mpg123 is a fast MPEG Audio Layer 1 / 2 / 3 decoding library and terminal playing utility. It uses floats or integer arithmetics with any available instruction set extension (3DNow, SSE, ARM) for efficiency.
QMMP is an Qt-based audio-player. The user interface is similar to Winamp or XMMS, which compatible skins can be used of. It supports a plethora of audio formats, like MP3, Ogg Vorbis/Opus, FLAC, Musepack, WavePack, MOD files, AAC, Audio CDs, WMA and other ffmpeg-supported encodings, PCM, MIDI, SID, and Chiptune files. It provides DSP plugins, lyrics downloading, equalizers and visualizers, supports common audio APIs and sinks, and is cross-platform.
Lollypop is a visual music collection browser and player for Gnome. It supports MP3/MP4, FLAC and OGG Vorbis, presents a genre and album cover browser, sorting and searching by genre and artist, art/cover downloading, a playing queue and different replay modes.
MP3Blaster is a text console based program for playing mainly mp3 audio files. It is very interactive, and has a great list of features. Its playlist can be divided in albums or categories (called 'groups'), which allows for very sophisticated playback orders.
Siren is a text-based audio player for UNIX-like operating systems. Supported file formats include Ogg Vorbis, MP3, Opus, FLAC, AAC, WavPack, WAVE and AIFF. Playback is possible through sndio, PulseAudio, ALSA, OSS, Sun audio, PortAudio and libao. Siren is known to run on OpenBSD, NetBSD, FreeBSD, Linux and OS X.
The program gst123 is designed to be a more flexible command line player in the spirit of ogg123 and mpg123, based on GStreamer. It plays all file formats supported by GStreamer, so if you have audio/video collections which contain different file formats, like flac, ogg and mp3, you can use gst123 to play all your audio/video files.
Oggify is a command-line tool to convert between different audio formats. It's foremost intended to manage OGG Vorbis based collections, but also supports FLAC, or MP3 for older players, ALAC and MP4 on Mac OS X.
Potamus is an audio player, very lightweight and GTK-based, derived from xhippo. It doesn't require a complex database, but just utilizes the filesystem as-is for music collections. It supports MP3, FLAC, Ogg Vorbis, Opus and other ModPlug/FFMpeg/audiofile-supported formats. Potamus supports OSS and ALSA or JACK for playback.
mp3splt breaks up MP3, OGG Vorbis and FLAC audio files without decoding. It doesn't require pre-defined timestamps but CUE or CDDB meta info, or by detecting album or stream audio silence breaks. It's a command-line tool, but a Gtk+ interface is also available.
Nightingale is a cross-platform and extensible media player. It's derived from the Songbird media player (to continue Linux support) with its GUI based on Mozilla XULRunner and GStreamer used for audio playback. Songbird addons can still be used, it supports MP3, AAC, Ogg Vorbis, FLAC, WMA files, and MS or Apple DRM-covered files. It adds MP3/RSS playlists, custom mixes, scanning local media directories, a minimized user interface, Last.fm integration, meta data editing, iTunes import, cus