High-Efficiency Advanced Audio Coding

High-Efficiency Advanced Audio Coding
Filename extensions	MPEG/3GPP container .m4a, .mp4, .3gp Apple container .m4a, .m4b, .m4p, .m4r, .m4v ADTS stream (not raw, contains headers) .aac
Internet media type	audio/aac audio/aacp audio/3gpp audio/3gpp2 audio/mp4
Developed by	ISO
Type of format	Audio compression format
Contained by	MPEG-4 Part 14, 3GP and 3G2, ISO base media file format, Audio Data Interchange Format (ADIF), Audio Data Transport Stream (ADTS)
Extended from	AAC
Standard	ISO/IEC 14496-3

Hierarchical structure of AAC profile, HE-AAC profile and HE-AAC v2 profile, and compatibility between them. The HE-AAC profile decoder is fully capable of decoding any AAC profile stream. Similarly, The HE-AAC v2 decoder can handle all HE-AAC profile streams as well as all AAC profile streams. Based on the MPEG-4 Part 3 technical specification. Evolution from MPEG-2 AAC-LC (Low Complexity) Profile and MPEG-4 AAC-LC Object Type to HE-AAC v2 Profile

High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio as part of the MPEG-4 standards. It is an extension of Low Complexity AAC (AAC-LC) optimized for low-bitrate applications such as streaming audio.

The usage profile HE-AAC v1 uses spectral band replication (SBR) to enhance the modified discrete cosine transform (MDCT) compression efficiency in the frequency domain. The usage profile HE-AAC v2 couples SBR with Parametric Stereo (PS) to further enhance the compression efficiency of stereo signals.

HE-AAC is defined as an MPEG-4 Audio profile in ISO/IEC 14496–3. HE-AAC is used in digital radio standards like HD Radio, DAB+ and Digital Radio Mondiale.