XMMS2 is a redesign of the XMMS music player. It features a client-server model, allowing multiple (even simultaneous!) user interfaces, both textual and graphical. All common audio formats are supported using plug-ins. On top of this, there is a flexible media library to organize your music.
This package enables decoding of data inside of mp4 containers for XMMS2. Together with xmms2-plugin-faad it's possible to decode .mp4 files. Combined with xmms2-plugin-avcodec you can decode ALAC files.