connoise  2.1.0


Connoise ("Connected Noise Machine") is a software modular audio synthesizer.

Get the code:

Read the docs:

Usage overview


The configuration of the synthesizer is read from .cno files to form a System.

At the moment, the synthesis is run in real time, but for a limited and defined duration.

$ ./connoise -h
connoise version 0.1.0 2021-02-06 19:21
SPDX-License-Identifier: GPL-3.0-only
Copyright © 2020 Doug Hammond
Usage: connoise [options] filename
Positional arguments:
filename connoise file to run
Optional arguments:
-h --help show this help message and exit
-r --sample-rate synthesis sample rate
-b --buffer-size audio buffer size
-d --duration synthesis run duration
-t --tail synthesis tail duration
-g --dot-graph output dot graph of the system


$ ./connoise -r 44100 -d 5 -t 1 ./tests/data/inputs/07-pings.cno


$ ./connoise-gui

There's no written user manual for the GUI, but most conventional UI operations work as expected.


$ ./connoise-test

.cno File Format

connoise implements its own text based file format for describing a synthesizer System.

The file parser is reasonably forgiving with regards to formatting known entities, you can use whitespace (including newlines) liberally (or not, if you prefer).

However, the parser will currently halt when met with unknown input. Keywords and blocks must use the exact syntax specified here. Comments are not yet supported.

Blocks are parsed in order as they are seen, therefore Modules must be instantiated before you can connect them, and before you can set the System output.

Statements which reference unknown IDs or Parameter names will be safely ignored, although your System may then be incompletely configured.

Illustrated here is the canonical formatting for known blocks.


Text (string) values are mostly written literally, unquoted.


id my-module-id

Text values for Module params, are to be Quoted with double quote character ". These `QuotedString` values may not contain any newline or " quote characters, unless 'escaped' with \, as per normal C string rules.


path "/this/is/my/quoted/string/path"
metadata "This is some \"quoted\" text.\nAnd the next line."

Some strings permit different character sets, these are described for each string below.


Numbers can be written as either whole numbers (e.g. 42) or with also a decimal point and further digits (e.g. 3.14152). You can also use negative prefix (e.g. -0.25). No other formats are accepted.

Note that number ranges and/or suitability for use in a given parameter is not validated. You can for example happily specify a negative frequency and marvel that it works whilst you ponder what that really means.

Module & Output Blocks

Describes the instantiation of a Module or System Output.

Module <TYPE> {
id <ID>
params {
Output <TYPE> {
id <ID>
params {

params describes the inital value of Module parameters, particularly useful if your Module does not receive those values via a connection to another Module. Unconnected params will retain their initial value for the duration of rendering.

You need not specify values for all possible Module params, although it is a good idea to, since otherwise the Module will use its probably useless defaults.

If you do not wish to specify any initial params, you can omit the entire block from Module.

Every Module has and supports a QuotedString param called label, which is used by the GUI to help you identify things.

  • <TYPE>, String [a-zA-Z0-9_]: The type of Module to instantiate
  • <ID>, Number : Unique identifier of the Module in the System
  • <PARAM NAME>, String [a-zA-Z0-9]: Module parameter name
  • <PARAM VALUE>, Number or QuotedString: Module parameter initial value


Creates a connection from one Module output port to one Module or Output input port.

You can connect a Module directly, or indirectly to itself. Don't blame me if you create an explosive feedback loop. Probably a good idea to (future: render to WAV, or) turn your headphones/speakers right down when testing new System configurations. Perhaps best to keep your System acyclic.

Connection {
  • <ID>, Number: Unique identifier of a Module in the System
  • <OUTPUT NAME>, String [a-zA-Z0-9]: Name of the first Module's output
  • <INPUT NAME>, String [a-zA-Z0-9]: Name of the second Module's input


Describes properties of the system as a whole.

System {
metadata {

metadata describes additional information for the System; e.g. GUI layout data. This is entirely optional.

  • <KEY>, String [a-zA-Z0-9-]: The name of the metadata item
  • <VALUE>, QuotedString: Value of the metadata item


This is a standard cmake project. So far, it has only been compiled on Ubuntu Linux 20. Other OSs or distros may or may not work.

$ mkdir build
$ cd build
build$ cmake ..
build$ make -j


For build:

  • cmake
  • gcc or llvm
  • doxygen for API documentation

For runtime:

  • argparse
  • boost::graph
  • libsndfile
  • pegtl
  • SDL2
  • tbb

For GUI:

  • some kind of OpenGL back-end, e.g. gl3w
  • imgui
  • imgui bindings for: opengl3-glbinding, opengl3-glew, opengl3-gl3w, sdl2
  • tinyfiledialogs
  • imgui-node-editor

For test:

  • catch2

I can recommend using vcpkg for dependency package management.


This software is licensed under GPL 3.0; See LICENSE file.

// SPDX-License-Identifier: GPL-3.0-only
// Copyright © 2020 Doug Hammond