|Filename extensions||MPEG/3GPP Container
ADTS Stream - NOT raw - Contains Headers
|Internet media type|
|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)|
High-Efficiency Advanced Audio Coding (HE-AAC) is an audio coding format for lossy data compression of digital audio defined as an MPEG-4 Audio profile in ISO/IEC 14496-3. It is an extension of Low Complexity AAC (AAC LC) optimized for low-bitrate applications such as streaming audio. HE-AAC version 1 profile (HE-AAC v1) uses spectral band replication (SBR) to enhance the compression efficiency in the frequency domain. HE-AAC version 2 profile (HE-AAC v2) couples SBR with Parametric Stereo (PS) to enhance the compression efficiency of stereo signals. It is a standardized and improved version of the AACplus codec.
The progenitor of HE-AAC was developed by Coding Technologies under the trade name CT-aacPlus. CT-aacPlus combined MPEG-2 AAC LC with the Coding Technologies invented spectral band replication (SBR). CT-aacPlus is the codec used by XM Radio for their satellite radio service. Subsequently, Coding Technologies submitted their SBR to MPEG as a basis of HE-AAC.
HE-AAC version 1 was standardized as a profile of MPEG-4 Audio in 2003 by MPEG and published as part of MPEG-4 in document ISO/IEC 14496-3:2001/Amd 1:2003. The HE-AAC version 2 profile was standardized in 2006 as ISO/IEC 14496-3:2005/Amd 2:2006. A parametric stereo coding tool used in HE-AAC v2 was standardized in 2004 by MPEG and published in document ISO/IEC 14496-3:2001/Amd 2:2004.
HE-AAC version 2 was also standardized under the name Enhanced aacPlus by 3GPP for 3G UMTS multimedia services in September 2004 (3GPP TS 26.401). It is based on the AAC LC, SBR and Parametric Stereo coding tools defined in the MPEG-4 Audio standard (and it refers to ISO/IEC 14496-3:2001/Amd.1:2003 - Bandwidth Extension, ISO/IEC 14496-3:2001/Amd.2:2004 - Parametric Coding for High Quality Audio, ISO/IEC 14496-3:2001 and ISO/IEC 14496-3:2001/Amd.1:2003/DCOR1). In addition it includes further tools such as error concealment, spline resampler, and stereo-to-mono downmix. It was also published by ETSI as TS 126 401 V6.1.0 in December 2004.
Prior to the standardization of HE AAC v2 by MPEG, Coding Technologies submitted the combination of HE-AAC v1 coupled with Parametric Stereo under the name Enhanced AAC+. As a result, aacPlus v2 and eAAC+ are now common trade names that refer to HE-AAC v2. AAC+ and aacPlus are common trade names that refer to HE-AAC v1.
Testing indicates that material decoded from 64 kbit/s HE-AAC does not yet have similar audio quality to material decoded from MP3 at 128 kbit/s using high quality encoders. The test, taking bitrate distribution and RMSD into account, is a tie between mp3PRO, HE AAC and Ogg Vorbis.
Further controlled testing by 3GPP during their revision 6 specification process indicates that HE-AAC and its derivative MPEG-4 HE-AAC v2 provide "Good" audio quality for music at low bit rates (e.g., 24 kbit/s).
A 2011 Public Listening Test compared the two best-rated HE AAC encoders at that time to Opus and Ogg Vorbis, indicated statistically significant superiority at 64 kbit/s for Opus over all other contenders, and second ranked Apple HE AAC statistically superior to both Ogg Vorbis and Nero HE AAC which were tied for third place.
MPEG-2 and MPEG-4 AAC LC decoders without SBR support will decode the AAC LC part of the audio, resulting in audio output with only half the sampling frequency, thereby reducing the audio bandwidth. This usually results in the high-end, or treble, portion of the audio signal missing from the audio product.
Orban Opticodec-PC Streaming and File Encoders were the first commercially available encoders supporting AAC-LC/HE-AAC back in 2003. They are now deprecated and replaced with StreamS Encoders from StreamS/Modulation Index with many more features, including support xHE-AAC/Unified Speech and Audio Coding. They are now in use at some of the largest content providers, and are considered to be the standard of the industry for live encoding.
Sony supports HE-AAC encoding since SonicStage version 4.
XLD, an OS X audio encoding program, offers encoding from any of its supported formats to HE-AAC.
Nokia PC Suite may encode audiofiles to eAAC+ format before transmitting them to mobile phone.
HE-AAC is supported in the open source FAAD/FAAD2 decoding library and all players incorporating it, such as VLC media player, Winamp, foobar2000, Audacious Media Player, SonicStage and Die Plattenkiste.
The Nero AAC Codec supports decoding HE and HEv2 AAC.
iTunes 9.2 and iOS 4 include full decoding of HE-AAC v2 parametric stereo streams.
Dolby released Dolby Pulse decoders and encoders in September 2008. HE-AAC v2 is the core of Dolby Pulse so files and streams encoded in Dolby Pulse will playback on AAC, HE-AAC v1 and v2 decoders. Conversely files and streams encoded in AAC, HE-AAC v1 or v2 will playback on Dolby Pulse decoders.
Dolby Pulse provides the following additional capabilities beyond HE-AAC v2:
Dolby has additionally released a PC decoder as an SDK suitable for integration into PC applications requiring Dolby Pulse, HE-AAC or AAC playback capabilities.
|AIMP||Windows||A Winamp-like alternative music player.|
|Adobe Flash Player||Windows, OS X, Chrome OS, Linux||Browser plug-in. Supports AAC+ from any RTMP source.|
|Amarok (software)||Windows, Linux||Open-source music player.|
|Audacious Media Player||Windows, Linux||Open-source music player.|
|Deadbeef||Linux, Android||Open-source music player.|
|Die Plattenkiste||Windows||Freeware internet radio application (in German).|
|foobar2000||Windows||Freeware music player.|
|FStream||OS X, iOS||Internet radio application.|
|GuguRadio||iOS||Internet radio application.|
|Internet Radio Player||Android||Internet radio player.|
|Internet Radio Box||iOS||Internet radio application.|
|iTunes||Windows, OS X||Freeware music player. Pre-installed on Mac computers.|
|JetAudio||Windows, Android||Shareware media player.|
|MediaHuman Audio Converter||Windows, OS X||Freeware audio converter.|
(Supports conversion of MP3, AAC, AIFF, WAV etc.)
|MPlayer||Windows, OS X and Linux||Open-source media player.|
|Mpv (media player)||Windows, OS X and Linux||Open-source media player.|
|QuickTime X||OS X||Media player pre-installed on OS X Snow Leopard or later.|
|RealPlayer||Windows, OS X, Linux, Android||Freemium media player. |
(HE-AAC v2 will only play in mono)
|Rhythmbox||Linux||Open-source music player.|
|Snowtape||OS X||Shareware internet radio application.|
|streamWriter||Windows||Open-source internet radio application.|
|StreamS HiFi Radio||iOS||Paidware internet radio player.|
|Tunein radio||iOS, Android, Windows Phone, Blackberry||Internet radio player.|
|VLC media player||Windows, OS X, Linux, iOS, Android||Open-source media player.|
|Winamp||Windows, OS X, Android||Freeware media player.|
|XiiaLive||Android, iOS||Internet radio player.|
|Kodi||Windows, Linux, OS X, Android||Open-source media player.|
|Media Player Classic||Windows||Open-source media player|
HE-AAC is marketed under the trademark aacPlus by Coding Technologies and under the trademark Nero Digital by Nero AG. Sony Ericsson, Nokia and Samsung use AAC+ to label support for HE AAC v1 and eAAC+ to label support for HE-AAC v2 on their phones. Motorola uses AAC+ to indicate HE AAC v1 and "AAC+ Enhanced" to indicate HE AAC v2.
Patent licenses are required for end-product companies that make hardware or software products that include HE AAC encoders and/or decoders. Unlike the MP3 format before April 23, 2017, content owners are not required to pay license fees to distribute content in HE AAC.
HE-AAC profile was first standardized in ISO/IEC 14496-3:2001/Amd 1:2003. HE-AAC v2 profile (HE-AAC with Parametric Stereo) was first specified in ISO/IEC 14496-3:2005/Amd 2:2006. The Parametric Stereo coding tool used by HE-AAC v2 was standardized in 2004 and published as ISO/IEC 14496-3:2001/Amd 2:2004.
The current version of the MPEG-4 Audio (including HE-AAC standards) is published in ISO/IEC 14496-3:2009.
Enhanced aacPlus is required audio compression format in 3GPP technical specifications for 3G UMTS multimedia services and should be supported in IP Multimedia Subsystem (IMS), Multimedia Messaging Service (MMS), Multimedia Broadcast/Multicast Service (MBMS) and Transparent end-to-end Packet-switched Streaming Service (PSS). HE-AAC version 2 was standardized under the name Enhanced aacPlus by 3GPP for 3G UMTS multimedia services in September 2004 (3GPP TS 26.401).
HE-AAC and HE-AAC v2 audio coding for DVB applications is standardized by TS 101 154. AacPlus v2 by Coding Technologies is also standardized by the ETSI as TS 102 005 for Satellite services to Handheld devices (DVB-SH) below 3 GHz.
In December 2007, Brazil started broadcasting terrestrial DTV standard called International ISDB-Tb that implements video coding H.264 with audio AAC LC on main program (single or multi) and video H.264 with audio HE-AACv2 in the 1Seg mobile sub-program.
The following is the summary of the different versions of HE-AAC:
|Version||Common trade names||Codec feature||Standards|
|HE-AAC v1||aacPlus v1, eAAC, AAC+, CT-aacPlus||AAC LC + SBR||ISO/IEC 14496-3:2001/Amd 1:2003|
|HE-AAC v2||aacPlus v2, eAAC+, AAC++, Enhanced AAC+||AAC LC + SBR + PS||ISO/IEC 14496-3:2005/Amd 2:2006|
|xHE-AAC||aacPlus v2, eAAC+, AAC++, Enhanced AAC+||AAC LC + SBR + PS + USAC||ISO/IEC 23003-3:2012/Amd 2:2012|