeg-cvslog/2009-November/025367.html |access-date=2009-11-20 |date=2009-11-11 |publisher=FFmpeg |archive-url=https://web.archive.org/web/20100211213503/http://lists.mplayerhq.hu/pipermail/ffmpeg-cvslog/2009-November/025367.html |archive-date=2010-02-11 }}</ref> Only a subset of the format is currently supported.

== History ==
In July 2002, the [[Moving Picture Experts Group]] issued a call for proposals of lossless audio coding procedures to be sent in before December. Seven companies submitted their proposals which were examined taking into consideration compression efficiency, complexity and flexibility. By July 2003, [[Lossless Predictive Audio Compression]] (LPAC) was selected as the first draft for the future standard. The reference model was further developed under participation of [[Technische Universität Berlin]] (TUB), [[RealNetworks]], and [[Nippon Telegraph and Telephone]] (NTT).

== See also ==
* [[Lossless predictive audio compression]] (predecessor)
* [[Lossless Transform Audio Compression]] (pre-predecessor)
* [[MPEG-4 SLS]] (MPEG-4 Scalable Lossless Coding)
* [[MPEG-4]]

== References ==
{{Reflist}}

== External links ==
* [https://www.nue.tu-berlin.de/menue/forschung/forschungsgebiete/datenkompression_und_uebertragung/mpeg_4_audio_lossless_coding_als/parameter/en/ MPEG-4 ALS homepage – Technische Universität Berlin] {{Webarchive|url=https://web.archive.org/web/20190321095222/https://www.nue.tu-berlin.de/menue/forschung/forschungsgebiete/datenkompression_und_uebertragung/mpeg_4_audio_lossless_coding_als/parameter/en/ |date=2019-03-21 }}
* [http://wiki.multimedia.cx/index.php?title=MPEG-4_Audio_Lossless_Coding_(ALS) MPEG-4 Audio Lossless Coding (ALS) – MultimediaWiki]
* [https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr200712sp3.html MPEG-4 ALS: Performance, Applications, and Related Standardization Activities] – NTT (2007)
* [http://www.reznik.org/software.html#ALS Technical papers describing design of residual coding and quantization algorithms in MPEG-4 ALS codec]
* [https://web.archive.org/web/20070311052037/http://www.acnnewswire.net/article.asp?Art_ID=31029&lang= Announcement on ACN Newswire]
* [https://web.archive.org/web/20070314131227/http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=43026 Technical specifications (ISO/IEC 14496-3:2005/Amd 2:2006)] (not free)
* [http://mpeg.chiariglione.org/ Official MPEG web site]

{{Compression formats}}
{{Compression software implementations}}

[[Category:MPEG-4]]
[[Category:Lossless audio codecs]]

Audio Lossless Coding - Revision history

imported>Loserhead: Adding local short description: "Lossless audio coding format", overriding Wikidata description "lossless audio coding format"