mpg123's Assembly code is optimized with SIMDinstructions to improve the performance of the iDCT part of the MPEG decoding.
mpg123's decoding library, libmpg123 is used by DeaDBeeF, Audacious, XMMS and Winamp (version 5.8)[2] for MP3 playback and can be used in Winamp before version 5.8 via a plugin.[3]
The license for the last release (0.59r / 19 June 1999) from the original authors included restrictive (non-commercial, no-derivative) terms, although the source code was available. This led to the creation of mpg321, a similar program (based on MAD) licensed under the GPLv2.[4]
Official development of mpg123 and its library mpglib stalled, and serious security holes emerged.[5][6] Patches were applied downstream for packages provided by various Linux and BSD operating systems.
In 2006, a new maintainer started work towards the release of a new official mpg123 package. After several security rollup releases in the 0.6.x series, version 1.0 was released in 2007 under the LGPLv2.1, with libmpg123 as a replacement for mpglib.
