Hydrogen is a simple real-time Drum machine/sequencer. It features a graphical user interface based on Qt, a sample-based audio engine, Jack/ALSA/OSS/PortAudio and Export to disk audio drivers, ALSA MIDI input, ability to import/export XML-based song and drumkit files, 192 ticks per pattern, 16 voices with volume, mute, solo, ADSR, and pan capabilities, and import of samples in wave, au, and aiff format.
FluidSynth is a real-time software synthesizer based on the SoundFont 2 specifications. It can read MIDI events from MIDI input devices or files and render them to an audio device using SoundFont instrument banks. It can also play MIDI files. Other features include real time effect control and a powerful API for embedding FluidSynth in other programs.
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.
jMusic provides a library of classes for generating and manipulating music, and is a solid framework for computer assisted composition in Java. jMusic supports composers by providing a music data structure based upon note/sound events, and methods for working with that musical data. jMusic can read and write MIDI files, audio files, and its own .jm files. jMusic is designed to be extendible, encouraging you to build upon the functionality of jMusic by programming in Java to create your own music composition tools.
jMax is a visual programming environment for building interactive real-time musical and multimedia applications by allowing the user to interactively design dataflow circuits. The basic data types that can go through are integers, symbols, lists, etc. It is an event-driven system and has been used for MIDI processing. A second part of the system (DSP) allows a continuous signal to flow through a circuit, which is most useful for PCM sound (ie. microphone, sound files, etc.). The system is extensible by using shared libraries, you may add data processor types, data types, GUI elements, device types, and more. Data processors may also be designed as circuits and reused.
Sfront compiles MPEG 4 Structured Audio (MP4-SA) programs into efficient C programs that generate audio when executed. MP4-SA is a standard for normative algorithmic sound, which combines an audio signal processing language (SAOL) with score languages (MIDI and SASL). Under Mac OS X and Linux, sfront supports real-time, low-latency audio input/output and MIDI input. Under Mac OS X, sfront supports the creation of AudioUnit plug-ins. The documentation includes a book about SAOL programming.
WaveSurfer is a sound visualization/manipulation tool for novice and advanced users, with a simple and intuitive user interface. It can be adapted to different tasks, such as speech research and education, speech/sound analysis, and sound annotation/transcription. You can also make more advanced/specialized applications by extending it with custom plugins or embed WaveSurfer components in other applications. Its flexible interface handles many different file formats, and it runs on many flavors of Windows and Unix. It also supports encoding and Unicode with unlimited file size, and more.
Csound is a powerful and yet easy to use musical synthesis package. Csound was constructed in the tradition of so-called music-N languages, among which the best-known is Music V. It consists of an orchestra- and score-driven executable, written in C for portability. Since Csound is a computational language, it is highly flexible and efficient; complexity is gained only at the expense of computation power. Basically, Csound reads some files and creates the result as a sound file on disk or, on faster machines, in real time through a DAC.
CLAM is a multiplatform software framework for research and application development for the Audio and Music domains. It offers a conceptual model for building systems as well as tools for the analysis, synthesis, and transformation of audio signals using high level representation (notes, spectral peaks, etc.). It also provides multiplatform system abstraction and tools for audio and MIDI file handling, device handling, GUI and XML support, and more. It has proper Linux audio architecture integration (Ladspa, Alsa, OSC, Jack, VST, etc.) and rapid graphical prototyping both for the processing core and the user interface (Qt designer integration).