The Apple Lossless Audio Codec (ALAC), 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. for lossless data compression of digital music. After initially keeping it proprietary from its inception in 2004, in late 2011 Apple made the codec available

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

and

royalty-free Royalty-free (RF) material subject to copyright or other intellectual property rights may be used without the need to pay royalties or license fees for each use, per each copy or volume sold or some time period of use or sales. Computer standard ...

. Traditionally, Apple has referred to the codec as ''Apple Lossless'', though more recently it has begun to use the abbreviated term ''ALAC'' when referring to the codec.

Codec

ALAC supports up to 8 channels of audio at 16, 20, 24 and 32 bit depth with a maximum sample rate of 384 kHz. ALAC data is frequently stored within an MP4 container with the filename extension ''

.m4a MPEG-4 Part 14 or MP4 is a digital multimedia container format most commonly used to store video and audio, but it can also be used to store other data such as subtitles and still images. Like most modern container formats, it allows streami ...

''. This extension is also used by Apple for lossy AAC audio data in an MP4 container (same container, different audio encoding). The codec can also be used by the .CAF file type container, though this is much less common. ALAC is not a variant of

AAC AAC may refer to: Aviation * Advanced Aircraft, a company from Carlsbad, California * Alaskan Air Command, a radar network * American Aeronautical Corporation, a company from Port Washington, New York * American Aviation, a company from Cleveland, ...

(which is a lossy format), but rather an unrelated lossless format that uses linear prediction (similar to other lossless codecs). ALAC also does not use any DRM scheme; but by the nature of the MP4 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. ALAC has been measured to require around four times as much CPU power to decode than FLAC does, with implications for battery life on limited-power devices. Still the format has been recommended for older

iPod The iPod is a discontinued series of portable media players and multi-purpose mobile devices designed and marketed by Apple Inc. The first version was released on October 23, 2001, about months after the Macintosh version of iTunes ...

devices based on claims of lower power usage. Partly because of the use of an MP4 container, ALAC does not contain integrated error checking.

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 QuickTime is an extensible multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. Created in 1991, the latest Mac version, QuickTime X, is avai ...

6.5.1 update, thus making it available in

iTunes iTunes () is a software program that acts as a media player, media library, mobile device management utility, and the client app for the iTunes Store. Developed by Apple Inc., it is used to purchase, play, download, and organize digital mul ...

since version 4.5 and above, and its replacement, the Music application. The codec is also used in the AirPort and AirPlay implementation. David Hammerton and Cody Brocious analyzed and reverse engineered the codec without any documents on the format. On March 5, 2005, Hammerton published a simple

decoder written in the

C programming language ''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as ...

on the basis of the work. The Apple Lossless Encoder (and decoder) were released as open source software under the Apache License version 2.0 on October 27, 2011. 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.

Apple support for lossless formats

Other lossless codecs, such as

FLAC FLAC (; Free Lossless Audio Codec) is an audio coding format for lossless compression of digital audio, developed by the Xiph.Org Foundation, and is also the name of the free software project producing the FLAC tools, the reference software p ...

and Shorten, are not natively supported by Apple's

nor the later Music app (either the macOS or Windows versions) or by iOS devices running iOS 10 or below. In order to be played through the iTunes and Music app on iOS, audio files using these lossless codecs may be converted via various third-party tools into ALAC-encoded files with no change in fidelity. Third-party applications are available from the App Store to play such files without converting them. Devices running

iOS 11 iOS 11 is the iOS version history, eleventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 10. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers C ...

or above do support FLAC playback natively, through the

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application only. The method of importing the files to the Apple device varies between applications, including Files, as there is currently no official support for doing so.

Software

All current iOS devices can play ALAC encoded files. The open source library libavcodec incorporates both a decoder and an encoder for the ALAC format, which means that media players based on that library (including VLC media player and MPlayer, as well as many media center applications for home theater computers, such as Plex, XBMC, and Boxee) are able to play ALAC files. 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.

Foobar2000 foobar2000 (often abbreviated as fb2k or f2k) is a freeware audio player for Microsoft Windows, iOS and Android developed by Peter Pawłowski. It has a modular design, which provides user flexibility in configuration and customization. Stan ...

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 kHz.

References

External links