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Lossy audio pinch format

Advanced Audio Coding
Filename extension MPEG/3GPP container
  • .m4a, .mp4, .3gp

Apple tree container

  • .m4a, .m4b, .m4p, .m4r, .m4v

ADTS stream

  • .aac
Internet media blazon

audio/aac
audio/aacp
audio/3gpp
sound/3gpp2
audio/mp4
audio/mp4a-latm
audio/mpeg4-generic
Developed by Bong, Fraunhofer, Dolby, Sony, Nokia, LG Electronics, NEC, NTT Docomo, Panasonic[1]
Initial release 1997; 25 years ago  (1997) [2]
Latest release

ISO/IEC 14496-3:2019
December 2019; 2 years ago  (2019-12)

Type of format Lossy audio
Contained by MPEG-4 Role 14, 3GP and 3G2, ISO base media file format and Audio Data Interchange Format (ADIF)
Standard ISO/IEC 13818-vii,
ISO/IEC 14496-3
Open format? Yes
Free format? No[3]

Advanced Audio Coding (AAC) is an sound coding standard for lossy digital audio compression. Designed to exist the successor of the MP3 format, AAC by and large achieves higher audio quality than MP3 encoders at the same bit rate.[4]

AAC has been standardized by ISO and IEC equally role of the MPEG-2 and MPEG-4 specifications.[5] [half-dozen] Office of AAC, HE-AAC ("AAC+"), is part of MPEG-4 Audio and is adopted into digital radio standards DAB+ and Digital Radio Mondiale, and mobile television standards DVB-H and ATSC-M/H.

AAC supports inclusion of 48 full-bandwidth (up to 96 kHz) audio channels in ane stream plus sixteen low frequency furnishings (LFE, limited to 120 Hz) channels, up to xvi "coupling" or dialog channels, and upwards to 16 data streams. The quality for stereo is satisfactory to modest requirements at 96 kbit/s in joint stereo fashion; even so, hullo-fi transparency demands data rates of at least 128 kbit/s (VBR). Tests[ which? ] of MPEG-4 audio take shown that AAC meets the requirements referred to as "transparent" for the ITU at 128 kbit/s for stereo, and 320 kbit/s for v.i audio.[ citation needed ] AAC uses only a modified discrete cosine transform (MDCT) algorithm, giving it higher compression efficiency than MP3, which uses a hybrid coding algorithm that is role MDCT and part FFT.[4]

AAC is the default or standard audio format for iPhone, iPod, iPad, Nintendo DSi, Nintendo 3DS, YouTube Music, Apple Music (only used on web player, Google Home, Amazon Alexa, and Microsoft Windows app.), iTunes, DivX Plus Spider web Player, PlayStation 4 and diverse Nokia Series twoscore phones. It is supported on PlayStation Vita, Wii, Sony Walkman MP3, Android and BlackBerry. AAC is also supported past manufacturers of in-dash car audio systems.[ when? ] [ vague ] It is also one of the audio formats used on the Spotify spider web player.[7]

History [edit]

Groundwork [edit]

The discrete cosine transform (DCT), a type of transform coding for lossy compression, was proposed past Nasir Ahmed in 1972, and developed past Ahmed with T. Natarajan and K. R. Rao in 1973, publishing their results in 1974.[8] [ix] [ten] This led to the evolution of the modified discrete cosine transform (MDCT), proposed past J. P. Princen, A. Westward. Johnson and A. B. Bradley in 1987,[eleven] following before piece of work by Princen and Bradley in 1986.[12] The MP3 audio coding standard introduced in 1994 used a hybrid coding algorithm that is part MDCT and part FFT.[13] AAC uses a purely MDCT algorithm, giving it higher pinch efficiency than MP3.[4]

AAC was developed with the cooperation and contributions of companies including Bell Labs, Fraunhofer IIS, Dolby Laboratories, LG Electronics, NEC, NTT Docomo, Panasonic, Sony Corporation,[1] ETRI, JVC Kenwood, Philips, Microsoft, and NTT.[14] It was officially declared an international standard by the Moving Motion picture Experts Grouping in Apr 1997. Information technology is specified both every bit Part vii of the MPEG-2 standard, and Subpart iv in Part 3 of the MPEG-4 standard.[15]

Standardization [edit]

In 1997, AAC was first introduced equally MPEG-2 Part seven, formally known equally ISO/IEC 13818-7:1997. This part of MPEG-2 was a new part, since MPEG-two already included MPEG-2 Role 3, formally known as ISO/IEC 13818-iii: MPEG-2 BC (Backwards Uniform).[sixteen] [17] Therefore, MPEG-2 Office seven is too known as MPEG-2 NBC (Not-Astern Compatible), considering information technology is not compatible with the MPEG-1 sound formats (MP1, MP2 and MP3).[16] [18] [xix] [20]

MPEG-2 Part 7 defined 3 profiles: Low-Complexity profile (AAC-LC / LC-AAC), Main profile (AAC Main) and Scalable Sampling Charge per unit profile (AAC-SSR). AAC-LC contour consists of a base format very much similar AT&T'due south Perceptual Audio Coding (PAC) coding format,[21] [22] [23] with the addition of temporal noise shaping (TNS),[24] the Kaiser window (described below), a nonuniform quantizer, and a reworking of the bitstream format to handle up to 16 stereo channels, 16 mono channels, 16 low-frequency effect (LFE) channels and 16 commentary channels in one bitstream. The Main profile adds a set up of recursive predictors that are calculated on each tap of the filterbank. The SSR uses a 4-band PQMF filterbank, with iv shorter filterbanks post-obit, in order to permit for scalable sampling rates.

In 1999, MPEG-2 Office 7 was updated and included in the MPEG-iv family of standards and became known every bit MPEG-4 Part three, MPEG-4 Sound or ISO/IEC 14496-3:1999. This update included several improvements. One of these improvements was the add-on of Sound Object Types which are used to allow interoperability with a various range of other audio formats such equally TwinVQ, CELP, HVXC, Text-To-Speech Interface and MPEG-4 Structured Audio. Another notable add-on in this version of the AAC standard is Perceptual Racket Commutation (PNS). In that regard, the AAC profiles (AAC-LC, AAC Master and AAC-SSR profiles) are combined with perceptual racket exchange and are defined in the MPEG-4 audio standard equally Audio Object Types.[25] MPEG-4 Sound Object Types are combined in four MPEG-4 Sound profiles: Master (which includes most of the MPEG-iv Audio Object Types), Scalable (AAC LC, AAC LTP, CELP, HVXC, TwinVQ, Wavetable Synthesis, TTSI), Oral communication (CELP, HVXC, TTSI) and Low Rate Synthesis (Wavetable Synthesis, TTSI).[25] [26]

The reference software for MPEG-four Role three is specified in MPEG-four Part 5 and the conformance flake-streams are specified in MPEG-4 Part iv. MPEG-4 Audio remains backward-compatible with MPEG-2 Part seven.[27]

The MPEG-iv Audio Version 2 (ISO/IEC 14496-3:1999/Amd 1:2000) defined new audio object types: the low filibuster AAC (AAC-LD) object blazon, bit-sliced arithmetics coding (BSAC) object type, parametric sound coding using harmonic and individual line plus noise and error resilient (ER) versions of object types.[28] [29] [30] It also defined four new audio profiles: High Quality Audio Contour, Low Delay Audio Contour, Natural Audio Profile and Mobile Audio Internetworking Profile.[31]

The HE-AAC Profile (AAC LC with SBR) and AAC Contour (AAC LC) were first standardized in ISO/IEC 14496-3:2001/Amd ane:2003.[32] The HE-AAC v2 Profile (AAC LC with SBR and Parametric Stereo) was offset specified in ISO/IEC 14496-three:2005/Amd 2:2006.[33] [34] [35] The Parametric Stereo sound object type used in HE-AAC v2 was first defined in ISO/IEC 14496-3:2001/Amd 2:2004.[36] [37] [38]

The current version of the AAC standard is defined in ISO/IEC 14496-3:2009.[39]

AAC+ v2 is as well standardized by ETSI (European Telecommunication Standards Constitute) equally TS 102005.[36]

The MPEG-4 Role iii standard too contains other ways of compressing audio. These include lossless compression formats, synthetic audio and low bit-rate compression formats generally used for speech.

AAC'southward improvements over MP3 [edit]

Advanced Audio Coding is designed to exist the successor of the MPEG-one Sound Layer three, known as MP3 format, which was specified by ISO/IEC in 11172-3 (MPEG-i Audio) and 13818-3 (MPEG-2 Audio).

Blind tests in the late 1990s showed that AAC demonstrated greater sound quality and transparency than MP3 for files coded at the same scrap rate.[4]

Improvements include:

  • more sample rates (from 8 to 96 kHz) than MP3 (16 to 48 kHz);
  • up to 48 channels (MP3 supports up to ii channels in MPEG-1 mode and upwardly to 5.1 channels in MPEG-2 mode);
  • arbitrary bit rates and variable frame length. Standardized constant flake rate with flake reservoir;
  • higher efficiency and simpler filter banking concern. AAC uses a pure MDCT (modified discrete cosine transform), rather than MP3's hybrid coding (which was part MDCT and role FFT);
  • higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 or 960 samples, allowing more efficient coding than MP3's 576 sample blocks);
  • college coding accuracy for transient signals (AAC uses a blocksize of 128 or 120 samples, allowing more accurate coding than MP3's 192 sample blocks);
  • possibility to employ Kaiser-Bessel derived window office to eliminate spectral leakage at the expense of widening the main lobe;
  • much better handling of sound frequencies above 16 kHz;
  • more flexible articulation stereo (different methods can be used in different frequency ranges);
  • boosted modules (tools) added to increase compression efficiency: TNS, backwards prediction, perceptual noise substitution (PNS), etc. These modules can be combined to constitute different encoding profiles.

Overall, the AAC format allows developers more than flexibility to blueprint codecs than MP3 does, and corrects many of the design choices fabricated in the original MPEG-1 sound specification. This increased flexibility often leads to more than concurrent encoding strategies and, equally a event, to more efficient compression. This is specially true at very depression chip rates where the superior stereo coding, pure MDCT, and better transform window sizes go out MP3 unable to compete.

While the MP3 format has nearly-universal hardware and software support, primarily because MP3 was the format of choice during the crucial first few years of widespread music file-sharing/distribution over the internet, AAC is a strong contender due to some unwavering industry support.[twoscore]

Functionality [edit]

AAC is a wideband audio coding algorithm that exploits two primary coding strategies to dramatically reduce the amount of data needed to correspond high-quality digital sound:

  • Betoken components that are perceptually irrelevant are discarded.
  • Redundancies in the coded audio signal are eliminated.

The actual encoding procedure consists of the following steps:

  • The point is converted from time-domain to frequency-domain using frontward modified discrete cosine transform (MDCT). This is done by using filter banks that accept an appropriate number of time samples and convert them to frequency samples.
  • The frequency domain signal is quantized based on a psychoacoustic model and encoded.
  • Internal mistake correction codes are added.
  • The signal is stored or transmitted.
  • In social club to prevent decadent samples, a modern implementation of the Luhn mod North algorithm is practical to each frame.[41]

The MPEG-iv audio standard does not define a single or pocket-sized set of highly efficient pinch schemes but rather a circuitous toolbox to perform a wide range of operations from depression scrap charge per unit spoken language coding to loftier-quality audio coding and music synthesis.

  • The MPEG-4 sound coding algorithm family unit spans the range from depression bit charge per unit speech encoding (down to two kbit/s) to high-quality audio coding (at 64 kbit/s per channel and higher).
  • AAC offers sampling frequencies betwixt 8 kHz and 96 kHz and any number of channels between ane and 48.
  • In contrast to MP3's hybrid filter banking concern, AAC uses the modified discrete cosine transform (MDCT) together with the increased window lengths of 1024 or 960 points.

AAC encoders can switch dynamically between a single MDCT cake of length 1024 points or 8 blocks of 128 points (or between 960 points and 120 points, respectively).

  • If a signal change or a transient occurs, 8 shorter windows of 128/120 points each are chosen for their amend temporal resolution.
  • By default, the longer 1024-point/960-bespeak window is otherwise used because the increased frequency resolution allows for a more sophisticated psychoacoustic model, resulting in improved coding efficiency.

Modular encoding [edit]

AAC takes a modular arroyo to encoding. Depending on the complexity of the bitstream to be encoded, the desired performance and the acceptable output, implementers may create profiles to define which of a specific set of tools they desire to utilize for a particular application.

The MPEG-2 Role 7 standard (Advanced Sound Coding) was outset published in 1997 and offers three default profiles:[two] [42]

  • Low Complexity (LC) – the simplest and nigh widely used and supported
  • Main Profile (Main) – like the LC profile, with the addition of backwards prediction
  • Scalable Sample Rate (SSR) a.k.a. Sample-Rate Scalable (SRS)

The MPEG-4 Part 3 standard (MPEG-four Audio) divers various new compression tools (a.m.a. Audio Object Types) and their usage in make new profiles. AAC is non used in some of the MPEG-iv Audio profiles. The MPEG-2 Part 7 AAC LC contour, AAC Primary contour and AAC SSR contour are combined with Perceptual Noise Substitution and defined in the MPEG-4 Audio standard as Audio Object Types (under the name AAC LC, AAC Chief and AAC SSR). These are combined with other Object Types in MPEG-4 Audio profiles.[25] Here is a list of some audio profiles defined in the MPEG-iv standard:[33] [43]

  • Chief Sound Contour – divers in 1999, uses most of the MPEG-4 Audio Object Types (AAC Chief, AAC-LC, AAC-SSR, AAC-LTP, AAC Scalable, TwinVQ, CELP, HVXC, TTSI, Master synthesis)
  • Scalable Audio Contour – defined in 1999, uses AAC-LC, AAC-LTP, AAC Scalable, TwinVQ, CELP, HVXC, TTSI
  • Speech Audio Profile – defined in 1999, uses CELP, HVXC, TTSI
  • Synthetic Sound Contour – defined in 1999, TTSI, Main synthesis
  • High Quality Sound Profile – divers in 2000, uses AAC-LC, AAC-LTP, AAC Scalable, CELP, ER-AAC-LC, ER-AAC-LTP, ER-AAC Scalable, ER-CELP
  • Low Delay Audio Profile – divers in 2000, uses CELP, HVXC, TTSI, ER-AAC-LD, ER-CELP, ER-HVXC
  • Depression Delay AAC v2 - defined in 2012, uses AAC-LD, AAC-ELD and AAC-ELDv2[44]
  • Mobile Audio Internetworking Profile – defined in 2000, uses ER-AAC-LC, ER-AAC-Scalable, ER-TwinVQ, ER-BSAC, ER-AAC-LD
  • AAC Profile – defined in 2003, uses AAC-LC
  • High Efficiency AAC Contour – defined in 2003, uses AAC-LC, SBR
  • Loftier Efficiency AAC v2 Profile – defined in 2006, uses AAC-LC, SBR, PS
  • Extended Loftier Efficiency AAC xHE-AAC – defined in 2012, uses USAC

One of many improvements in MPEG-four Audio is an Object Type chosen Long Term Prediction (LTP), which is an comeback of the Main profile using a forward predictor with lower computational complexity.[27]

AAC error protection toolkit [edit]

Applying error protection enables error correction up to a certain extent. Mistake correcting codes are unremarkably practical every bit to the whole payload. However, since dissimilar parts of an AAC payload show different sensitivity to manual errors, this would not exist a very efficient arroyo.

The AAC payload can be subdivided into parts with different mistake sensitivities.

  • Contained mistake correcting codes tin be practical to any of these parts using the Error Protection (EP) tool defined in MPEG-4 Audio standard.
  • This toolkit provides the mistake correcting adequacy to the most sensitive parts of the payload in club to keep the additional overhead low.
  • The toolkit is backwardly compatible with simpler and pre-existing AAC decoders. A great deal of the toolkit's error correction functions are based around spreading information about the audio bespeak more evenly in the datastream.

Mistake Resilient (ER) AAC [edit]

Error Resilience (ER) techniques can be used to make the coding scheme itself more robust against errors.

For AAC, three custom-tailored methods were adult and divers in MPEG-4 Audio

  • Huffman Codeword Reordering (HCR) to avert error propagation within spectral data
  • Virtual Codebooks (VCB11) to detect serious errors within spectral data
  • Reversible Variable Length Code (RVLC) to reduce error propagation within scale gene information

AAC Low Delay [edit]

The audio coding standards MPEG-iv Low Delay (AAC-LD), Enhanced Low Delay (AAC-ELD), and Enhanced Depression Delay v2 (AAC-ELDv2) as defined in ISO/IEC 14496-iii:2009 and ISO/IEC 14496-three:2009/Amd 3 are designed to combine the advantages of perceptual audio coding with the low filibuster necessary for ii-fashion communication. They are closely derived from the MPEG-2 Advanced Audio Coding (AAC) format.[45] [46] [47] AAC-ELD is recommended by GSMA every bit super-wideband vocalism codec in the IMS Profile for High Definition Video Briefing (HDVC) Service.[48]

Licensing and patents [edit]

No licenses or payments are required for a user to stream or distribute content in AAC format.[49] This reason alone might have made AAC a more than attractive format to distribute content than its predecessor MP3, particularly for streaming content (such as Internet radio) depending on the use case.

Withal, a patent license is[ when? ] required for all manufacturers or developers of AAC codecs.[50] For this reason, gratis and open source software implementations such as FFmpeg and FAAC may be distributed in source grade just, in order to avoid patent infringement. (Encounter below under Products that support AAC, Software.)

The AAC patent holders include Bong Labs, Dolby, Fraunhofer, LG Electronics, NEC, NTT Docomo, Panasonic, Sony Corporation,[one] ETRI, JVC Kenwood, Philips, Microsoft, and NTT.[14]

Extensions and improvements [edit]

Some extensions take been added to the first AAC standard (defined in MPEG-2 Part vii in 1997):

  • Perceptual Dissonance Exchange (PNS), added in MPEG-four in 1999. It allows the coding of noise equally pseudorandom data.
  • Long Term Predictor (LTP), added in MPEG-4 in 1999. It is a forwards predictor with lower computational complexity.[27]
  • Error Resilience (ER), added in MPEG-four Audio version 2 in 2000, used for transport over error prone channels[51]
  • AAC-LD (Depression Delay), divers in 2000, used for real-time conversation applications
  • High Efficiency AAC (HE-AAC), a.k.a. aacPlus v1 or AAC+, the combination of SBR (Spectral Band Replication) and AAC LC. Used for low bitrates. Defined in 2003.
  • HE-AAC v2, a.yard.a. aacPlus v2, eAAC+ or Enhanced aacPlus, the combination of Parametric Stereo (PS) and HE-AAC; used for even lower bitrates. Defined in 2004 and 2006.
  • MPEG-4 Scalable To Lossless (SLS), Not yet published,[52] can supplement an AAC stream to provide a lossless decoding option, such every bit in Fraunhofer IIS's "Hard disk drive-AAC" production

Container formats [edit]

In addition to the MP4, 3GP and other container formats based on ISO base media file format for file storage, AAC audio data was commencement packaged in a file for the MPEG-2 standard using Audio Data Interchange Format (ADIF),[53] consisting of a unmarried header followed by the raw AAC sound data blocks.[54] However, if the data is to be streamed inside an MPEG-2 send stream, a self-synchronizing format called an Audio Data Transport Stream (ADTS) is used, consisting of a series of frames, each frame having a header followed past the AAC audio data.[53] This file and streaming-based format are defined in MPEG-ii Office 7, merely are only considered informative past MPEG-four, so an MPEG-4 decoder does not demand to back up either format.[53] These containers, as well as a raw AAC stream, may conduct the .aac file extension. MPEG-4 Part 3 also defines its own self-synchronizing format chosen a Low Overhead Audio Stream (LOAS) that encapsulates not only AAC, but any MPEG-4 audio compression scheme such every bit TwinVQ and ALS. This format is what was defined for apply in DVB transport streams when encoders use either SBR or parametric stereo AAC extensions. However, it is restricted to but a unmarried not-multiplexed AAC stream. This format is also referred to equally a Depression Overhead Audio Ship Multiplex (LATM), which is just an interleaved multiple stream version of a LOAS.[53]

Products that support AAC [edit]

HDTV Standards [edit]

Japanese ISDB-T [edit]

In December 2003, Japan started broadcasting terrestrial DTV ISDB-T standard that implements MPEG-2 video and MPEG-2 AAC sound. In April 2006 Nihon started broadcasting the ISDB-T mobile sub-program, called 1seg, that was the first implementation of video H.264/AVC with sound HE-AAC in Terrestrial HDTV dissemination service on the planet.

International ISDB-Tb [edit]

In December 2007, Brazil started broadcasting terrestrial DTV standard chosen International ISDB-Tb that implements video coding H.264/AVC with audio AAC-LC on main program (unmarried or multi) and video H.264/AVC with sound HE-AACv2 in the 1seg mobile sub-programme.

DVB [edit]

The ETSI, the standards governing body for the DVB suite, supports AAC, HE-AAC and HE-AAC v2 audio coding in DVB applications since at to the lowest degree 2004.[55] DVB broadcasts which utilise the H.264 compression for video unremarkably use HE-AAC for sound.[ citation needed ]

Hardware [edit]

iTunes and iPod [edit]

In Apr 2003, Apple brought mainstream attending to AAC by announcing that its iTunes and iPod products would support songs in MPEG-4 AAC format (via a firmware update for older iPods). Customers could download music in a closed-source Digital Rights Management (DRM)-restricted form of 128 kbps AAC (meet FairPlay) via the iTunes Store or create files without DRM from their ain CDs using iTunes. In later years, Apple began offer music videos and movies, which also utilize AAC for sound encoding.

On May 29, 2007, Apple tree began selling songs and music videos from participating tape labels at higher bitrate (256 kbps cVBR) and complimentary of DRM, a format dubbed "iTunes Plus" . These files generally attach to the AAC standard and are playable on many non-Apple products but they practice include custom iTunes information such as album artwork and a buy receipt, so as to identify the client in case the file is leaked out onto peer-to-peer networks. It is possible, however, to remove these custom tags to restore interoperability with players that conform strictly to the AAC specification. As of Jan 6, 2009, nearly all music on the U.s. regioned iTunes Store became DRM-free, with the remainder becoming DRM-free by the cease of March 2009.[56]

iTunes offers a "Variable Scrap Rate" encoding option which encodes AAC tracks in the Constrained Variable Bitrate scheme (a less strict variant of ABR encoding); the underlying QuickTime API does offer a true VBR encoding profile however.[57]

As of September 2009, Apple has added support for HE-AAC (which is fully office of the MP4 standard) only for radio streams, not file playback, and iTunes still lacks support for true VBR encoding.

Other portable players [edit]

  • Archos
  • Cowon (unofficially supported on some models)
  • Creative Zen Portable
  • Fiio (all current models)
  • Nintendo 3DS
  • Nintendo DSi
  • Philips GoGear Muse
  • PlayStation Portable (PSP) with firmware 2.0 or greater
  • Samsung YEPP
  • SanDisk Sansa (some models)
  • Walkman
  • Zune
  • Any portable player that fully supports the Rockbox third party firmware

Mobile phones [edit]

For a number of years, many mobile phones from manufacturers such as Nokia, Motorola, Samsung, Sony Ericsson, BenQ-Siemens and Philips have supported AAC playback. The first such phone was the Nokia 5510 released in 2002 which likewise plays MP3s. However, this telephone was a commercial failure[ commendation needed ] and such phones with integrated music players did not gain mainstream popularity until 2005 when the trend of having AAC also as MP3 back up continued. Most new smartphones and music-themed phones support playback of these formats.

  • Sony Ericsson phones back up various AAC formats in MP4 container. AAC-LC is supported in all phones commencement with K700, phones beginning with W550 take support of HE-AAC. The latest devices such every bit the P990, K610, W890i and later back up HE-AAC v2.
  • Nokia XpressMusic and other new generation Nokia multimedia phones like Due north- and E-Series too support AAC format in LC, HE, M4A and HEv2 profiles. These also supports playing LTP-encoded AAC audio.
  • BlackBerry phones running the BlackBerry 10 operating system support AAC playback natively. Select previous generation BlackBerry OS devices too support AAC.
  • bada OS
  • Apple tree's iPhone supports AAC and FairPlay protected AAC files formerly used equally the default encoding format in the iTunes Store until the removal of DRM restrictions in March 2009.
  • Android ii.3[58] and later supports AAC-LC, HE-AAC and HE-AAC v2 in MP4 or M4A containers along with several other sound formats. Android 3.1 and later supports raw ADTS files. Android four.1 can encode AAC.[59]
  • WebOS past HP/Palm supports AAC, AAC+, eAAC+, and .m4a containers in its native music player every bit well every bit several third-party players. However, it does not support Apple's FairPlay DRM files downloaded from iTunes.[60]
  • Windows Phone's Silverlight runtime supports AAC-LC, HE-AAC and HE-AAC v2 decoding.

Other devices [edit]

  • Apple's iPad: Supports AAC and FairPlay protected AAC files used every bit the default encoding format in the iTunes Store
  • Palm OS PDAs: Many Palm OS based PDAs and smartphones can play AAC and HE-AAC with the third party software Pocket Tunes. Version 4.0, released in December 2006, added support for native AAC and HE-AAC files. The AAC codec for TCPMP, a pop video thespian, was withdrawn after version 0.66 due to patent issues, simply tin yet be downloaded from sites other than corecodec.org. CorePlayer, the commercial follow-on to TCPMP, includes AAC back up. Other Palm Os programs supporting AAC include Kinoma Actor and AeroPlayer.
  • Windows Mobile: Supports AAC either by the native Windows Media Thespian or past third-political party products (TCPMP, CorePlayer)[ commendation needed ]
  • Epson: Supports AAC playback in the P-2000 and P-4000 Multimedia/Photograph Storage Viewers
  • Sony Reader: plays M4A files containing AAC, and displays metadata created by iTunes. Other Sony products, including the A and E serial Network Walkmans, support AAC with firmware updates (released May 2006) while the S series supports it out of the box.
  • Sonos Digital Media Actor: supports playback of AAC files
  • Barnes & Noble Nook Color: supports playback of AAC encoded files
  • Roku SoundBridge: a network audio thespian, supports playback of AAC encoded files
  • Squeezebox: network audio player (made past Slim Devices, a Logitech company) that supports playback of AAC files
  • PlayStation three: supports encoding and decoding of AAC files
  • Xbox 360: supports streaming of AAC through the Zune software, and of supported iPods connected through the USB port
  • Wii: supports AAC files through version 1.1 of the Photo Channel as of December eleven, 2007. All AAC profiles and bitrates are supported equally long equally it is in the .m4a file extension. This update removed MP3 compatibility, merely users who have installed this may freely downgrade to the old version if they wish.[61]
  • Livescribe Pulse and Echo Smartpens: record and store audio in AAC format. The audio files tin exist replayed using the pen'due south integrated speaker, attached headphones, or on a computer using the Livescribe Desktop software. The AAC files are stored in the user's "My Documents" folder of the Windows OS and tin be distributed and played without specialized hardware or software from Livescribe.
  • Google Chromecast: supports playback of LC-AAC and HE-AAC audio[62]

Software [edit]

Virtually all current computer media players include built-in decoders for AAC, or can use a library to decode it. On Microsoft Windows, DirectShow tin be used this way with the corresponding filters to enable AAC playback in any DirectShow based thespian. Mac Os Ten supports AAC via the QuickTime libraries.

Adobe Flash Player, since version 9 update iii, can also play back AAC streams.[63] [64] Since Flash Role player is likewise a browser plugin, it can play AAC files through a browser as well.

The Rockbox open source firmware (available for multiple portable players) besides offers support for AAC to varying degrees, depending on the model of actor and the AAC profile.

Optional iPod support (playback of unprotected AAC files) for the Xbox 360 is bachelor as a free download from Xbox Alive.[65]

The following is a non-comprehensive list of other software histrion applications:

  • 3ivx MPEG-4: a suite of DirectShow and QuickTime plugins which support AAC encoding or AAC/ HE-AAC decoding in any DirectShow awarding
  • CorePlayer: likewise supports LC and HE AAC
  • ffdshow: a free open up source DirectShow filter for Microsoft Windows that uses FAAD2 to back up AAC decoding
  • foobar2000: a freeware audio thespian for Windows that supports LC and HE AAC
  • KMPlayer
  • MediaMonkey
  • AIMP
  • Media Player Classic Home Cinema
  • mp3tag
  • MPlayer or xine: often used equally AAC decoders on Linux or Macintosh
  • MusicBee: an advanced music manager and player that likewise supports encoding and ripping through a plugin
  • RealPlayer: includes RealNetworks' RealAudio 10 AAC encoder
  • Songbird: supports AAC on Windows, Linux and Mac Bone X , including the DRM rights direction encoding used for purchased music from the iTunes Store, with a plug-in
  • Sony SonicStage
  • VLC media player: supports playback and encoding of MP4 and raw AAC files
  • Winamp for Windows: includes an AAC encoder that supports LC and HE AAC
  • Windows Media Player 12: released with Windows 7, supports playback of AAC files natively
  • Another Real: Rhapsody supports the RealAudio AAC codec, in addition to offering subscription tracks encoded with AAC
  • XBMC: supports AAC (both LC and HE).
  • XMMS: supports MP4 playback using a plugin provided past the faad2 library

Some of these players (e.g., foobar2000, Winamp, and VLC) too support the decoding of ADTS (Audio Data Transport Stream) using the SHOUTcast protocol. Plug-ins for Winamp and foobar2000 enable the creation of such streams.

Nero Digital Audio [edit]

In May 2006, Nero AG released an AAC encoding tool complimentary of charge, Nero Digital Audio (the AAC codec portion has become Nero AAC Codec),[66] which is capable of encoding LC-AAC, HE-AAC and HE-AAC v2 streams. The tool is a Command Line Interface tool merely. A separate utility is besides included to decode to PCM WAV.

Diverse tools including the foobar2000 audio player and MediaCoder can provide a GUI for this encoder.

FAAC and FAAD2 [edit]

Main commodity: FAAC

FAAC and FAAD2 stand for Freeware Advanced Audio Coder and Decoder two respectively. FAAC supports sound object types LC, Main and LTP.[67] FAAD2 supports audio object types LC, Main, LTP, SBR and PS.[68] Although FAAD2 is free software, FAAC is non free software.

Fraunhofer FDK AAC [edit]

A Fraunhofer-authored open up-source encoder/decoder included in Android has been ported to other platforms. It is the recommended AAC encoder of FFmpeg.[ citation needed ]

FFmpeg and Libav [edit]

The native AAC encoder created in FFmpeg'southward libavcodec, and forked with Libav, was considered experimental and poor. A meaning corporeality of work was done for the 3.0 release of FFmpeg (February 2016) to make its version usable and competitive with the rest of the AAC encoders.[69] Libav has not merged this work and continues to apply the older version of the AAC encoder. These encoders are LGPL-licensed open-source and tin can be congenital for any platform that the FFmpeg or Libav frameworks can be congenital.

Both FFmpeg and Libav can use the Fraunhofer FDK AAC library via libfdk-aac, and while the FFmpeg native encoder has get stable and skilful enough for common use, FDK is still considered the highest quality encoder available for use with FFmpeg.[70] Libav as well recommends using FDK AAC if it is available.[71]

See also [edit]

  • Comparison of sound coding formats
  • AAC-LD
  • MPEG-4 Part 14 (container format)
  • ALAC – Apple'southward own lossless codec
  • Vorbis – the main open, royalty-free competitor to AAC and MP3
  • Opus – an open, royalty-free codec for both pre-encoded and interactive use, standardized in 2012

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External links [edit]

  • Fraunhofer audio codecs
  • AudioCoding.com Archived 2006-08-25 at the Wayback Motorcar – habitation of FAAC and FAAD2
  • Official MPEG web site
  • AAC improvements and extensions (2004)
  • RFC 3016 - RTP Payload Format for MPEG-iv Audio/Visual Streams
  • RFC 3640 - RTP Payload Format for Transport of MPEG-4 Elementary Streams
  • RFC 4281 - The Codecs Parameter for "Bucket" Media Types
  • RFC 4337 - MIME Type Registration for MPEG-4

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Source: https://en.wikipedia.org/wiki/Advanced_Audio_Coding

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