Editing Audio file format

{{Short description|Computer format for digital audio}}

[[File:Audio formats.jpg|thumb|Audio file icons of various formats]]

An '''audio file format''' is a [[file format]] for storing [[digital audio]] data on a [[computer]] system. The bit layout of the audio data (excluding [[metadata]]) is called the [[audio coding format]] and can be uncompressed, or [[audio compression (data)|compressed]] to reduce the file size, often using [[lossy compression]]. The data can be a raw [[bitstream]] in an audio coding format, but it is usually embedded in a [[container format]] or an audio data format with defined storage layer.

==Format types==

It is important to distinguish between the [[audio coding format]], the [[Container format (digital)|container]] containing the [[Raw audio format|raw audio data]], and an [[audio codec]]. A codec performs the encoding and decoding of the raw audio data while this encoded data is (usually) stored in a container file. Although most audio file formats support only one type of audio coding data (created with an [[audio codec|audio coder]]), a multimedia container format (as [[Matroska]] or [[Audio Video Interleave|AVI]]) may support multiple types of audio and video data.

There are three major groups of audio file formats:

* Uncompressed audio formats, such as [[WAV]], [[Audio Interchange File Format|AIFF]], [[Au file format|AU]] or [[raw audio format|raw]] header-less [[PCM]]; Note wav can alternatively use compression.
* Formats with [[lossless compression]], such as [[FLAC]], [[Monkey's Audio]] ([[filename extension]] <code>.ape</code>), [[WavPack]] ([[filename extension]] <code>.wv</code>), TTA, [[ATRAC]] Advanced Lossless, [[Apple Lossless|ALAC]], [[MPEG-4 SLS]], [[MPEG-4 ALS]], [[MPEG-4 DST]], [[Windows Media Audio#Windows Media Audio Lossless|Windows Media Audio Lossless (WMA Lossless)]], and [[Shorten (file format)|Shorten]] (SHN).
* Formats with [[lossy compression]], such as [[Opus (audio format)|Opus]], [[MP3]], [[Vorbis]], [[Musepack]], [[Advanced Audio Coding|AAC]], [[ATRAC]] and [[Windows Media Audio#WIndows Media Audio Lossy|Windows Media Audio Lossy (WMA lossy)]].

===Uncompressed audio format===
{{See also|Raw audio format | Uncompressed video}}
One major uncompressed audio format, [[LPCM]], is the same variety of PCM as used in [[Compact Disc Digital Audio]] and is the format most commonly accepted by low level audio [[API]]s and [[D/A converter]] hardware. Although LPCM can be stored on a computer as a [[raw audio format]], it is usually stored in a <code>.wav</code> file on [[Windows]] or in a <code>.aiff</code> file on [[macOS]]. The [[Audio Interchange File Format]] (AIFF) format is based on the [[Interchange File Format]] (IFF), and the WAV format is based on the similar [[Resource Interchange File Format]] (RIFF). WAV and AIFF are designed to store a wide variety of audio formats, lossless and lossy; they just add a small, [[metadata]]-containing header before the audio data to declare the format of the audio data, such as LPCM with a particular [[sampling (signal processing)|sample rate]], [[audio bit depth|bit depth]], [[endianness]] and number of [[audio channel|channels]]. Since WAV and AIFF are widely supported and can store LPCM, they are suitable file formats for storing and archiving an original recording.

[[Broadcast Wave Format|BWF]] (Broadcast Wave Format) is a standard audio format created by the [[European Broadcasting Union]] as a successor to WAV. Among other enhancements, BWF allows more robust [[metadata]] to be stored in the file. See ''[[Broadcast Wave Format|European Broadcasting Union: Specification of the Broadcast Wave Format]]'' (EBU Technical document 3285, July 1997). This is the primary recording format used in many professional audio workstations in the television and film industry. BWF files include a standardized [[timestamp]] reference which allows for easy synchronization with a separate picture element. Stand-alone, file based, multi-track recorders from AETA,<ref>{{Cite web|url=http://www.aeta-audio.com/ |title=AETA AUDIO SYSTEMS: home |date=2016-01-29 |url-status=dead |archive-url=https://web.archive.org/web/20160129100145/http://www.aeta-audio.com/ |archive-date=January 29, 2016 }}</ref> Sound Devices,<ref>{{cite web|url=http://www.sounddevices.com/|title=Sound Devices - Home|website=www.sounddevices.com}}</ref> Zaxcom,<ref>{{cite web|url=https://zaxcom.com/|title=Zaxcom|website=zaxcom.com}}</ref> HHB Communications Ltd,<ref>{{cite web|url=https://www.hhb.co.uk/|title=- HHB|website=www.hhb.co.uk}}</ref> [[Fostex]], Nagra, Aaton,<ref>{{Cite web|url=http://aaton.com|title=Aaton Digital|website=aaton.com}}</ref> and [[TASCAM]] all use BWF as their preferred format.

===Lossless compressed audio format===
A lossless compressed audio format stores data in less space without losing any information. The original, uncompressed data can be recreated from the compressed version.

Uncompressed audio formats encode both sound and silence with the same number of bits per unit of time. Encoding an uncompressed minute of absolute silence produces a file of the same size as encoding an uncompressed minute of music. In a lossless compressed format, however, the music would occupy a smaller file than an uncompressed format and the silence would take up [[Silence compression|almost no space]] at all.

Lossless compression formats include [[FLAC]], [[WavPack]], [[Monkey's Audio]], [[Apple Lossless Audio Codec|ALAC]] (Apple Lossless). They provide a compression ratio of about 2:1 (i.e. their files take up half the space of PCM). Development in lossless compression formats aims to reduce processing time while maintaining a good compression ratio.

===Lossy compressed audio format===
Lossy audio format enables even greater reductions in file size by removing some of the audio information and simplifying the data. This, of course, results in a reduction in audio quality, but a variety of techniques are used, mainly by exploiting [[psychoacoustics]], to remove the parts of the sound that have the least effect on perceived quality, and to minimize the amount of audible noise added during the process. The popular [[MP3|MP3 format]] is probably the best-known example, but the [[AAC format]] found on the iTunes Music Store is also common. Most formats offer a range of degrees of compression, generally measured in [[bit rate]]. The lower the rate, the smaller the file and the more significant the quality loss.

==List of formats==
{{see also|Comparison of audio coding formats|List of codecs}}

{| class="wikitable sortable" border="1"
|-
! scope="col" | File Extension
! scope="col" | Creation Company
! scope="col" class="unsortable" | Description
|-
| <code>[[.3gp]]</code> ||  || Multimedia container format can contain proprietary formats as [[Adaptive Multi-Rate audio codec|AMR]], [[AMR-WB]] or [[AMR-WB+]], but also some open formats
|-
| <code>[[Audible (service)#Quality|.aa]]</code> || [[Audible (store)|Audible]] ([[Amazon (company)|Amazon]]) || A low-bitrate [[audiobook]] container format with [[Digital rights management|DRM]], containing audio encoded as either [[MP3]] or the [[ACELP]] speech codec.
|-
| <code>[[Advanced Audio Coding|.aac]]</code> ||   || The Advanced Audio Coding format is based on the [[MPEG-2]] and [[MPEG-4]] standards. AAC files are usually [[ADTS]] or [[Advanced Audio Coding|ADIF]] containers.
|-
| <code>[[Audible (service)#Quality|.aax]]</code> || [[Audible (store)|Audible]] ([[Amazon (company)|Amazon]]) || An [[Audiobook]] format, which is a variable-bitrate (allowing high quality) [[MPEG-4 Part 14#Filename extensions|M4B]] file encrypted with [[Digital rights management|DRM]]. MPB contains [[Advanced Audio Coding|AAC]] or [[Apple Lossless Audio Codec|ALAC]] encoded audio in an [[MPEG-4]] container. (More details below.)
|-
| <code>[[ACT (audio format)|.act]]</code> ||  || ACT is a lossy ADPCM 8&nbsp;kbit/s compressed audio format recorded by most Chinese MP3 and MP4 players with a recording function, and voice recorders
|-
| <code>[[.aiff]]</code> || [[Apple Inc.|Apple]] || A standard uncompressed CD-quality, audio file format used by Apple. Established 3 years prior to Microsoft's uncompressed version [[wav]].
|-
| <code>[[Apple Lossless|.alac]]</code> || [[Apple Inc.|Apple]] || An audio coding format developed by Apple Inc. for lossless data compression of digital music.
|-
| <code>[[.amr]]</code> ||  || AMR-NB audio, used primarily for speech.
|-
| <code>[[.ape]]</code> ||  Matthew T. Ashland || Monkey's Audio lossless audio compression format.
|-
| <code>[[Au file format|.au]]</code> || [[Sun Microsystems]] || The standard audio file format used by [[Sun Microsystems|Sun]], [[Unix]] and [[Java (Sun)|Java]]. The audio in au files can be [[PCM]] or compressed with the [[μ-law]], [[a-law]] or [[G.729]] codecs.
|-
| <code>[[.awb]]</code> ||  || AMR-WB audio, used primarily for speech, same as the [[ITU-T]]'s G.722.2 specification.
|-
| <code>[[Digital Speech Standard|.dss]]</code> || [[Olympus Corporation|Olympus]] || DSS files are an [[Olympus Corporation|Olympus]] proprietary format. DSS files use a high compression rate, which reduces the file size and allows files to be copied and transferred quickly.<ref>{{cite web |url= https://audiosupport.omsystem.com/en/miscellaneous/1162-dss-ds2-file-formats/ |title= The Digital Speech Standard (DSS & DSS Pro) |author=<!--Not stated--> |date=August 11, 2020 |website=ReviverSoft |access-date=November 14, 2023}}</ref> It allows additional data to be held in the file header.
|-
| <code>.dvf</code> || [[Sony]] || A Sony proprietary format for compressed voice files; commonly used by Sony dictation recorders.
|-
| <code>[[.flac]]</code> ||  || A file format for the Free Lossless Audio Codec, an open-source lossless compression codec.
|-
| <code>[[GSM-FR|.gsm]]</code> ||  || Designed for telephony use in Europe, GSM is used to store telephone voice messages and conversations. With a bitrate of 13&nbsp;kbit/s, GSM files can compress and encode audio at telephone quality.<ref>{{cite web |url= https://fileexpert.net/gis/gsm |title= What's an .GSM file? |author= 
Andrea Teafancy |date= October 12, 2023 |website=FileExpert.net |access-date=November 14, 2023}}</ref> Note that WAV files can also be encoded with the GSM codec.
|-
| <code>.iklax</code> || iKlax || An iKlax Media proprietary format, the iKlax format is a multi-track digital audio format allowing various actions on musical data, for instance on mixing and volumes arrangements.
|-
| <code>.ivs</code> || 3D Solar UK Ltd || A proprietary version with [[Digital rights management|DRM]] developed by 3D Solar UK Ltd for use in music downloaded from their Tronme Music Store and interactive music and video player.
|-
| <code>[[MPEG-4 Part 14#.MP4 versus .M4A|.m4a]]</code> ||  || An [[Advanced Audio Coding|AAC]] or [[Apple Lossless Audio Codec|ALAC]] encoded audio file in an [[MPEG-4]] container. In Apple's [[iTunes]] Music Store, M4A is used to represent a downloaded music file that is unprotected.
|-
| <code>[[MPEG-4 Part 14#Filename extensions|.m4b]]</code> ||   || An [[Audiobook]] / [[podcast]] extension with [[Advanced Audio Coding|AAC]] or [[Apple Lossless Audio Codec|ALAC]] encoded audio in an [[MPEG-4]] container. Both M4A and M4B formats can contain metadata including chapter markers, images, and hyperlinks, but M4B allows "bookmarks" (remembering the last listening spot), whereas M4A does not.<ref>{{cite web|url=https://www.lifewire.com/what-is-m4b-format-2438562|title=What is the M4b Format?|first1=Mark Harris Brings music|last1=expertise|first2=Including a Background as a Music|last2=Producer|last3=composer|first4=To Digital Music|last4=Articles|website=Lifewire}}</ref>
|-
| <code>[[.m4p]]</code> || [[Apple Inc.|Apple]] || A version of AAC with proprietary [[Digital rights management|DRM]] developed by Apple for use in music downloaded from their [[iTunes]] Music Store and their music streaming service known as [[Apple Music]].
|-
| <code>.mmf</code> || [[Yamaha Corporation|Yamaha]], [[Samsung]] || A Samsung audio format that is used in ringtones. Developed by Yamaha (SMAF stands for "Synthetic music Mobile Application Format", and is a multimedia data format invented by the Yamaha Corporation, .mmf file format).
|-
| <code>.movpkg</code> || [[Apple Inc.|Apple]] || An Apple audio format primarily used for Lossless and Hi-Res audio files through Apple Music. Also used for storing Apple TV videos.
|-
|<code>[[.mp1]]</code>
|
|MPEG-1 Layer I Audio
|-
|<code>[[.mp2]]</code>
|
|MPEG-1/MPEG-2 Layer II Audio
|-
| <code>[[.mp3]]</code> || || MPEG-1/MPEG-2 Layer III Audio
|-
| <code>[[.mpc]]</code> ||  || Musepack or MPC (formerly known as MPEGplus, MPEG+ or MP+) is an open source lossy audio codec, specifically optimized for [[Transparency (data compression)|transparent]] compression of stereo audio at bitrates of 160–180&nbsp;kbit/s.
|-
| <code>.msv</code> || [[Sony]] || A Sony proprietary format for Memory Stick compressed voice files.
|-
| <code>.nmf</code>
|NICE
|[[NICE Ltd.|NICE]] Media Player audio file
|-
| <code>[[Ogg|.ogg, .oga, .mogg]]</code> || [[Xiph.Org Foundation]] || A free, open source container format supporting a variety of formats, the most popular of which is the audio format Vorbis. Vorbis offers compression similar to MP3 but is less popular. Mogg, the "Multi-Track-Single-Logical-Stream Ogg-Vorbis", is the multi-channel or multi-track Ogg file format.
|-
| <code>[[.opus]]</code> || [[Internet Engineering Task Force]] || A lossy audio compression format developed by the Internet Engineering Task Force (IETF) and made especially suitable for interactive real-time applications over the Internet. As an open format standardised through RFC 6716, a reference implementation is provided under the 3-clause BSD license.
|-
| <code>[[RealAudio|.ra, .rm]]</code> || [[RealNetworks]] || A [[RealAudio]] format designed for streaming audio over the Internet. The <code>.ra</code> format allows files to be stored in a self-contained fashion on a computer, with all of the audio data contained inside the file itself.
|-
| <code>[[raw audio format|.raw]]</code> ||  || A raw file can contain audio in any format but is usually used with PCM audio data. It is rarely used except for technical tests.
|-
| <code>[[RF64|.rf64]]</code> ||  || One successor to the Wav format, overcoming the 4GiB size limitation.
|-
| <code>[[Linear PCM|.sln]]</code> ||  || Signed Linear PCM format used by [[Asterisk (PBX)|Asterisk]]. Prior to v.10 the standard formats were 16-bit Signed Linear PCM sampled at 8&nbsp;kHz and at 16&nbsp;kHz. With v.10 many more sampling rates were added.<ref>{{cite web|url=https://wiki.asterisk.org/wiki/display/AST/Asterisk+10+Codecs+and+Audio+Formats|title=Asterisk 10 Codecs and Audio Formats - Asterisk Project - Asterisk Project Wiki|website=wiki.asterisk.org}}</ref>
|-
| <code>.tta</code> ||  || The True Audio, real-time lossless audio codec.
|-
| <code>[[Creative Voice file|.voc]]</code> || [[Creative Technology]] || The file format consists of a 26-byte header and a series of subsequent data blocks containing the audio information
|-
| <code>[[VOX (file format)|.vox]]</code> ||  || The vox format most commonly uses the Dialogic [[ADPCM]] (Adaptive Differential Pulse Code Modulation) codec. Similar to other ADPCM formats, it compresses to 4-bits. Vox format files are similar to wave files except that the vox files contain no information about the file itself so the codec sample rate and number of channels must first be specified in order to play a vox file.
|-
| <code>[[.wav]]</code> ||  [[IBM]] and [[Microsoft]]|| Standard audio file container format used mainly in [[Windows]] PCs. Commonly used for storing uncompressed ([[PCM]]), CD-quality sound files, which means that they can be large in size—around 10&nbsp;MB per minute. Wave files can also contain data encoded with a variety of (lossy) codecs to reduce the file size (for example the GSM or MP3 formats). Wav files use a [[Resource Interchange File Format|RIFF]] structure.
|-
| <code>[[Windows Media Audio|.wma]]</code> || [[Microsoft]] || Windows Media Audio format, created by Microsoft. Designed with [[Digital rights management|DRM]] abilities for copy protection.
|-
| <code>[[.wv]]</code> ||  || Format for wavpack files.
|-
| <code>[[.webm]]</code> || || [[Royalty-free]] format created for [[HTML video]].
|-
| <code>[[8SVX|.8svx]]</code> || [[Electronic Arts]] || The IFF-8SVX format for 8-bit sound samples, created by Electronic Arts in 1984 at the birth of the Amiga.
|-
| <code>[[Red Book (audio CD standard)|.cda]]</code> ||  || Format for cda files for Radio.

|}

== See also ==
* [[Video file format]]
* [[Audio compression (data)]]
* [[Comparison of audio coding formats]]
* [[Comparison of video container formats]]
* [[Comparison of video codecs]]
* [[List of open-source audio codecs]]
* [[Timeline of audio formats]]

==References==
{{reflist}}

{{DEFAULTSORT:Audio File Format}}
[[Category:Digital container formats]]
[[Category:Audio file formats| ]]