View source for Apple Lossless Audio Codec

{{Short description|Lossless digital audio coding format}}
{{Infobox software
| name = Apple Lossless Audio Codec
| logo = 
| screenshot = 
| caption = 
| author = 
| developer = [[Apple Inc.|Apple]]
| released = {{start date and age|2004|04|28}}
| latest_release_version = {{Start date and age|2011|10|28}}
| latest_release_date = 
| latest preview version = 
| latest preview date = 
| operating_system = <!-- Do not forget your source -->
| genre = [[Audio codec]]
| license = [[Apache License]] 2.0
| website = {{URL|http://alac.macosforge.org}}
}}
{{Infobox file format
| name = 
| logo =
| screenshot =
| caption =
| extension = [[.m4a]] [[Core Audio Format|.caf]]
| mime =
| type code =
| uniform type =
| magic =
| owner = [[Apple Inc.]]
| type = [[Lossless compression|Lossless]] [[Audio file format|audio]]
| container for =
| contained by = [[MPEG-4 Part 14]]
| extended from =
| extended to =
| standard =
| open = Yes
| free = Yes
}}
The '''Apple Lossless Audio Codec''' ('''ALAC''', {{IPAc-en|ə|ˈ|l|æ|k}}), also known as '''Apple Lossless''', or '''Apple Lossless Encoder''' ('''ALE'''), is an [[audio coding format]], and its reference [[audio codec]] implementation, developed by [[Apple Inc.|Apple]] for [[lossless data compression]] of digital [[music]]. After initially keeping it [[proprietary format|proprietary]] from its inception in 2004, in late 2011 Apple made the codec available [[open-source software|open source]] and [[royalty-free]]. Traditionally, Apple has referred to the codec as ''Apple Lossless'', though more recently, c.a. 2017, it has begun to use the abbreviated term ''ALAC'' when referring to the codec.<ref name="ALAC-term-1">{{cite web |date=May 8, 2017 |title=Subscribe to iTunes Match |url=https://support.apple.com/en-us/HT204146 |access-date=May 31, 2017 |publisher=Apple Inc |quote=If you have songs encoded in ALAC, WAV, or AIFF formats, we create an AAC 256&nbsp;Kbps version and upload it to iCloud so that it can be played on all of your other devices. |archive-date=January 9, 2024 |archive-url=https://web.archive.org/web/20240109220131/https://support.apple.com/en-us/HT204146 |url-status=live }}</ref><ref name="ALAC-term-2">{{cite web |date=May 12, 2017 |title=Access your music collection on all of your devices with Apple Music |url=https://support.apple.com/en-us/HT205919 |access-date=May 31, 2017 |publisher=Apple Inc |quote=We create AAC 256Kbps versions of songs that are encoded in ALAC, WAV, or AIFF formats and add the AAC version to iCloud Music Library. |archive-date=August 2, 2019 |archive-url=https://web.archive.org/web/20190802181932/https://support.apple.com/en-us/HT205919 |url-status=live }}</ref>

ALAC data is frequently stored within an [[MPEG-4 Part 14|MP4]] [[Container format (digital)|container]] with the [[filename extension]] ''[[.m4a]]''. This extension is also used by Apple for [[Advanced Audio Coding|AAC]] (which is a [[Lossy compression|lossy]] format) in an MP4 container (same container, different audio encoding). ALAC can also be used by the [[Core Audio Format|.CAF]] file type container, though this is much less common.

==Codec==
ALAC supports up to 8 channels of audio at 16, 20, 24 and 32 bit depth with a maximum sample rate of 384&nbsp;kHz.

ALAC also does not use any [[digital rights management|DRM]] scheme;{{dubious|Apple Lossless with Apple Music and DRM|date=February 2022}} but by the nature of the MP4 [[container format (digital)|container]], it is feasible that DRM could be applied to ALAC much in the same way it is applied to files in other QuickTime containers.

According to Apple, audio files compressed with its lossless codec will use up "about half the storage space" that the uncompressed data would require. Testers using a selection of music have found that compressed files are about 40% to 60% the size of the originals depending on the kind of music, which is similar to other lossless formats.<ref name="ALAC-space1">{{cite web|url=http://wiki.hydrogenaud.io/index.php?title=Lossless_comparison#Comparison_Table|title=Lossless comparison - HydrogenAudio Knowledgebase|publisher=HydrogenAudio|date=July 27, 2011|access-date=June 27, 2012|archive-date=May 13, 2021|archive-url=https://web.archive.org/web/20210513212036/http://wiki.hydrogenaud.io/index.php?title=Lossless_comparison#Comparison_Table|url-status=live}}</ref><ref name="ALAC-space2">{{cite web|url=http://www.mcelhearn.com/an-overview-of-apple-lossless-compression-results/|title=An Overview of Apple Lossless Compression Results|publisher=Kirkville|first=Kirk|last=McElhearn|date=November 5, 2011|access-date=June 27, 2012|archive-date=January 9, 2017|archive-url=https://web.archive.org/web/20170109104752/http://www.mcelhearn.com/an-overview-of-apple-lossless-compression-results/|url-status=live}}</ref>

ALAC has been measured to require around four times as much CPU power to decode than [[FLAC]] does,<ref name="Rockbox-comparison">{{cite web|url=http://www.rockbox.org/wiki/CodecPerformanceComparison|title=CodecPerformanceComparison|publisher=RockBox|date=July 28, 2013|access-date=November 29, 2014|archive-date=May 28, 2012|archive-url=https://web.archive.org/web/20120528090734/http://www.rockbox.org/wiki/CodecPerformanceComparison|url-status=live}}</ref> with implications for battery life on limited-power devices. Still, the format has been recommended for older [[iPod]] devices based on claims of lower power usage.<ref>{{cite book|url=http://my.safaribooksonline.com/book/audio/30000lti00201/internet-delivery-formats/ch12lev1sec3|title=The Mastering Engineer's Handbook: The Audio Mastering Handbook, Second Edition|at=Chapter 12. Internet Delivery Formats &gt; Lossless Codecs|isbn=978-1-59863-449-5|first=Bobby|last=Owsinski|publisher=Thomson Course Technology PTR|date=December 26, 2007|access-date=January 15, 2012|archive-date=September 8, 2011|archive-url=https://web.archive.org/web/20110908014656/http://my.safaribooksonline.com/book/audio/30000lti00201/internet-delivery-formats/ch12lev1sec3|url-status=dead}}</ref>

Partly because of the use of an MP4 container, ALAC does not contain integrated error checking.<ref>{{cite web|url=http://www.hydrogenaud.io/forums/index.php?s=&showtopic=33226&view=findpost&p=862031|title=Which is the best lossless codec? – Hydrogenaudio Forums|publisher=Hydrogenaudio|date=April 1, 2014|access-date=June 30, 2014}}</ref>

ALAC is not a variant of [[Advanced Audio Coding|AAC]] (which is a [[Lossy compression|lossy]] format), but rather an unrelated lossless format that uses [[linear prediction]] (similar to other lossless codecs).

==History==
The [[data compression]] software for encoding into ALAC files, Apple Lossless Encoder, was introduced into the Mac OS X [[Core Audio]] framework on April 28, 2004, together with the [[QuickTime]] 6.5.1 update, thus making it available in [[iTunes]] since version 4.5 and above, and its replacement, the Music application.<ref name="MW info 1">{{Cite web|title=QuickTime 6.5.1 adds Lossless Encoder, improves AAC|url=http://www.macworld.com/article/1031552/quicktime.html|website=[[Macworld]]|access-date=2016-01-24|date=2004-04-28|archive-date=2020-10-01|archive-url=https://web.archive.org/web/20201001051908/https://www.macworld.com/article/1031552/quicktime.html|url-status=live}}</ref> The codec is also used in the [[AirPort]] and [[AirPlay]] implementation.

David Hammerton and [[Serafina Brocious]] analyzed and [[Reverse engineering|reverse engineered]] the codec without any documents on the format. On March 5, 2005, Hammerton published a simple [[Open-source software|open source]] decoder written in the [[C (programming language)|C programming language]] on the basis of the work.<ref name="ALAC-reverse">{{cite web|year=2004|title=ALAC|url=http://craz.net/programs/itunes/alac.html|url-status=dead|archive-url=https://web.archive.org/web/20120620124229/http://craz.net/programs/itunes/alac.html|archive-date=June 20, 2012|access-date=June 27, 2012|publisher=Crazney.net}}</ref>

The Apple Lossless Encoder (and decoder) were released as open source software under the [[Apache License]] version 2.0 on October 27, 2011.<ref name="Apache-license">{{cite web|url=http://alac.macosforge.org/|title=Apple Lossless Audio Codec|publisher=MacOS Forge|date=October 27, 2011|access-date=October 29, 2011|archive-date=June 18, 2016|archive-url=https://web.archive.org/web/20160618193112/http://alac.macosforge.org/|url-status=live}}</ref><ref name="Apache-ars">{{cite web|last=Foresman|first=Chris|title=After seven years, Apple open sources its Apple Lossless Audio Codec|url=https://arstechnica.com/apple/news/2011/10/after-seven-years-apple-open-sources-its-apple-lossless-audio-codec.ars|publisher=Ars Technica|date=October 28, 2011|access-date=October 29, 2011|archive-date=October 29, 2011|archive-url=https://web.archive.org/web/20111029123807/http://arstechnica.com/apple/news/2011/10/after-seven-years-apple-open-sources-its-apple-lossless-audio-codec.ars|url-status=live}}</ref><ref name="Apache-3">{{cite web|url=http://h-online.com/-1368212|archive-url=https://web.archive.org/web/20120515214941/http://www.h-online.com/open/news/item/Apple-open-sources-its-ALAC-lossless-audio-codec-1368212.html|archive-date=15 May 2012|title=Apple open sources its ALAC lossless audio codec|first=Chris|last=von Eitzen|publisher=[[The H]]|date=October 28, 2011|access-date=October 29, 2011}}</ref>

On May 17, 2021, Apple announced that they would begin offering lossless audio in [[Apple Music]] in June 2021, with all lossless music being encoded using ALAC.<ref>{{cite web |title=Apple Music announces Spatial Audio and Lossless Audio |url=https://www.apple.com/newsroom/2021/05/apple-music-announces-spatial-audio-and-lossless-audio/ |website=Apple Newsroom |quote=Apple Music will also make its catalog of more than 75 million songs available in Lossless Audio. Apple uses ALAC (Apple Lossless Audio Codec) to preserve every single bit of the original audio file. This means Apple Music subscribers will be able to hear the exact same thing that the artists created in the studio. |access-date=2021-05-17 |archive-date=2021-05-25 |archive-url=https://web.archive.org/web/20210525190429/https://www.apple.com/newsroom/2021/05/apple-music-announces-spatial-audio-and-lossless-audio/ |url-status=live }}</ref>

==Software==
All current iOS devices can play ALAC encoded files.

However, in the [[IOS 9|iOS 9.3.6 (13G37)]] update, which was released on July 22, 2019, after [[IOS 9|iOS 9.3.5 (13G36)]] on August 25, 2016,{{Relevance inline|date=September 2025}} as the last update for the [[IPhone 4s|iPhone 4S]] and aimed at fixing security issues, etc., there was still a bug with the ALAC codec in [[Music (app)|Music]] app.
This issue involved songs with the ALAC codec being synced internally to the phone by [[iTunes]] (known as [[Music (app)|Apple Music]] as of June 3, 2019), and when playing that song/album, the album cover from another album (in a non-ALAC format) would be displayed.{{Citation needed|date=September 2025}}

The open source library [[libavcodec]] incorporates both a decoder and an encoder for the ALAC format, which means that [[:Category:Software that uses FFmpeg|media players based on that library]] (including [[VLC media player]] and [[MPlayer]], as well as many media center applications for [[home theater PC|home theater computer]]s, such as [[Plex (software)|Plex]], [[Kodi (software)|Kodi]], and [[Boxee]]) are able to play ALAC files.

The introduction of the [[BlackBerry 10|BlackBerry OS 10]] in 2013 made it possible to play the ALAC Audio Codec.
Earlier, the [[BlackBerry OS|BlackBerry OS 7]] operating system in 2011 had enabled the playback of the [[FLAC]] on [[BlackBerry|BlackBerry phones.]]

As of 2015, [[Windows 10]] includes support for ALAC encoding and decoding, thereby enabling other media players to use it, e.g. [[Windows Media Player]] when ripping CDs or the [[Spotify]] desktop client for playback of local .m4a files.
The library was subsequently optimized for ARM processors and included in [[Rockbox]].{{Clarify|reason=which library|date=July 2021}}

[[Foobar2000]] will play ALAC files as will [[JRiver Media Center]] and BitPerfect.

Lossless music via ALAC was added to [[Apple Music]] in June 2021, at no additional cost for all subscribers. The maximum fidelity for lossless music on Apple Music is 24-bit at 192&nbsp;kHz.<ref>{{cite web |title=Apple Music announces Spatial Audio and Lossless Audio |url=https://www.apple.com/newsroom/2021/05/apple-music-announces-spatial-audio-and-lossless-audio/ |website=Apple Newsroom |access-date=17 May 2021 |archive-date=25 May 2021 |archive-url=https://web.archive.org/web/20210525190429/https://www.apple.com/newsroom/2021/05/apple-music-announces-spatial-audio-and-lossless-audio/ |url-status=live }}</ref>

==See also==
{{Portal|Free and open-source software}}
*[[Audio Interchange File Format]] (AIFF)
*[[Comparison of audio coding formats]]
*[[Free Lossless Audio Codec]] (FLAC)
*[[Monkey's Audio]]
*TTA
*[[WavPack]]
*[[Windows Media Audio 9 Lossless]]

==References==
{{reflist|colwidth=50em}}

==External links==
*[http://alac.macosforge.org ALAC Project] at MacOSForge
*[http://alac.macosforge.org/trac/browser/trunk/ReadMe.txt ALAC] technical features at MacOSForge
*[https://web.archive.org/web/20110329002415/http://www.apple.com/itunes/features/#importing ALAC] importing at [[Apple Inc.|Apple]]
*[https://kirkville.com/an-overview-of-apple-lossless-compression-results ALAC compression rates for different types of music] article by Kirk McElhern

{{Compression formats}}
{{Compression Software Implementations}}
{{Apple}}

[[Category:Free audio codecs]]
[[Category:Lossless audio codecs]]
[[Category:Formerly proprietary software]]
[[Category:IPod]]
[[Category:ITunes]]
[[Category:QuickTime|Lossless]]
[[Category:Open file formats]]
[[Category:Software using the Apache license]]