FluidSynth is a real-time software synthesizer based on the SoundFont 2
specifications. It is a "software synthesizer". FluidSynth can read MIDI
events from the MIDI input device and render them to the audio device.
It can also play MIDI files.

Note: FluidSynth was previously called IIWU Synth.

WWW: http://www.fluidsynth.org/