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Blue requires Java 11 or greater JVM (Java Virtual Machine) to be installed on your system, as well as Csound. Java installations usually come in two flavors: a JRE (Java Runtime Environment) which contains just a JVM for running applications, and a JDK (Java Development Kit) which contains the JVM as well as development tools. Because Blue comes with scripting tools that use JDK features, it is recommended to install the full JDK, and not just the JRE.

To test to see if you have a JVM installed and what version, at a command prompt type "java -version". If you see something along the lines of "command not found" then you need to install a Java Virtual Machine.

If you do not have Java installed, the recommended JDK to install is AdoptOpenJDK, available at:

On this page, look for the download link for your platform. Be sure to choose the version of JDK that matches your CPU type and Csound version (choose 64-bit if in doubt).

Installing Blue

To install Blue, you should download the latest ZIP file from the Blue releases page here. For macOS users, download the macOS zip file which contains You can double-click the Application to run, as well as copy it to your Applications folder to install it.

For Linux and Windows users, download the appropriate zip file and unzip it. Inside of the bin folder you will see a "blue" script for Linux or a "blue64.exe" file for use on Windows. (A 32-bit version, "blue.exe", is also included for those using an older version of Csound that is compiled for 32-bit Windows.)

Note: After starting Blue, you may want to explore the example projects and pieces found in the Blue/example folder (or right-click and explore contents of if on OSX).

Platform Specific Notes

The section below has notes for individual platforms.


Blue uses the right mouse click often to show popup menus. If you do not have a right mouse button, you can use ctrl-click for all "rt-clicks" that are mentioned in this documentation.

To make use of the function key shortcuts (F1-F12), you will need to go into System Preferences, choose Keyboard, then enable "Use all F1, F2, etc. keys as standard function keys".

Installing Csound

Blue is able to interact with Csound either by calling Csound like a command-line program (classic Blue), or by directly interacting with Csound via the Csound API. Instructions on setting up Blue for each method is described below as well as discussion on benefits and limitations.

Using Blue with command-line Csound

This may be considered "classical" Blue usage and interaction with Csound as this was the method by which Blue ran with Csound for the first eight years in existance. The way Blue operates in this mode is by rendering the .Blue project into a temporary CSD file on disk, then calling Csound with that temporary CSD file in the same way as if you were on a command-line shell and executing Csound yourself with that file.

The benefit to this mode of Csound usage is that it is easier to switch out your version of Csound or use multiple versions of Csound on the same computer. It is also a little more stable than using the API in that if Csound crashes for some reason, it won't take down Blue with it. Also, it may be more performant to use the command-line mode. These benefits however need to be weighed against the benefits of using the API, which is described below.

To use the command-line version, one needs to set up the Csound executable option for Realtime and Disk Render settings in Program Options.

Using Blue with the Csound API

Enabling Blue to use the Csound API when rendering with Csound opens up the ability to manipulate and edit widget values and automations in realtime during a render, as well as the ability to use BlueLive on Windows. Because of its enhancement to the user-experience while rendering and composing, it is the preferred method of using Blue with Csound. Blue should work out-of-the-box with the API if Csound is installed using the installers provided on Github, or installed via a package manager if on Linux.


Blue currently only works with the API if the version of Csound used is compiled using 64-bit doubles. (The float version is not supported when using the API.) There are technical difficulties in supporting two different versions of Csound API in the same build and it is not known if or when the float build will be supported. For users interested in using the float build of Csound with Blue, you will need to run Blue using the command-line Csound mode.

Additionally, the architecture that Csound is compiled for must match the architecture of the Java runtime you are using. For example, on Windows, Csound is currently only built for x86_64/amd64 CPU (i.e. 64-bit Windows) and not x86 (i.e. 32-bit Windows). In this case, you will need to run Blue using a 64-bit Java Runtime. For OSX, this is not an issue as Csound is compiled as a universal binary for both i386 and x86_64. On Linux, it is likely that the version of Csound you install/compile and the Java Runtime that you install will likely be the same, but if the API does not show as available it may be something to check.

Blue uses the CsoundJNI Java binding for Csound. This requires that Blue can find your installed version of Csound but is configured to do so for standard Csound installations. If the API is not enabled when starting Blue, the following explains how to setup the API on different platforms.


Users using the Windows Installer for Csound should use the double precision version from Github. (This is the default.) After installing, the installer should setup everything such that Blue should work with the API. If for some reason it is unable to do so, you can modify the blue/etc/blue.conf file to tell Blue where to find the csound64.dll. For example, if the directory where csound64.dll is located is in c:\myCsound, open up blue/etc/blue.conf and modify the default so that it contains:

default_options="--branding blue -J-Xms256m -J-Xmx768m -J-Djava.library.path=c:/myCsound"


Linux users should install a doubles version of Csound. The version of Csound found in package repositories should be one compiled for doubles. After installing Csound, modify the blue/bin/blue file. Search for the lines that contain "-J-Djava.library.path=/usr/lib/jni" and modify /usr/lib/jni (the default for Debian/Ubuntu-based systems) to the directory where is located.


macOS users may use the installer for Csound from Github, install Csound with Homebrew, or self-compile. CsoundJNI is configured to find CsoundLib64 in all of the above scenarios for default installations.

Checking whether the API is enabled

To check if the API is enabled, open Blue and open up the Program Options. This is available from the Blue->Preferences menu option on OSX, and from the Tools->Options menu option Windows and Linux. In the Blue tab, under both Disk and Realtime Render settings, there is an option called "Render Method". If Csound 6 is availble on your system and Blue was able to find it, it will show a "Csound 6 API" option. If the Csound 6 Java API could be loaded, you will only have the "Commandline Runner" option which is always available.