Audio Lossless Coding

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| name = Audio Lossless Coding

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| 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 audio

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| contained by = MP4

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| standard = ISO/IEC 14496-3

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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 audio compression. The extension was finalized in December 2005 and published as ISO/IEC 14496-3:2005/Amd 2:2006 in 2006.{{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}} 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.{{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}}

MPEG-4 ALS combines a short-term predictor and a long term predictor. The short-term predictor is similar to FLAC in its operation – it is a quantized LPC predictor with a losslessly coded residual using Golomb Rice Coding or Block Gilbert Moore Coding (BGMC).{{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}}{{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}} 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{{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}}
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 Audio profile "ALS Simple Profile",{{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 }} invoked with "-sp1" in the reference encoder.{{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 }}

Software support

{{As of|2020}}, there has not been wide acceptance of this format, possibly due to the lack of encoders and decoders available.{{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}}

A 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.

There is a MPEG-4 ALS Decoder plugin for Winamp player.{{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}}

On November 11, 2009, the FFmpeg open source project gained an MPEG-4 ALS decoder in its development version.{{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 }} 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).

References

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]

Category:MPEG-4

Category:Lossless audio codecs