Advanced Audio Coding
| Filename extension |
|
|---|---|
| Internet media type | audio/aac, audio/aacp, audio/3gpp, audio/3gpp2, audio/mp4, audio/mp4a-latm, audio/mpeg4-generic |
| Developed by | Bell Labs, Fraunhofer Institute, Dolby Labs, Sony and Nokia |
| Initial release | 1997 |
| Type of format | Audio compression format, Lossy compression |
| Contained by | MPEG-4 Part 14, 3GP and 3G2, ISO base media file format and Audio Data Interchange Format (ADIF) |
| Standard |
ISO/IEC 13818-7, ISO/IEC 14496-3 |
MPEG/3GPP container
Apple container
Raw stream
Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates.
AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4 specifications. Part of the AAC known as High Efficiency Advanced Audio Coding (HE-AAC) which is part of MPEG-4 Audio is also adopted into digital radio standards like DAB+ and Digital Radio Mondiale, as well as mobile television standards DVB-H and ATSC-M/H.
AAC supports inclusion of 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 16 low frequency effects (LFE, limited to 120 Hz) channels, up to 16 "coupling" or dialog channels, and up to 16 data streams. The quality for stereo is satisfactory to modest requirements at 96 kbit/s in joint stereo mode; however, hi-fi transparency demands data rates of at least 128 kbit/s (VBR). Tests of MPEG-4 audio have shown that AAC meets the requirements referred to as "transparent" for the ITU at 128 kbit/s for stereo, and 320 kbit/s for 5.1 audio.
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