It is important to distinguish between the audio coding format, the container containing the 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 coder), a multimedia container format (as Matroska or 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, AIFF, AU or raw header-less PCM; Note wav can alternatively use compression.
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 APIs and D/A converter hardware. Although LPCM can be stored on a computer as a raw audio format, it is usually stored in a .wav file on Windows or in a .aiff 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 sample rate, bit depth, endianness and number of channels. 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 the European Broadcasting Union as a successor to WAV. Among other enhancements, BWF allows more robust metadata to be stored in the file. See 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,[1] Sound Devices,[2] Zaxcom,[3] HHB Communications Ltd,[4]Fostex, Nagra, Aaton,[5] 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 almost no space at all.
Lossless compression formats include FLAC, 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 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 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.
An Audiobook format, which is a variable-bitrate (allowing high quality) M4B file encrypted with DRM. MPB contains AAC or ALAC encoded audio in an MPEG-4 container. (More details below.)
DSS files are an Olympus proprietary format. DSS files use a high compression rate, which reduces the file size and allows files to be copied and transferred quickly.[6] It allows additional data to be held in the file header.
Designed for telephony use in Europe, GSM is used to store telephone voice messages and conversations. With a bitrate of 13 kbit/s, GSM files can compress and encode audio at telephone quality.[7] Note that WAV files can also be encoded with the GSM codec.
.iklax
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.
.ivs
3D Solar UK Ltd
A proprietary version with DRM developed by 3D Solar UK Ltd for use in music downloaded from their Tronme Music Store and interactive music and video player.
An audio-only MPEG-4 file, used by Apple for unprotected music downloaded from their iTunes Music Store. Audio within the m4a file is typically encoded with AAC, although lossless ALAC may also be used.
An Audiobook / podcast extension with AAC or 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.[8]
A version of AAC with proprietary DRM developed by Apple for use in music downloaded from their iTunes Music Store and their music streaming service known as Apple Music.
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).
Musepack or MPC (formerly known as MPEGplus, MPEG+ or MP+) is an open source lossy audio codec, specifically optimized for transparent compression of stereo audio at bitrates of 160–180 kbit/s.
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.
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.
A RealAudio 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.
Signed Linear PCM format used by Asterisk. Prior to v.10 the standard formats were 16-bit Signed Linear PCM sampled at 8 kHz and at 16 kHz. With v.10 many more sampling rates were added.[9]
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.
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 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 RIFF structure.
^Andrea Teafancy (October 12, 2023). "What's an .GSM file?". FileExpert.net. Retrieved November 14, 2023.
^expertise, Mark Harris Brings music; Producer, Including a Background as a Music; composer; Articles, To Digital Music. "What is the M4b Format?". Lifewire.
