Anaudio file format is afile format for storingdigital audio data on acomputer system. Thebit layout of the audio data (excludingmetadata) is called theaudio coding format and can be uncompressed, orcompressed to reduce the file size, often usinglossy compression. The data can be a rawbitstream in an audio coding format, but it is usually embedded in acontainer format or an audio data format with defined storage layer.

It is important to distinguish between theaudio coding format, thecontainer containing theraw audio data, and anaudio 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 anaudio coder), a multimedia container format (asMatroska orAVI) may support multiple types of audio and video data.

There are three major groups of audio file formats:

• Uncompressed audio formats, such asWAV,AIFF,AU orraw header-lessPCM; Note wav can alternatively use compression.
• Formats withlossless compression, such asFLAC,Monkey's Audio (filename extension.ape),WavPack (filename extension.wv), TTA,ATRAC Advanced Lossless,ALAC,MPEG-4 SLS,MPEG-4 ALS,MPEG-4 DST,Windows Media Audio Lossless (WMA Lossless), andShorten (SHN).
• Formats withlossy compression, such asOpus,MP3,Vorbis,Musepack,AAC,ATRAC andWindows Media Audio Lossy (WMA lossy).

One major uncompressed audio format,LPCM, is the same variety of PCM as used inCompact Disc Digital Audio and is the format most commonly accepted by low level audioAPIs andD/A converter hardware. Although LPCM can be stored on a computer as araw audio format, it is usually stored in a.wav file onWindows or in a.aiff file onmacOS. TheAudio Interchange File Format (AIFF) format is based on theInterchange File Format (IFF), and the WAV format is based on the similarResource 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 particularsample rate,bit depth,endianness and number ofchannels. Since WAV and AIFF are widely supported and can store LPCM, they are suitable file formats for storing and archiving an original recording.

BWF (Broadcast Wave Format) is a standard audio format created by theEuropean Broadcasting Union as a successor to WAV. Among other enhancements, BWF allows more robustmetadata to be stored in the file. SeeEuropean 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 standardizedtimestamp reference which allows for easy synchronization with a separate picture element. Stand-alone, file based, multi-track recorders from AETA,^[1] Sound Devices,^[2] Zaxcom,^[3] HHB Communications Ltd,^[4]Fostex, Nagra, Aaton,^[5] andTASCAM all use BWF as their preferred 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 upalmost no space at all.

Lossless compression formats includeFLAC,WavPack,Monkey's Audio,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 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 exploitingpsychoacoustics, 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 popularMP3 format is probably the best-known example, but theAAC format found on the iTunes Music Store is also common. Most formats offer a range of degrees of compression, generally measured inbit rate. The lower the rate, the smaller the file and the more significant the quality loss.

• 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