Advanced Audio Coding (AAC) is a standardized, lossy A lossy compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original, but is close enough to be useful in some way. Lossy compression is most commonly used to compress multimedia data , especially in applications such as streaming media and internet telephony. By contrast, compression Audio compression is a form of data compression designed to reduce the size of audio files. Audio compression algorithms are implemented in computer software as audio codecs. Generic data compression algorithms perform poorly with audio data, seldom reducing file sizes much below 87% of the original, and are not designed for use in real time and encoding An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format, or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size scheme for digital audio Digital audio uses digital signals for sound reproduction. This includes analog-to-digital conversion, digital-to-analog conversion, storage, and transmission. In effect, the system commonly referred to as digital is in fact a discrete-time, discrete-level analog of a previous electrical analog. While modern systems can be quite subtle in their. Designed to be the successor of the MP3 MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard of digital audio compression for the transfer and playback of music on digital audio players. MP3 is an audio-specific format, AAC generally achieves better sound quality than MP3 at many bit rates In telecommunications and computing, bitrate is the number of bits that are conveyed or processed per unit of time.

AAC has been standardized by ISO The International Organization for Standardization , widely known as ISO (pronounced /ˈaɪsoʊ/), is an international-standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promulgates worldwide proprietary industrial and commercial standards. It is and IEC, as part of the MPEG-2 MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth and MPEG-4 MPEG-4 is a patented collection of methods defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal standard ISO/IEC 14496. Uses of MPEG-4 specifications. The MPEG-2 standard contains several audio coding methods, including the MP3 coding scheme. AAC is able to include 48 full-bandwidth In computer networking and computer science, digital bandwidth, network bandwidth or just bandwidth is a measure of available or consumed data communication resources expressed in bit/s or multiples of it (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 Stereophonic sound, commonly called stereo, is the reproduction of sound, using two or more independent audio channels, through a symmetrical configuration of loudspeakers, in such a way as to create the impression of sound heard from various directions, as in natural hearing. It is often contrasted with monophonic, or "mono" sound, is satisfactory to modest requirements at 96 kbit/s in joint stereo mode, however hi-fi transparency In data compression or psychoacoustics, transparency is the ideal result of lossy data compression. If a lossily compressed result is perceptually indistinguishable from the uncompressed input, then the compression can be declared to be transparent. In other words, transparency is the situation where compression artifacts are nonexistent or demands data rates of at least 128kbit/s (VBR Variable bitrate is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows a higher bitrate (and therefore more storage space) to be allocated to the more complex segments of media files). 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 320kbit/s for 5.1 audio.

AAC's best known use is as the default audio format of Apple Apple Inc. is an American multinational corporation that designs and manufactures consumer electronics and software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone. Apple software includes the Mac OS X operating system, the iTunes media browser, the iLife suite of multimedia and creativity's iPhone The iPhone is an Internet-connected, multimedia smartphone designed and marketed by Apple Inc. Because its minimal hardware interface lacks a physical keyboard, the multi-touch screen renders a virtual keyboard when necessary. The iPhone functions as a camera phone , a portable media player (equivalent to a video iPod), and an Internet client (, iPod iPod is a brand of portable media players designed and marketed by Apple Inc. and launched on October 23, 2001). The product line-up includes the hard drive-based iPod Classic, the touchscreen iPod Touch, the video-capable iPod Nano, and the compact iPod Shuffle. The iPhone can function as an iPod but is generally treated as a separate product, iTunes iTunes is a proprietary digital media player application, used for playing and organizing digital music and video files. The program is also an interface to manage the contents on Apple's popular iPod digital media players as well as the iPhone. Additionally, iTunes can connect to the iTunes Store via the Internet to purchase and download music,, and the format used for all iTunes Store The iTunes Store is a software-based online digital media store operated by Apple Inc. Opening as the iTunes Music Store on April 28, 2003, it proved the viability of online music sales and is now the number-one music vendor in the United States. As of January 2009, the store has sold 6 billion songs, accounting for more than 70% of worldwide audio.

AAC is also the standard audio format for Sony Sony Corporation (TYO: 6758) is a multinational conglomerate corporation headquartered in Minato, Tokyo, Japan, and one of the world's largest media conglomerates with revenue exceeding ¥ 7.730.0 trillion, or $78.88 billion U.S. (FY2008). Sony is one of the leading manufacturers of electronics, video, communications, video game consoles, and's PlayStation 3 The PlayStation 3 is the third home video game console produced by Sony Computer Entertainment, and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles and is supported by Sony Sony Corporation (TYO: 6758) is a multinational conglomerate corporation headquartered in Minato, Tokyo, Japan, and one of the world's largest media conglomerates with revenue exceeding ¥ 7.730.0 trillion, or $78.88 billion U.S. (FY2008). Sony is one of the leading manufacturers of electronics, video, communications, video game consoles, and's Playstation Portable On October 17, 2004, Sony announced that the PSP would launch in Japan on December 12, 2004 at a price of ¥19,800 for the base model and ¥24,800 (about US$226 in 2004) for the Value System. The console's launch was a success with over 200,000 units sold the first day. They also sell different color variations in bundle packs, which cost more, latest generation of Sony Walkman, Walkman Phones from Sony Ericsson Sony Ericsson is a joint venture established on October 3, 2001 by the Japanese consumer electronics company Sony Corporation and the Swedish telecommunications company Ericsson to make mobile phones. The stated reason for this venture is to combine Sony's consumer electronics expertise with Ericsson's technological leadership in the, Nseries Phones from Nokia Nokia Corporation (OMX: NOK1V, NYSE: NOK, FWB: NOA3) is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki. Nokia is engaged in the manufacturing of mobile devices and in converging Internet and communications industries, with 128,445 employees in 120, Android In July 2005, Google acquired Android, Inc., a small startup company based in Palo Alto, California, USA. Android's co-founders who went to work at Google included Andy Rubin , Rich Miner (co-founder of Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile), and Chris White (headed design and interface development at WebTV). At the time, based phones, Nintendo Nintendo has produced several home and portable video game consoles since 1977. Home consoles include the Color TV Game , Nintendo Entertainment System/Famicom (NES, 1983), Super Nintendo Entertainment System/Super Famicom (SNES, 1990), Nintendo 64 (N64, 1996), Nintendo GameCube (GCN, 2001) and Wii (2006). Portable consoles include the Game &'s Wii The Wii is a home video game console released by Nintendo. As a seventh-generation console, the Wii primarily competes with Microsoft's Xbox 360 and Sony's PlayStation 3. Nintendo states that its console targets a broader demographic than that of both. As of December 31, 2008 the Wii leads the generation over the PlayStation 3 and Xbox 360 in (with the Photo Channel 1.1 update installed for Wii consoles purchased before late 2007), the Nintendo DSi The Nintendo DSi is a handheld game console produced by Nintendo, and the third iteration of the Nintendo DS handheld gaming console, following the Nintendo DS Lite. The DSi has launched in four key markets; Japan, Australasia (Oceania), Europe, and North America between 2008 and 2009, and the MPEG-4 MPEG-4 is a patented collection of methods defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal standard ISO/IEC 14496. Uses of MPEG-4 video standard.

High-Efficiency AAC is part of digital radio Digital radio describes radio technologies which carry information as a digital signal, by means of a digital modulation method. The most common meaning is digital audio broadcasting technologies, but the topic may also cover TV broadcasting as well as many two-way digital wireless communication technologies. The acronym DAB is synonymous with the standards like DAB+ Digital Audio Broadcasting , is a digital radio technology for broadcasting radio stations, used in several countries, particularly in Europe. As of 2006, approximately 1,000 stations worldwide broadcast in the DAB format and Digital Radio Mondiale Digital Radio Mondiale is a set of digital audio broadcasting technologies designed to work over the bands currently used for AM broadcasting, particularly shortwave. DRM can fit more channels than AM, at higher quality, into a given amount of bandwidth, using various MPEG-4 codecs.

Contents

History

AAC was developed with the cooperation and contributions of companies including Fraunhofer IIS The Fraunhofer Society is a German research organization with 58 institutes spread throughout Germany, each focusing on different fields of applied science (as opposed to the Max-Planck-Gesellschaft, which works primarily on basic science). It employs over 12,500, mainly scientists and engineers, with an annual research budget of about €1.2, AT&T Bell Laboratories, Dolby Dolby Laboratories, Inc. (NYSE: DLB) is a British-found USA-based company specializing in audio noise reduction and audio encoding/compression, Sony Corporation Sony Corporation is a multinational conglomerate corporation headquartered in Minato, Tokyo, Japan, and one of the world's largest media conglomerates with revenue exceeding ¥ 8,871,400 trillion (as of 2008) . Sony is one of the leading manufacturers of electronics, video, communications, video game consoles, and information technology products and Nokia Nokia Corporation (OMX: NOK1V, NYSE: NOK, FWB: NOA3) is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki. Nokia is engaged in the manufacturing of mobile devices and in converging Internet and communications industries, with 128,445 employees in 120, and was officially declared an international standard by the Moving Pictures Experts Group in April 1997. MPEG-2 AAC-LC profile consists of a base format very much like AT&T's PAC coding format,[1][2][3] with the addition of TNS,[4] the Dolby Kaiser Window described below, a nonuniform quantizer In digital signal processing, quantization is the process of approximating a continuous range of values by a relatively small set of discrete symbols or integer values. More specifically, a signal can be multi-dimensional and quantization need not be applied to all dimensions. Discrete signals (a common mathematical model) need not be quantized,, and a reworking of the bitstream format to handle up to 16 stereo, 16 mono, 16 LFE, and 16 commentary channels in one bitstream. The Main profile adds a set of recursive predictors that are calculated on each tap of the filterbank. The SSR uses a 4-band PQMF filterbank, with four shorter filterbanks following, in order to allow for scalable sampling rates.

Standardization

It is specified both as Part 7 of the MPEG-2 standard, and Part 3 of the MPEG-4 standard. As such, it can be referred to as MPEG-2 Part 7 and MPEG-4 Part 3 depending on its implementation, however it is most often referred to as MPEG-4 AAC, or AAC for short.

AAC was first specified in the standard MPEG-2 Part 7 (known formally as ISO The International Organization for Standardization , widely known as ISO (pronounced /ˈaɪsoʊ/), is an international-standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promulgates worldwide proprietary industrial and commercial standards. It is/IEC The International Electrotechnical Commission is a not-for-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology". IEC standards cover a vast range of technologies from power 13818-7:1997) in 1997 as a new "part" (distinct from ISO The International Organization for Standardization , widely known as ISO (pronounced /ˈaɪsoʊ/), is an international-standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promulgates worldwide proprietary industrial and commercial standards. It is/IEC The International Electrotechnical Commission is a not-for-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology". IEC standards cover a vast range of technologies from power 13818-3) in the MPEG-2 MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth family of international standards International standards are standards developed by international standards organizations. International standards are available for consideration and use, worldwide.

It was updated in MPEG-4 Part 3 MPEG-4 Part 3 is the third part of the ISO/IEC MPEG-4 international standard. It specifies audio coding methods (known formally as ISO/IEC 14496-3:1999) in 1999. The reference software is specified in MPEG-4 Part 4 and the conformance bit-streams are specified in MPEG-4 Part 5. A notable addition in this version of the standard is Perceptual Noise Substitution (PNS).

HE-AAC High-Efficiency Advanced Audio Coding is a lossy data compression scheme for digital audio. It is an extension of Low Complexity AAC (AAC LC) optimized for low-bitrate applications such as streaming audio. HE-AAC version 1 (HE-AAC v1) uses spectral band replication (SBR) to enhance the compression efficiency in the frequency domain. HE-AAC version (AAC with SBR Spectral band replication is a technology to enhance audio or speech codecs, especially at low bit rates and is based on harmonic redundancy in the frequency domain) was first standardized in ISO/IEC 14496-3:2001/Amd.1. HE-AAC v2 (AAC with Parametric Stereo) was first specified in ISO/IEC 14496-3:2001/Amd.4.[5]

The current version of the AAC standard is ISO/IEC 14496-3:2005 (with 14496-3:2005/Amd.2. for HE-AAC v2[6])

AAC+ v2 is also standardized by ETSI The European Telecommunications Standards Institute is an independent, non-profit, standardization organization in the telecommunications industry (equipment makers and network operators) in Europe, with worldwide projection. ETSI has been successful in standardizing the GSM cell phone system and the TETRA professional mobile radio system (European Telecommunications Standards Institute The European Telecommunications Standards Institute is an independent, non-profit, standardization organization in the telecommunications industry (equipment makers and network operators) in Europe, with worldwide projection. ETSI has been successful in standardizing the GSM cell phone system and the TETRA professional mobile radio system) as TS 102005.[5]

The MPEG-4 standard also contains other ways of compressing sound. These are low bit-rate and generally used for speech.

AAC's improvements over MP3

AAC was designed to improve on the MP3 MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard of digital audio compression for the transfer and playback of music on digital audio players. MP3 is an audio-specific format (which was specified in MPEG-1 MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to 1.5 Mbit/s without excessive quality loss, making Video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) possible and MPEG-2) by the ISO/IEC in 11172-3 and 13818-3.

Advanced Audio Coding is designed to be the successor of the MP3 format and demonstrates greater sound quality and transparency than MP3 files coded at the same bit rate[citation needed].

Improvements include:

Overall, the AAC format allows developers more flexibility to design codecs than MP3 does, and corrects many of the design choices made in the original MPEG-1 audio specification. This increased flexibility often leads to more concurrent encoding strategies and, as a result, to more efficient compression. However, in terms of whether AAC is better than MP3, the advantages of AAC are not entirely decisive, and the MP3 specification, although antiquated, has proven surprisingly robust in spite of considerable flaws. AAC and HE-AAC are better than MP3 at low bit rates (typically less than 128 kilobits per second)[citation needed]. This is especially true at very low bit rates where the superior stereo coding, pure MDCT, and more optimal transform window sizes leave MP3 unable to compete. However, as bit rate increases, the efficiency of an audio format becomes less important relative to the efficiency of the encoder's implementation, and the intrinsic advantage AAC holds over MP3 no longer dominates audio quality.

How AAC works

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

  1. Signal components that are perceptually irrelevant are discarded;
  2. Redundancies in the coded audio signal are eliminated.

The actual encoding process consists of the following steps:

The MPEG-4 audio standard does not define a single or small set of highly efficient compression schemes but rather a complex toolbox to perform a wide range of operations from low bitrate speech coding to high-quality audio coding and music synthesis.

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

Modular encoding

AAC takes a modular approach 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 want to use for a particular application. The standard offers four default profiles:

Depending on the AAC profile and the MP3 encoder, 96 kbit/s AAC can give nearly the same or better perceptual quality as 128 kbit/s MP3.[7]

AAC error protection toolkit

Applying error protection enables error correction up to a certain extent. Error correcting codes are usually applied equally to the whole payload. However, since different parts of an AAC payload show different sensitivity to transmission errors, this would not be a very efficient approach.

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

Error Resilient (ER) AAC

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

For AAC, three custom-tailored methods were developed and defined in MPEG-4 Audio

AAC Low Delay

Main article: AAC-LD

The MPEG-4 Low Delay Audio Coder (AAC-LD) is designed to combine the advantages of perceptual audio coding with the low delay necessary for two-way communication. It is closely derived from the MPEG-2 Advanced Audio Coding (AAC) format.

Licensing and patents

No licenses or payments are required to be able to stream or distribute content in AAC format.[8] This reason alone makes AAC a much more attractive format to distribute content than MP3, particularly for streaming content (such as Internet radio).

However, a patent license is required for all manufacturers or developers of AAC codecs.[9] It is for this reason FOSS implementations such as FAAC and FAAD are distributed in source form only, in order to avoid patent infringement. (See below under Products that support AAC, Software.)

Products that support AAC

HDTV Standards

Japanese ISDB-T

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

International ISDB-Tb

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

Hardware

iTunes and iPod

In April 2003, Apple Computer brought mainstream attention 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 proprietary Digital Rights Management (DRM)-restricted form of AAC (see FairPlay) via the iTunes Store or create files without DRM from their own CDs using iTunes. In later years, Apple began offering music videos and movies, which also use AAC for audio encoding.

On May 29, 2007, Apple began selling songs and music videos free of DRM from participating record labels. These files mostly adhere to the AAC standard and are playable on many non-Apple products but they do include custom iTunes information such as album artwork and a purchase receipt, so as to identify the customer 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.

iTunes supports a "Variable bit rate" (VBR) encoding option which encodes AAC tracks in an "Average bit rate" (ABR) scheme. As of October 2007, Apple has not added support for HE-AAC (which is fully part of the MP4 standard) or true VBR encoding to iTunes.

Other Portable Players

Mobile phones

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 also plays MP3s. However, this phone was a commercial failure and such phones with integrated music players did not gain mainstream popularity until 2005 when the trend of having AAC as well as MP3 support continued. Most new smartphones and music-themed phones support playback of these formats.

Other devices

Software

A very common program supporting AAC playback is Flash player, version 9, update 3 and above.[11] [12] However, since flash player is a browser plugin, it can only play AAC files through a browser.

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

Optional iPod support (playback of unprotected AAC files) for the Xbox 360 is available as a free download from Xbox Live.[13]

Other software media players

Almost all current computer media players include built-in decoders for AAC, or can utilize a library to decode it. On Microsoft Windows, DirectShow can be utilized this way with the corresponding filters to enable AAC playback in any DirectShow based player. Software player applications of particular note include:

Some of these players (e.g., foobar2000, Winamp, and VLC) also support the decoding of ADTS (Audio Data Transport Stream) or MP4-contained AAC streamed over HTTP using the SHOUTcast protocol. Plug-ins for Winamp and foobar2000 enable the creation of such streams.

Nero Digital Audio

In May 2006, Nero AG released an AAC encoding tool free of charge, Nero Digital Audio,[14] which is capable of encoding LC-AAC, HE-AAC and HE-AAC v2 streams. The tool is a Command Line Interface tool only, and a separate utility is included to decode to PCM WAV.

Various tools including the foobar2000 audio player, MeGUI encoding front end and dBpoweramp can provide a GUI for the encoder.

FAAC and FAAD2

FAAC and FAAD2 stand for Freeware Advanced Audio Coder and Decoder 2 respectively, collectively make up an open source implementation of AAC.

Extensions and improvements

Some extensions have been added to the original AAC standard:

Container formats

In addition to the MP4 container format for storage, AAC audio data may be packaged in a more basic format called Audio Data Interchange Format (ADIF),[15] consisting of a single header followed by the raw AAC audio data blocks.[16] Alternatively, it may be packaged in a streaming format called Audio Data Transport Stream (ADTS), consisting of a series of frames, each frame having a header followed by the AAC audio data.[15] Both formats are defined in MPEG-2 part 7, but are only considered informative by MPEG-4, so an MPEG-4 decoder does not need to support either format.[15] Two more formats are defined in MPEG-4 part 3: Low-overhead MPEG-4 Audio Transport Multiplex (LATM), which provides a way to combine separate audio payloads, and Low Overhead Audio Stream (LOAS), a self-synchronizing streaming format.[15]

See also

Notes

  1. ^ Johnston, J. D. and Ferreira, A. J., "Sum-difference stereo transform coding," ICASSP '92, March, 1992, pp. II-569-572.
  2. ^ Sinha, D. and Johnston, J. D., "Audio compression at low bit rates using a signal adaptive switched filterbank," IEEE ASSP, 1996, pp. 1053-1057.
  3. ^ Johnston, J. D., Sinha, D., Dorward, S. and Quackenbush, S., "AT&T perceptual audio coder (PAC)" in Collected Papers on Digital Audio Bit-Rate Reduction, Gilchrist, N. and Grewin, C. (Ed.), Audio Engineering Society, 1996.
  4. ^ Herre, J. and Johnston, J. D., "Enhancing the performance of perceptual audio coders by using temporal noise shaping," AES 101st Convention, no. preprint 4384, 1996
  5. ^ a b http://www.codingtechnologies.com/products/assets/CT_aacPlus_whitepaper.pdf
  6. ^ ISO/IEC 14496-3:2005/Amd.2 [1]
  7. ^ Apple - QuickTime - Technologies - AAC Audio
  8. ^ Via Licensing. "AAC Licensing FAQ Q5". http://www.vialicensing.com/Licensing/AAC_FAQ.cfm?faq=5#5.
  9. ^ Via Licensing. "AAC License Fees". http://www.vialicensing.com/Licensing/AAC_fees.cfm.
  10. ^ | Nintendo - Customer Service | Wii - Photo Channel
  11. ^ http://www.adobe.com/products/player_census/flashplayer/version_penetration.html
  12. ^ http://www.adobe.com/aboutadobe/pressroom/pressreleases/200712/120407adobemoviestar.html
  13. ^ Xbox.com | System Use - Use an Apple iPod with Xbox 360
  14. ^ http://www.nero.com/eng/downloads-nerodigital-nero-aac-codec.php
  15. ^ a b c d Wolters, Martin; Kristofer Kjorling, Daniel Homm, Heiko Purnhagen (PDF). A closer look into MPEG-4 High Efficiency AAC. pp. 3. http://www.telos-systems.com/techtalk/hosted/HE-AAC.pdf. Retrieved on 2008-07-31. Presented at the 115th Convention of the Audio Engineering Society, 10-13 October 2003.
  16. ^ "Advanced Audio Coding (MPEG-2), Audio Data Interchange Format". Library of Congress / National Digital Information Infrastructure and Preservation Program. 2007-03-07. http://www.digitalpreservation.gov/formats/fdd/fdd000112.shtml. Retrieved on 2008-07-31.

External links

Multimedia compression formats
Video compression
ISO/IEC MJPEG · Motion JPEG 2000 · MPEG-1 · MPEG-2 · MPEG-4 ASP · MPEG-4/AVC
ITU-T H.120 · H.261 · H.262 · H.263 · H.264 · H.265
Others AMV · AVS · Bink · Dirac · Indeo · Pixlet · RealVideo · RTVideo · SheerVideo · CineForm · Smacker · Theora · VC-1 · VP6 · VP7 · VP8 · WMV · XVD
Audio compression
ISO/IEC MPEG-1 Layer III (MP3) · MPEG-1 Layer II · MPEG-1 Layer I · AAC · HE-AAC
ITU-T G.711 · G.718 · G.719 · G.722 · G.722.1 · G.722.2 · G.723 · G.723.1 · G.726 · G.728 · G.729 · G.729.1 · G.729a
Others AC3 · AMR · Apple Lossless · ATRAC · DRA · FLAC · iLBC · Monkey's Audio · μ-law · Musepack · Nellymoser · OptimFROG · RealAudio · RTAudio · SHN · Siren · Speex · Vorbis · WavPack · WMA · TAK · True Audio
Image compression
ISO/IEC/ITU-T JPEG · JPEG 2000 · lossless JPEG · JBIG · JBIG2 · PNG · WBMP
Others APNG · BMP · EXR · GIF · ICER · ILBM · MNG · PCX · PGF · TGA · TIFF · JPEG XR / HD Photo
Media containers
General 3GP · ASF · AVI · Bink · BXF · DMF · DPX · EVO · FLV · VVF · Matroska · MPEG-PS · MPEG-TS · MP4 · MXF · GXF · Ogg · Ogg Media · QuickTime · RealMedia · Smacker · RIFF · VOB
Audio only AIFF · AU · WAV
See for methods and for codecs
High-definition (HD)
Concepts High-definition video • High-definition television • High-definition audio • Wireless HDMI
Analog broadcast (All defunct): 819 line system • HD MAC • MUSE (Hi-Vision)
Digital broadcast ATSC • DVB • ISDB • SBTVD • DMB-T/H
Audio Dolby Digital (5.1) • MPEG-1 Layer II • PCM • LPCM • DXD • DSD • AAC
Filming and storage HDV • DCI
HD media and compression Blu-ray Disc • HD DVD(Discontinued) • HD VMD • D-VHS • Super Audio CD • DVD-Audio • MPEG-2 • H.264 • VC-1
Connectors Component • HDMI • DVI • DisplayPort • VGA
Deployments List of digital television deployments by country

Categories: Audio codecs | Computer file formats | MPEG | Lossy compression algorithms | ISO standards | IEC standards | Open formats closed by software patents

 

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Any good, FREE, sites to stream my radio station through?
Q. I currently have blog talk radio. But the quality of the audio streaming SUCKS, and the coding of the web page itself also SUCKS. I was wondering if anyone knew of any free online radio hosts that let u upload your mp3s to their site and stream it? Pretty much like blog tak radio. Thanks in advanced. P.S. Ive heard of shoutcast but i dont know how to set all that stuff up.
Asked by BeepyCheesy - Sat Apr 18 10:33:56 2009 - - 2 Answers - 0 Comments
Yahoo Answers Search: Advanced Audio Coding,
Fri Jun 26 01:28:04 2009
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