Introduction to RTcmix

What is RTcmix?

RTcmix is a real-time software system for synthesizing and processing digital audio. It has two main parts: a front-end parsing system which reads ASCII scripts or “scores“ written using the Minc language, and a powerful back-end audio rendering engine which performs the event scheduling, audio I/O, sound synthesis and processing. It is written in C/C++ and is distributed open-source, free of charge. In certain respects, it is similar in function to other extant unit-generator-based software packages such as CSOUND, SuperCollider and (to a lesser extent) JSyn and Max/MSP – they do share a common heritage, after all. There are differences, however, between all these packages… and variety is of course the spice of life!

RTcmix compiles and runs on most Unix-like systems, including various flavors of Linux, macOS, IRIX, FreeBSD. A Windows port is available making use of the Max/MSP rtcmix~ object.

So if you’ve been searching the web high and low for just the right library of DSP functions to include in your latest\&greatest “killer” (or maybe “peacefully coexisting”?) app, then RTcmix may just be the Right Package for You.

How Can I Try it Out?

If you are working on a Mac or a Windows machine, the easiest way to experiment with RTcmix is to download, install, and run John Gibson’s RTcmixShell application. To make a start, paste the following three lines into the app’s score window and press “play”:

WAVETABLE(0, 4, 5000, 440)
WAVETABLE(1, 3, 5000, 440*3/2)
WAVETABLE(2, 2, 5000, 440*5/4)

There. You just made your first score, using the WAVETABLE instrument command. You can experiment with most of what is described in the reference pages using this application.

How Else Can I Use It?

RTcmix can be configured and compiled to run in several different modes:

Standalone
A command line version for most Unix-like systems, including various flavors of Linux, MacOS X, IRIX, and FreeBSD.
rtcmix~
All functionality compiled into an object for use in the Max/MSP and Pd graphical programming environments.
Embedded
All functionality, accessible via a public API, compiled into a dynamic library which can be linked into a larger application (which then handles audio I/O and rendering callbacks). RTcmixShell is an example of such an app.

Where Do I Download It?

If you are happy with the capabilities of RTcmixShell, you don’t need to download anything else! The app already contains the embedded library described above. For the others, depending on which configuration (mode) you decide to use, RTcmix is downloadable as either a precompiled binary or as configurable, compilable source code.

If you want to use RTcmix as a standalone Unix-style command, follow the step-by-step instructions for downloading, configuring and building the source on various platforms here.
If you want to use RTcmix as a Max/MSP object, follow the instructions for rtcmix~ here.
If you want to build an RTcmix dynamic library to embed in a larger software project, follow the step-by-step instructions for downloading, configuring and building the source on various platforms here but note that documentation for doing this on your own is a work-in-progress.

More About RTcmix

RTcmix currently includes the following components:

a library of low-level C/C++ functions and objects for performing most contemporary digital audio and signal-processing tasks
a substantial set of precompiled “instruments” instantiating a variety of DSP and sound-synthesis algorithms (click here for a list)
a fully-featured command-parsing language to allow easy incorporation of algorthmic control procedures in sound generation
an option to allow the Perl or Python programming languages to be used as the control/command-parsing environment for RTcmix
a robust and sample-accurate scheduler for timing and arbitrary event-scheduling
an ‘embedded’ RTcmix object and associated library to enable the entire RTcmix system (scheduler too!) to be compiled and used seamlessly within other C/C++ applications
a TCP/IP socket interface for external control of RTcmix from other processes or machines
the physical model and PhISEM routines from Perry Cook and Gary Scavone’s Synthesis ToolKit (STK) as well as affiliated RTcmix instruments using the stk routines
the ability to read/write most contemporary soundfile formats by via Bill Schottstaedt’s sndlib
a package of examples showing RTcmix use with MIDI, X11/Motif, wxWindows, Lisp, Open Sound Control (OSC), OpenGL, etc.
a set of command-line utility programs for playing and manipulating soundfiles
a Max/MSP rtcmix~ object, available for both macOS and Windows versions of max/msp
dynamic parameter modification
“pull” model for audio I/O (JACK, PortAudio, etc.)

RTcmix is derived from the original CMIX software, developed at Princeton University by Paul Lansky.

Contributors