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Csound is a domain-specific computer programming language for audio programming. It is called Csound because it is written in C, as opposed to some of its predecessors. It is free software, available under the LGPL-2.1-or-later. Csound was originally written at MIT by
Barry Vercoe Barry Lloyd Vercoe (born 1937) is a New Zealand-born computer scientist A computer scientist is a person who is trained in the academic study of computer science. Computer scientists typically work on the theoretical side of computation, ...
in 1985, based on his earlier system called Music 11, which in its turn followed the MUSIC-N model initiated by Max Mathews at the Bell Labs. Its development continued throughout the 1990s and 2000s, led by John Fitch at the University of Bath. The first documented version 5 release is version 5.01 on March 18, 2006. Many developers have contributed to it, most notably Istvan Varga, Gabriel Maldonado, Robin Whittle, Richard Karpen, Iain McCurdy, Michael Gogins, Matt Ingalls, Steven Yi, Richard Boulanger, Victor Lazzarini and Joachim Heintz. Developed over many years, it currently has nearly 1700 unit generators. One of its greatest strengths is that it is completely modular and extensible by the user. Csound is closely related to the underlying language for the Structured Audio extensions to
MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related tec ...
,
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.


Csound code

Csound takes two specially formatted text files as input. The ''orchestra'' describes the nature of the instruments and the ''score'' describes notes and other parameters along a timeline. Csound processes the instructions in these files and renders an audio file or real-time audio stream as output. The ''orchestra'' and ''score'' files may be unified into a single structured file using
markup language Markup language refers to a text-encoding system consisting of a set of symbols inserted in a text document to control its structure, formatting, or the relationship between its parts. Markup is often used to control the display of the document ...
tags (a CSD file with filename extension .csd). Here is a very simple example of a unified Csound data file which produces a wave file containing a one-second
sine wave A sine wave, sinusoidal wave, or just sinusoid is a curve, mathematical curve defined in terms of the ''sine'' trigonometric function, of which it is the graph of a function, graph. It is a type of continuous wave and also a Smoothness, smooth p ...
tone of 1 kHz at a sample rate of 96 kHz: csound -W -d -o tone.wav sr = 96000 ; Sample rate. kr = 9600 ; Control signal rate. ksmps = 10 ; Samples per control signal. nchnls = 1 ; Number of output channels. instr 1 a1 oscil p4, p5, 1 ; Oscillator: p4 and p5 are the arguments from the score, 1 is the table number. out a1 ; Output. endin f1 0 8192 10 1 ; Table containing a sine wave. Built-in generator 10 produces a sum of sinusoids, here only one. i1 0 1 20000 1000 ; Play one second of one kHz at amplitude 20000. e As with many other programming languages, writing long programs in Csound can be eased by using an
integrated environment A command shell is a command-line interface to interact with and manipulate a computer's operating system. General characteristics Interactive features Background execution Background execution allows a shell to run a command without us ...
for editing, previewing, testing, and
debugging In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve in ...
. The one now officially supported is CsoundQt, and it has many features, such as automatic code insertion, integrated documentation browser, integrated widgets for graphically controlling parameters in realtime, plus a button for playing the code.


Csound 5

Version 5.01 was released on March 18, 2006 – 20 years after csound's first release. Csound 5 is available in binary and source code for Linux, Microsoft Windows and Mac OS X from the SourceForge Csound project. It is much improved and expanded compared to the original software, effectively made into a software library with an API. A variety of front ends have been developed for it. In addition to the basic C API, there are also Python, Java,
Lisp A lisp is a speech impairment in which a person misarticulates sibilants (, , , , , , , ). These misarticulations often result in unclear speech. Types * A frontal lisp occurs when the tongue is placed anterior to the target. Interdental lisping ...
, Tcl and C++ among other bindings, like one from Haskell which allows control of Csound from a purely functional environment. The use of plug-ins allows additional capabilities without modifications to the Csound code, as there is the possibility to write user-defined opcodes as extensions to the original language. LADSPA and DSSI are supported, but
VST VST may refer to: * Vancouver School of Theology, a theological graduate school in British Columbia, Canada * VST, Stockholm Västerås Airport in Sweden (IATA airport code) * Vehicle safety technology * Virtual Studio Technology, Steinberg's stand ...
support has been removed. Real-time performance through MIDI was added in the 1990s. Another addition was the support of FLTK widgets (graphical interface components with sliders, knobs, etc.) for controlling real-time audio, and integration of custom graphical interfaces written in Python.


Csound 6

Csound 6 has been in development since its features were hashed out at the Csound Conference held in 2011 in Hanover. Csound 6 was released in July 2013 and is now available on GitHub. Csound 6 is also available for
Android Android may refer to: Science and technology * Android (robot), a humanoid robot or synthetic organism designed to imitate a human * Android (operating system), Google's mobile operating system ** Bugdroid, a Google mascot sometimes referred to ...
. The major new features of Csound 6 include: * A
bison Bison are large bovines in the genus ''Bison'' (Greek: "wild ox" (bison)) within the tribe Bovini. Two extant and numerous extinct species are recognised. Of the two surviving species, the American bison, ''B. bison'', found only in North Ame ...
/ flex based parser for the Csound language is now standard. It generates an abstract syntax tree that is accessible via the Csound API. The tree can then be compiled to a Csound performance runtime using the API. Therefore, after the tree has been compiled, it can be manipulated by user code before compiling it to a Csound performance runtime. Alternatively, the user could create the entire abstract syntax tree from another language, then compile the tree to a Csound performance runtime. * There is a new built-in multi-dimensional array type. Arrays can be passed to instruments and opcodes. Arithmetic may be performed directly on arrays. * There is a new type system that enables user-defined types to be used in the Csound language. * The orchestra can be re-compiled at any time, or individual instruments can be compiled at any time, during a running performance. This enables true "live coding" in Csound performances. * The Csound API has been rationalized and simplified. * Csound can take advantage of any number of CPUs for concurrent processing during performance. This occurs without any changes to Csound code. This produces substantial speedups of most Csound processing. For example, a piece that renders in 100 seconds with 1 core should render in about 50 seconds with 4 cores. * Csound can compile orchestras and scores directly from strings of text, enabling the use of Csound in environments where writing to the file system is not permitted. * Score events such as notes can be scheduled to sample accurate times, even if synthesis is processed in blocks of samples. * All opcodes that return a single value may be used as functions in the orchestra language. * Audio analysis file formats can be byte-order independent. * A single score statement can contain multiple string parameters. * Most oscillator opcodes will use an internal sine function table if the table number is omitted. * Command-line options can be set programmatically using the Csound API. * Numerous duplicate areas of code within Csound have been rationalized. * An Android app was built which provides user-defined graphical user interfaces and JavaScript-based algorithmic composition using HTML5. The development of Csound 6 was led by
John ffitch John Peter Fitch (also known as John ffitch) is a computer scientist, mathematician and composer, who has worked on relativity, planetary astronomy, computer algebra and Lisp. Alongside Victor Lazzarini and Steven Yi, he is the project leader f ...
, Steven Yi and Victor Lazzarini.


Csound for live performance

Currently only Csound score or note events can be generated in real time (as opposed to instruments, which are only definable at compile time, when csound first starts; in Csound 6 this limitation is removed). The set of sound processors is defined and compiled at load time, but the individual processing objects can be spawned or destroyed in real time, input audio processed in real time, and output generated also in real time. Note events can be triggered based on OSC communications within an instrument instance, spawned by MIDI, or entered to stdin (by typing into a terminal or sending textual statements from another program). The use of Csound 5 as a live performance tool can be augmented with a variety of third-party software. Live Event Sheet within CsoundQt can be used to modify the score in real-time. In addition, interfaces to other programming languages can be used to script Csound. A paper detailing the use of Csound with Qt or Pure Data in real-time musical synthesis was presented at the 2012 Linux Audio Conference The Ounk project attempts to integrate Python with Csound while CsoundAC provides a way to do algorithmic composition from Python using Csound as backend. Audivation's Csound for Live packages various opcodes into Max/MSP wrappers suitable for use in Ableton Live. Csound is also available for mobile systems (iOS, Android).


One Laptop per Child (OLPC)

Csound5 was chosen to be the audio/music development system for the OLPC project on the
XO-1 Laptop The OLPC XO (formerly known as $100 Laptop, Children's Machine, 2B1) is a low cost laptop computer intended to be distributed to children in developing countries around the world, to provide them with Access to Knowledge movement, access to know ...
platform.


See also

* Audio signal processing *
Software synthesizer A software synthesizer or softsynth is a computer program that generates digital audio, usually for music. Computer software that can create sounds or music is not new, but advances in processing speed now allow softsynths to accomplish the sam ...
* Computer music * Comparison of audio synthesis environments * List of music software


References


Further reading

* * * This is a book mostly about programming sound directly using the C language, but it does have a couple of chapters about programming Csound opcodes. *


External links

* {{Authority control Audio programming languages Free audio software Electronic music software Software synthesizers