ALAC Format Guide

Available Conversions

Convert to ALAC

About ALAC Format

ALAC (Apple Lossless Audio Codec), also known as Apple Lossless, is a lossless audio compression codec developed by Apple Inc. Unlike lossy formats such as MP3 or AAC that permanently discard audio data to reduce file size, ALAC compresses audio without any loss of quality, preserving every bit of the original recording. ALAC files are stored in an M4A (MPEG-4 Audio) or CAF (Core Audio Format) container and typically achieve compression ratios of 40-60% compared to uncompressed audio. The format is natively supported across Apple's entire ecosystem, including iPhone, iPad, Mac, Apple TV, HomePod, and Apple Music. ALAC provides the same bit-perfect audio quality as FLAC but with seamless integration into iTunes and the Apple ecosystem, making it the preferred lossless format for Apple users who demand audiophile-grade audio quality.

History of ALAC

Apple developed ALAC and first introduced it in April 2004 as part of QuickTime 6.5.1 and iTunes 4.5. The codec was created to provide Apple users with a lossless audio option within the iTunes ecosystem, as the existing AAC codec was lossy by design. Initially, ALAC was a proprietary, closed-source format, which limited its adoption outside Apple's ecosystem despite its technical merits. In October 2011, Apple made a landmark decision by releasing the ALAC reference encoder and decoder as open-source software under the Apache License 2.0, hosted on the macOS Forge website. This open-source release enabled third-party developers, media players, and hardware manufacturers to implement ALAC support without licensing restrictions. VLC, foobar2000, and ffmpeg quickly added ALAC support following the open-source release. In 2021, Apple launched Apple Music Lossless, offering its entire music catalog in ALAC format at up to 24-bit/192 kHz resolution, bringing lossless audio to mainstream consumers at no additional cost. This move significantly boosted ALAC's prominence in the audio industry, as Apple Music's 100+ million subscribers gained access to lossless ALAC streams. Today, ALAC is one of the two dominant lossless audio formats alongside FLAC, with strong support across both Apple and non-Apple platforms.

Key Features and Uses

ALAC supports a wide range of audio specifications, including sample rates from 1 Hz to 384 kHz and bit depths of 16, 20, 24, and 32 bits. The codec supports mono through 8-channel audio (7.1 surround), though stereo is the most common configuration. ALAC uses linear prediction and adaptive Rice coding for its compression algorithm, achieving typical compression ratios of 40-60% depending on the source material. Unlike FLAC, ALAC stores its audio data within an MPEG-4 container, which provides native support for rich metadata including album artwork, lyrics, chapter markers, and extensive tagging through iTunes-compatible atoms. The M4A container also supports gapless playback natively, essential for live recordings and concept albums. ALAC encoding and decoding is highly efficient, requiring minimal CPU resources, which is important for battery-powered devices. Apple Music streams ALAC in two quality tiers: Lossless (up to 24-bit/48 kHz, using ALAC) and Hi-Res Lossless (up to 24-bit/192 kHz, also using ALAC), with the codec's efficient compression keeping bandwidth requirements reasonable for streaming applications.

Common Applications

ALAC is the native lossless audio format for Apple's entire product ecosystem. Apple Music uses ALAC for its lossless streaming tier, delivering over 100 million tracks in lossless quality. iTunes and the Apple Music app on Mac, iPhone, iPad, and Apple TV support ALAC playback and library management natively. Audio ripped from CDs using iTunes can be encoded directly to ALAC, preserving perfect quality for digital archival. Professional musicians and audio engineers working within the Apple ecosystem use ALAC for storing high-resolution masters and reference recordings. Logic Pro and GarageBand support ALAC import and export. ALAC is commonly used by audiophiles who maintain large music libraries on Apple devices, as it provides the best balance of lossless quality and Apple ecosystem integration. Since the open-source release, ALAC is also supported by non-Apple players including VLC, foobar2000, Winamp, and various Android music players. Network audio players and DACs from brands like Sonos, Bluesound, and Cambridge Audio support ALAC streaming. The format is also used for archiving vinyl records and analog tape transfers within Apple's ecosystem, ensuring bit-perfect preservation of digitized analog recordings.

Advantages and Disadvantages