It is important to distinguish between a file format and a codec. A codec performs the encoding and decoding of the raw audio data while the data itself is stored in a file with a specific audio file format. Though most audio file formats support only one audio codec, a file format may support multiple codecs, as AVI does.

There are three major groups of audio file formats:

* Uncompressed audio formats, such as WAV, AIFF and AU;
* Formats with lossless compression, such as FLAC, Monkey's Audio (filename extension APE), WavPack (filename extension WV), Shorten, TTA, Apple Lossless and lossless Windows Media Audio (WMA); and
* formats with lossy compression, such as MP3, Vorbis, lossy Windows Media Audio (WMA) and AAC.

Uncompressed audio format

There is one major uncompressed audio format,PCM, which is usually stored as a .wav on Windows or as .aiff on Mac OS. WAV is a flexible file format designed to store more or less any combination of sampling rates or bitrates. This makes it an adequate file format for storing and archiving an original recording. A lossless compressed format would require more processing for the same time recorded, but would be more efficient in terms of space used. WAV, like any other uncompressed format, encodes all sounds, whether they are complex sounds or absolute silence, with the same number of bits per unit of time. As an example, a file containing a minute of playing by a symphonic orchestra would be the same size as a minute of absolute silence if they were both stored in WAV. If the files were encoded with TTA, the first file would be marginally smaller, and the second file taking up almost no space at all. However, to encode the files to TTA would take significantly more time than encoding the files to the WAV format.

The WAV format is based on the RIFF file format, which is similar to the IFF format.

BWF (Broadcast Wave Format) is a standard audio format created by the European Broadcasting Union as a successor to WAV. BWF allows metadata to be stored in the file. See: European Broadcasting Union: Specification of the Broadcast Wave Format — A format for audio data files in broadcasting. EBU Technical document 3285, July 1997. This format is the primary recording format used in many professional Audio Workstations used in the Television and Film industry. Stand-alone file based multi-track recorders from Sound Devices, Zaxcom, HHB USA, Fostex, and Aaton all use BWF as their preferred file format for recording multi-track audio files with SMPTE Time Code reference. This standardized Time Stamp in the Broadcast Wave File allows for easy synchronization with a separate picture element.

Lossless audio formats

Lossless audio formats (such as TTA and FLAC) provide a compression ratio of about 2:1.

Free and open file formats

wav – standard audio file 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 MB per minute of music. It is less well known that wave files can also be encoded with a variety of codecs to reduce the file size (for example the GSM or mp3 codecs). Wav files use a RIFF structure.
ogg – a free, open source container format supporting a variety of codecs, the most popular of which is the audio codec Vorbis. Vorbis offers better compression than MP3 but is less popular.
flac – a lossless compression codec. You can think of lossless compression as like zip but for audio. If you compress a PCM file to flac and then restore it again it will be a perfect copy of the original. (All the other codecs discussed here are lossy which means a small part of the quality is lost). The cost of this losslessness is that the compression ratio is not good. Flac is recommended for archiving PCM files where quality is important (e.g. broadcast or music use).
aiff – the standard audio file format used by Apple. It is like a wav file for the Mac.
raw – a raw file can contain audio in any codec but is usually used with PCM audio data. It is rarely used except for technical tests.
au – the standard audio file format used by Sun, Unix and Java. The audio in au files can be PCM or compressed with the μ-law, a-μlaw or G729 codecs.

Open file formats

gsm – designed for telphony use in Europe, gsm is a very practical format for telephone quality voice. It makes a good compromise between file size and quality. Note that wav files can also be encoded with the gsm codec.
dct – A variable codec format designed for dictation. It has dictation header information and can be encrypted (often required by medical confidentiality laws).
vox – 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.
aac – the Advanced Audio Coding format is based on the MPEG2 and MPEG4 standards. aac files are usually ADTS or ADIF containers.
mp4/m4a – MPEG-4 audio most often AAC but sometimes MP2/MP3

Proprietary formats

mp3 – the MPEG Layer-3 format is the most popular format for downloading and storing music. By eliminating portions of the audio file that are essentially inaudible, mp3 files are compressed to roughly one-tenth the size of an equivalent PCM file while maintaining good audio quality. The mp3 format is recommended for music storage. It is not that good for voice storage. Many people confuse Mp3 as a open format, but it isn't.
wma – the popular Windows Media Audio format owned by Microsoft. Designed with Digital Rights Management (DRM) abilities for copy protection.
atrac (.wav) – the older style Sony ATRAC format. It always has a .wav file extension. To open these files simply install the ATRAC3 drivers.
ra – a Real Audio format designed for streaming audio over the Internet. The .ra 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.
ram – a text file that contains a link to the Internet address where the Real Audio file is stored. The .ram file contains no audio data itself.
dss – Digital Speech Standard files are an Olympus proprietary format. It is a fairly old and poor codec. Prefer gsm or mp3 where the recorder allows. It allows additional data to be held in the file header.
msv – a Sony proprietary format for Memory Stick compressed voice files.
dvf – a Sony proprietary format for compressed voice files; commonly used by Sony dictation recorders.
m4p – A proprietary version of AAC in MP4 with Digital Rights Management developed by Apple for use in music downloaded from their iTunes Music Store.
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Extension File type description
aac file icon.aac Advanced audio coding
aif file icon.aif Audio Interchange File Format sound file
aifc file icon.aifc Audio Interchange File Format sound file with Compression
aiff file icon.aiff Audio Interchange File Format
aifr file icon.aifr Audio Interchange File Format
amr file icon.amr Adaptive Multi-Rate compressed audio
ape file icon.ape Monkey's Audio Lossless Audio Compression Format
asf file icon.asf Advanced Systems format
aufile icon.au Unix audio sound file format
aud file icon.aud DTS sound data stream file format
aud file icon.aud Winamp media file
aup file icon.aup Audacity project file
binfile icon.bin Audio format (short ints, no header)
bwf file icon.bwf Broadcast wave file format
cda file icon.cda CD Audio track
dct file icon.dct Variable codec format designed for dictation
dss file icon.dss Digital Speech Standard File (various Voice Recorders)
dts file icon.dts Digital Surround Audio File Format
dvf file icon.dvf DV Studio Camcorder voice file
esu file icon.esu LokSound Electronic Sound File
eta file icon.eta eTreppid Audio File
flac file icon.flac Audio files encoded by Flac - free lossless audio codec
gsm file icon.gsm Sound (GSM 6.10 prI-ETS 300 036 13kbit/s) (Internet phones)
m4a file icon.m4a MPEG-4 compressed audio file
m4p file icon.m4p iTunes Music Store Audio File
mdi file icon.mdi MIDI-sequention sound
mid file icon.mid MIDI-sequention sound
midi file icon.midi MIDI-sequention sound
mp2 file icon.mp2 Sound file (MPEG-1 Layer II Audio Stream)
mp2a file icon.mp2a Sound file (MPEG-1 Layer II Audio Stream)
mp3 file icon.mp3 Compressed audio, music file
mpc file icon.mpc MusePack Audio file
mpega file icon.mpega MPEG Sound
msv file icon.msv Memory Stick compressed voice files
mus file icon.mus Music file format
mus file icon.mus SCORE Music publishing system music notation
nwc file icon.nwc Noteworthy Composer Song File
nwp file icon.nwp Noteworthy Player file type
ogg file icon.ogg Ogg Vorbis audio file open-source music encoder
psb file icon.psb Pinnacle: Sound Bank file
psm file icon.psm Protracker Studio Module (sound)
psm file icon.psm Sound data for Epic's games
ra file icon.ra RealAudio
ram file icon.ram Real Audio sound
rel file icon.rel Nokia Phone Audio File
sab file icon.sab ALSong Album File
shn file icon.shn Shorten compressed audio file, lossless format but larger than MP3
smf file icon.smf Standard MIDI file format
snd file icon.snd Unix sound file, similar to AU
speex file icon.speex A Free Codec For Free Speech
tta file icon.tta TAU Producer file - TTA Lossless audio codec
vox file icon.vox Dialogic sound
vy3 file icon.vy3 VY3 is Samsung Yepp VY-H350H Digital Voice Recorder format
wav file icon.wav WAVe PCM Sound, standard Windows sound format
wave file icon.wave WAVe PCM sound file
wma file icon.wma Windows Media Audio
wpk file icon.wpk Nero Wave Editor file
wpl file icon.wpl Windows Media Player Playlist
wv file icon.wv WavPack lossless compressed audio file
wvc file icon.wvc WawPack lossless compressed audio file format correction file