ALAC

ALAC is Apple's lossless audio codec, introduced in 2004 and open-sourced under the Apache License in 2011, compressing PCM audio to roughly half size with no quality loss inside an M4A container.

Extension

.m4a

Full name

Apple Lossless Audio Codec

Introduced

2004

Vendor

Apple

What is inside the container

ALAC audio is packaged inside the same MP4-based container as AAC, and both commonly use the .m4a extension — so a DAM cannot distinguish a lossless ALAC master from a lossy AAC file by extension alone and must read the codec identifier inside the container. Metadata support comes from the surrounding MP4 atom structure (the same iTunes-style tagging used for AAC), covering title, artist, album art and similar fields.

How to open it

macOS / iOS Music.app and QuickTime Player play ALAC natively

Windows iTunes for Windows or VLC Media Player

Cross-platform FFmpeg for command-line decoding and conversion; foobar2000 with an ALAC plugin

DAM workflow Inspect the MP4 codec atom, not the .m4a extension, to confirm ALAC vs AAC before archiving

For archives

ALAC is a legitimate lossless archival option, functionally comparable to FLAC, and became fully royalty-free once Apple open-sourced its encoder/decoder in 2011. For DAMs operating primarily in an Apple-centric ecosystem (Apple Music delivery, Logic Pro production), ALAC is a reasonable native choice for lossless masters; for cross-platform libraries, FLAC generally has broader tooling support outside Apple software, so many DAMs standardize on FLAC even when source files arrive as ALAC.

Apple introduced Apple Lossless in 2004 as a proprietary lossless codec for iTunes and iPod, at a time when the only well-established alternative for lossless compression was the community-driven FLAC. For its first several years, ALAC’s encoder and decoder were closed source, which limited its adoption outside Apple’s own software. That changed on October 27, 2011, when Apple released the ALAC source code as open source under the Apache License 2.0, making it free of both cost and licensing restriction for any developer to implement.

2004 — Apple introduces Apple Lossless, closed source, tied to iTunes and iPod
October 27, 2011 — Apple open-sources the encoder/decoder under the Apache License 2.0
Post-2011 — FFmpeg, VLC and eventually Windows 10/11 add native ALAC support
Today — a royalty-free, increasingly cross-platform lossless option alongside FLAC

Since that 2011 release, ALAC has gained support well beyond Apple’s own platforms — Windows 10/11 support it natively, and open tools like FFmpeg and VLC decode it freely. Its compression approach is broadly similar to FLAC’s, reducing PCM audio to roughly half its uncompressed size with zero quality loss, though the two formats remain incompatible containers requiring conversion between them.

The recurring practical issue for a DAM is that ALAC shares the .m4a file extension with lossy AAC, since both live inside the same MP4-family container. A media library ingested from an Apple-centric production pipeline may contain a mix of lossless ALAC masters and lossy AAC previews all labeled .m4a, so any automated cataloging step needs to read the actual codec identifier inside the file rather than infer quality from the extension.

Frequently asked

Does ALAC require a license to encode or decode in DAM software?

No — Apple open-sourced the ALAC encoder and decoder under the Apache License 2.0 in October 2011, making it free of licensing restrictions and royalty obligations for any developer or DAM vendor to implement.

How can a DAM tell an ALAC file apart from an AAC file when both use .m4a?

By reading the codec identifier inside the MP4 container's audio track description, not the file extension — both codecs commonly share .m4a, so extension-based sorting will misclassify lossless ALAC masters as lossy AAC files or vice versa.

Is ALAC or FLAC the better choice for a DAM's lossless archival tier?

Both offer equivalent lossless fidelity and similar compression ratios. FLAC generally has broader tooling and playback support outside Apple's ecosystem, so cross-platform DAM deployments often standardize on FLAC, while Apple-centric production pipelines may keep ALAC as the native lossless format.

Can ALAC files be converted to FLAC without any quality loss?

Yes — since both are lossless codecs, decoding ALAC to raw PCM and re-encoding to FLAC preserves the audio exactly, with no generational quality loss, unlike converting between two lossy formats.

Does ALAC support the same metadata fields as AAC?

Yes — both use the same MP4 atom-based metadata structure, so a DAM's parser for AAC/M4A tags (title, artist, cover art) works identically for ALAC files, aside from needing to separately confirm the audio codec itself.

Was ALAC always open source, or only after a certain date?

Only after October 27, 2011. Before that, ALAC's encoder and decoder were proprietary and closed source, which is part of why FLAC, open from its 2001 debut, became the more widely adopted lossless format outside Apple's own ecosystem during that period.

Does Windows support ALAC playback without third-party software?

Windows 10 and 11 support ALAC natively at the OS media-framework level, and it can also be played through iTunes for Windows or VLC Media Player, so a DAM serving ALAC files to Windows clients has multiple reliable playback paths.

Is ALAC compression as efficient as MP3 or AAC for reducing file size?

No, and it isn't meant to be — as a lossless codec ALAC only reduces file size by roughly half compared to uncompressed PCM, while lossy codecs like MP3 or AAC can shrink files by 80–90% at the cost of permanently discarding audio detail.

Sources

Apple introduced Apple Lossless (ALAC) in 2004 and released its encoder and decoder as open-source software under the Apache License 2.0 on October 27, 2011. checked 2026-08-07 — 9to5Mac — Apple open sources their Lossless Audio Codec (ALAC)