AAC Format Guide

Available Conversions

About AAC Format

AAC (Advanced Audio Coding) is a lossy audio compression format designed as the successor to MP3, offering better sound quality at the same bitrate. Developed by a consortium including Dolby, Sony, and AT&T, AAC has become the default audio format for Apple's iTunes and iOS devices, YouTube, Nintendo gaming consoles, PlayStation, and numerous streaming services. The format provides efficient compression while maintaining high audio fidelity, making it ideal for digital music distribution, streaming, and mobile devices where storage and bandwidth are considerations.

History of AAC

AAC was developed in the mid-1990s by the MPEG (Moving Picture Experts Group) as part of the MPEG-2 standard, and later enhanced in MPEG-4. The format was standardized in 1997 as part of MPEG-2 Part 7, with significant improvements added in 1999 as MPEG-4 Part 3. The development team included companies like Fraunhofer IIS (the creators of MP3), Dolby Laboratories, Sony, AT&T, and Nokia. AAC was designed from the ground up to overcome the limitations of MP3 and to provide better audio quality at lower bitrates. Apple's adoption of AAC for iTunes and the iPod in 2003 significantly boosted the format's popularity. The format gained further traction when YouTube selected AAC as its standard audio codec in 2008. Today, AAC is supported by virtually all modern devices and is the de facto standard for mobile music, streaming services, and digital broadcasting.

Key Features and Uses

AAC offers several advantages over MP3, including improved compression efficiency (approximately 30% better at the same bitrate), support for more audio channels (up to 48), better handling of frequencies above 16 kHz, and more efficient encoding of stereo signals. The format supports variable bitrate (VBR) encoding, which optimizes quality by allocating more bits to complex passages and fewer to simple ones. AAC includes several profiles optimized for different uses: AAC-LC (Low Complexity) for general use, HE-AAC (High Efficiency) for low-bitrate streaming, and AAC-LD (Low Delay) for real-time communication. The format supports sample rates from 8 kHz to 96 kHz and bitrates from 8 kbps to 512 kbps per channel. AAC files can include metadata, album art, and lyrics. The format's DRM capabilities (FairPlay in Apple's ecosystem) allow for copy protection, though DRM-free AAC is now standard in most music stores.

Common Applications

AAC is the standard audio format for Apple's entire ecosystem: iTunes Store, Apple Music, iPhones, iPads, and iPods all use AAC as their primary audio format. The format is used extensively in streaming services including YouTube (all video audio), SoundCloud, Deezer, and many others. AAC is the default audio codec for digital television broadcasting (DVB), digital radio (DAB+), and ISDB systems in Japan and South America. Gaming consoles including Nintendo 3DS, Wii U, PlayStation 3, 4, and 5 use AAC for game audio and music. The format is popular in mobile apps, podcasts, audiobooks, and voice recordings due to its excellent quality-to-size ratio. Professional broadcasters use AAC for internet radio and digital transmissions. Android devices support AAC playback natively, and many Android phones use AAC for recording. The format's efficiency makes it ideal for streaming over mobile networks and for storing large music libraries on devices with limited storage.

Advantages and Disadvantages