LAME (LAME Ain't an MP3 Encoder) is a research project for learning about and improving MP3 encoding technology. LAME includes an MP3 encoding library, a simple frontend application, and other tools for sound analysis, as well as convenience tools. Please note that any commercial use (including distributing the LAME encoding engine in a free encoder) may require a patent license from Thomson Multimedia.
MPy3 is a full-featured, modular, configurable MP3 player system aimed at jukeboxes or car MP3 systems. It can play MP3s via rxaudio or mpg123, take input from a keyboard (tty), LIRC, or joystick. It does output through a CrystalFontz LCD directly, or through any LCD that LCDProc supports, or even through X. It features playlist support and support for controlling the mixer (using aumix). All of the inputs, outputs, and other functions are controlled via a number of modular libraries which can be used in other projects as well.
rioutil is a utility designed for the use of interfacing with Sonic Blue/dnna's third, fourth, and fifth generations of flash MP3 players (Rio 600/800/900/S-Series/Riot/Cali/Chiba/Fuse and Nike psa[play). On many players, it goes beyond the packaged software by providing downloading.
SDLucid is a C++ wrapper library for the SDL media library. It aims to not only be a wrapper, but to also offer a cleaner interface than the original SDL, as well as increased functionality. This additional functionality includes fonts, PNG loading, graphical primitives, built-in mixing, mod playing, and MP3 decoding. SDLucid follows naming conventions, approximating those of the Standard Template Library.