Understanding Music Formats

Audio formats are the file types used to store audio data to a computer system. The most common file formats are MP3 (MPEG Layer-3), WMA (Windows Media Audio Format) and AAC (Advanced Audio Coding) but it is important to understand that certain formats can be restricted to Mac or Windows based operating systems.

This section describes the different types of open and proprietary music formats available:

Open file formats

gsm – designed for telephony 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

mmf - a Samsung audio format that is used in ringtones.

Proprietary formats

mp3 – 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.

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.

IVS – A proprietary version with Digital Rights Management developed by 3D Solar UK Ltd for use in music downloaded from their Tronme Music Store and interactive music and video player.

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.

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

mxp4 – a Musinaut proprietary format allowing play of different versions (or skins) of the same song. It allows various interactivity scenarios between the artist and the end user.

3gp - multimedia container format can contain proprietary formats as AMR, AMR-WB or AMR-WB+, but also some open formats

amr - AMR-NB audio, used primarily for speech

awb - AMR-WB audio, used primarily for speech

Referenced from Wikipedia.

Music Formats