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Technology

AAC LC Audio Codec: what it is, how it works and what it does

AAC LC is an MPEG-4 audio compression profile supporting multiple channel configurations and standard sampling rates, used in various multimedia containers.

Evidence-backed content 4 sources 15/09/2026
Encyclopedic article

Definition and Principles

AAC LC (Advanced Audio Coding Low Complexity) is an audio codec profile defined within the MPEG-4 standard. It functions by compressing audio signals to reduce storage and transmission size while maintaining acceptable perceptual quality. Technical documentation identifies this codec specifically as the MPEG-4 AAC Profile (AAC LC).

Technical Capabilities

The AAC LC codec is designed to handle a variety of audio configurations. Its main features include:

  • Channel Configurations: Support for mono, stereo, 5.0, and 5.1 content.
  • Sampling Rates: Compatibility with standard sampling rates ranging from 8 kHz to 48 kHz.

Containers and File Formats

The AAC LC codec can be packaged in various multimedia file containers. Compatibility varies by format:

  • 3GPP: Files with the .3gp extension.
  • MPEG-4: Files with the .mp4 and .m4a extensions.
  • ADTS (raw AAC): Files with the .aac extension. It is specified that the ADIF format is not supported.
  • MPEG-TS: Files with the .ts extension. These files are not seekable and are limited to decoding.
  • Matroska: Files with the .mkv extension. Limited to decoding.

Implementation and Data Framing

In systems such as Android, AAC support includes the use of ADTS framing and ID3 tags. The technical reference aac_adts_codec_support indicates that details on AAC and its variants are found in section 5.1.1 of the platform documentation.

Scope and Limitations

The scope of AAC LC focuses on digital audio playback in mobile devices and modern operating systems. Its limitations include the lack of support for the ADIF format within raw AAC files and the seekability restriction in MPEG-TS files, where only linear decoding is permitted.

Interpretation in Products

The presence of AAC LC in a product indicates that the device or software is capable of playing compressed audio files in industry-standard formats, such as MP4 and M4A, as well as real-time audio streams via ADTS. This ensures compatibility with a wide range of digital multimedia content.