The following tables compare general and technical information for a variety of audio codecs. For listening tests comparing the perceived audio quality of audio codecs, see the article Codec listening test.
First public release date is first of either specification publishing or source releasing, or in the case of closed-specification, closed-source codecs, is the date of first binary releasing. Many developing codecs have pre-releases consisting of pre-1.0 versions and perhaps 1.0 release candidates (RCs), although 1.0 may not necessarily be the release version.
Latest stable version is that of specification or reference tools.
If there happens to be OSI licensed software available for a particular codec, this does not necessarily permit one to use said codec free of charge. Likewise, if there is only proprietary licensed software available for a particular codec, one might be able to use the codec free of charge.
MP3 licence and patent status: The MP3 format is patented and therefore subject to license (expires latest: 2017 but US patents after Dec 2012 may be invalid). However with multiple contenders for the patent, it is far from certain in the market who is the patent holder with the right to set pricing and royalties. A sample of prices for one patent-holder is available. In practice, there is a wide range of MP3 authoring software and MP3 encoding worldwide is often performed on a private basis and unpaid, with patent rights unenforced against end users. See MP3#Licensing and patent issues.
^ ab The ffmpeg project has reverse engineered some codecs of the RealAudio and Windows Media Audio (DivX Audio v1 and DivX Audio v2) formats. This enables their use on any POSIX compatible system.
^ MPEG 2 AAC was limited to a 96 kHz sampling rate, however, with MPEG 4 AAC, a later version part of the MPEG 4 specification, the maximum sampling rate has been increased to 192 kHz.
