Karlheinz Essl

Portrait KHE

Music Software


This page informs about several computer programs that has been developed by Karlheinz Essl as tools for composition, live performance and sound design. Based on concepts of realtime and algorithmic composition - a field of research in which Essl is working since 1985 - they are tailored towards the needs of musicians who are interested in generative music, randomness and indeterminacy.



  RTC Real Time Composition Library - RTC-lib (copyleft 1992-2014) NEW
software library for algorithmic composition - open source

A collection of patches ("abstractions" and "externals") for Max/MSP/Jitter and Pd which offer the possibility to experiment with compositional techniques including serial procedures, permutations and controlled randomness.

  • version 6.0 (released 31 Jan 2014) - Freeware for Max5 and Max6 running Intel Processors under MacOS X 10.6 or later
  • version 5.0 (released 10 Jan 2010) - Freeware for Max/MSP 5.0 running on PPC or Intel Processors under MacOS X 10.4 or later
  • version 4.7 (released 2 Apr 2008) - Freeware for Max/MSP 4.6 running on PPC or Intel Processors under MacOS X 10.4 or later
  • version 4.1.1 (released 5 Dec 2007) - Freeware for Max/MSP 4.5 or higher running under Windows XP
  • version 4.0.2 (released 26 Jan 2004) - Freeware for Max/MSP 4.5 and MacOS X 10.2 (or higher); PPC processors only
  • version 1.0 (released 26 Nov 2006) - Freeware for Pd (Pure Data)


  AM Amazing Maze (© 1993-2014) NEW
interactive realtime composition for sampled sound particles

Amazing Maze is a infinite realtime composition that creates an astounding sonic cosmos by manipulating instrumental sound particles in time and space. It takes advantage of composition algorithms that have been developed by Karlheinz Essl since the 1985 years. The generation process can be conducted by an automatism or by user interaction.

  • version 3.0 (released 7 Feb 2014) - Freeware for Windows XP
  • version 3.0 (released 24 Jan 2014) - Freeware for Apple MacOS X


  fLOW fLOW (© 1998-2013) NEW
ambient soundscape generator

fLOW is an audio computer program running on Apple Macintosh machines. It generates an ever-changing and never repeating soundscape in real time that fills the space with flooding sounds that resemble - metaphorically - the timbres of water, fire, earth, and air. This ambient sound scape generator adjusts itself through various parameters and controllers that are represented in real time on your screen. Feed your own sounds into the system and listen what the algorithms are composing. The system parameters can be accessed either by the mouse or with an attached MIDI controller. Use your own VST or AU plugIns for extended sound processing. And finally, the result can be recorded as a sound file.

  • version 4.0 (released 11 May 2013) - Shareware for Apple Macintosh computers (Mac OS X 10.6 or higher)


  RP REplay PLAYer (© 2000-2013) NEW
generative sound file shredder

REplay PLAYer is a computer program that deconstructs a given sound file and recomposes it by using realtime composition algorithms. It can be used as a tool to generate an infinite and every-changing sonic stream from a single sound file for artistic, compositional or mere recreational purposes. It can also be regarded as a computer based instrument for live performances, as an interactive sound installation or a generator for ambient music.

  • version 4.0 (released 7 May 2013) - Shareware for Apple Macintosh computers (Mac OS X 10.6 or higher)


  FontanaMixer FontanaMixer (© 2004-2012) NEW
generative sound environment based on John Cage's Fontana Mix (1958)

FontanaMixer is a generative sound environment based on John Cage's "Fontana Mix" (1958). The original concept of the piece uses a graphical random generator that is supplied with the score. This new version, however, uses realtime sound generation and produces completely unpredictable sonic results which are reflecting Cage's ideas of indeterminacy, chance, and silence.

  • version 2.0 (released 3 Feb 2012) - Freeware for Apple Macintosh computers


  WUW WebernUhrWerk (© 2005-2011)
generative music generator

A computer program that automatically composes generative Carillon music based on the twelve-tone row of Anton Webern's last composition which he was unable to finish due to his sudden and unexpected death on 15 Sep 1945 when he was accidentially shot dead by an American GI. The program simulates a Carillon that plays a short musical phrase every 15 minutes which never repeats itself.

  • version 2.3 - Universal Binary (released 12 Jan 2011) - Freeware for Apple Macintosh computers (PPC or Intel)
  • version 2.1 beta (released 10 Sep 2006) - Freeware for Intel PCs (Windows 2000 / Windows XP)


  LS Lexikon-Sonate (© 1992-2010)
algorithmic music generator

Lexikon-Sonate is an interactive realtime composition environment for musical composition and live performances. It takes advantage of composition algorithms that have been developed by Karlheinz Essl since the 1985 years. With this algorithmic music generator on can easily create fascinating and complex musical structures on the fly. Lexikon-Sonate is an infinite music installation that can run on a computer for years without repeating itself. It can also be used as a computer instrument for live performances.

  • version 4.0.1 - Universal Binary (released 5 Dec 2010) - Freeware for Apple Macintosh computers (PPC or Intel)


  more or less more or less (© 1999-2007)
random-generated playing instructions for musical improvisation

more or less is an computer-driven realtime composition where the musicians do not reproduce parts of a fixed score. Instead of executing a pre-fabricated text from note sheets, they are viewing computer monitors which display random-generated playing instructions. During the performance of the piece the musicians can make queries to their computers asking for playing instructions whenever they feel a necessity for it. Furthermore, a random-generated Haiku is created whenever a musician receives a new instruction from the computer. This is a three-liner providing a puzzle which has to be "solved" by the musicians and which will influence the interpretation of the required structure to a great extend.

  • version 1.3 - Universal Binary (released 14 Jan 2007) - Freeware for Apple Macintosh computers (PPC or Intel)


  SEELEWASCHEN SEELEWASCHEN (© 2003-2006)
generative sound environment

SEELEWASCHEN is a generative sound environment which was originally composed by Karlheinz Essl for an outdoor light installation by the German artist Rainer Gottemeier. Using the sound of one single bell stroke as its basic material, the piece unfolds a rich sonic cosmos by a computer program. Taking advantage compositional algorithms that have been developed by Karlheinz Essl since the early 1980ies, the piece is generated in realtime. It can be perceived as a sonic organism which might serve as a source for inspiration and meditation, running forever and ever...

  • version 1.2 - Universal Binary (released 20 Oct 2006) - Freeware for Apple Macintosh computers (PPC or Intel)


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Updated: 7 Feb 2014