Advanced Audio Coding - Wikipedia, the free encyclopedia


** Advanced Audio Coding **

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This article is about an audio compression and encoding scheme. For the
NCAA Division I conference, see American Athletic Conference. For other
uses, see AAC.

Advanced Audio Codings
Filename extension .m4a, .m4b, .m4p, .m4v, .m4r, .3gp, .mp4, .aac
Internet media type audio/aac, audio/aacp, audio/3gpp, audio/3gpp2,
audio/mp4, audio/MP4A-LATM, audio/mpeg4-generic
Initial release 1997 (1997)^[1]
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(s) ISO/IEC 13818-7,
ISO/IEC 14496-3

*Advanced Audio Coding* (*AAC*) is a standardized, lossy compression and
encoding scheme for digital audio. Designed to be the successor of the MP3
format, AAC generally achieves better sound quality than MP3 at similar bit

AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4
specifications.^[3]^[4] 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). The MPEG-2 audio tests showed 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.

AAC is also the default or standard audio format for YouTube


what is aac format

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