din is a software musical instrument and audio synthesizer. Bezier curves are used to draw and sculpt waveforms, create gating and modulation (FM and AM) patterns, and create delay feedback and volume patterns. You can also create an unlimited number of drones and sculpt their waveforms. It uses JACK to output audio, and supports MIDI, OSC and IRC bot for input. din can be extended and customized with Tcl scripts.
orDrumbox is a fully-featured drum machine and audio sequencer that is pattern oriented, has an automatic composer, automatic sound assignations, custom drum kits, loop support, and the ability to import and export songs. Its main features are a pattern seqencer, a drumkit editor, a piano roll, a step sequencer, sound generation, soft synth, and the ability to import and export MIDI files and Wave files.
Faust AUdio STreams is an expressive functional programming language for realtime audio signal processing. The Faust compiler translates DSP specifications into efficient C++ code. A variety of platforms and plugin formats are supported. A single Faust specification can be used to easily generate JACK and ALSA applications, as well as LADSPA, MAX/MSP, PD, Q, SC, and VST plugins. In addition to C++ code, the Faust compiler can also generate SVG block-diagram representations as well as XML descriptions.
Qsynth is a GUI front-end application for Fluidsynth. Fluidsynth is a command-line software synthesizer based on the Soundfont specification. Qsynth was built with the Qt4 toolkit using Qt Designer. Eventually it may evolve into a softsynth management application that allows the user to control and manage a variety of command line softsynths, but it currently just wraps the excellent Fluidsynth program.
TerminatorX is a realtime audio synthesizer that allows you to "scratch" on digitally sampled audio data (*.wav, *.au, *.mp3, etc.) the way hiphop-DJs scratch on vinyl records. It features multiple turntables, realtime effects (built-in as well as LADSPA plugin effects), a sequencer, and an easy-to-use GTK+ GUI.