chuck-max

A project to minimally embed the chuck engine in a Max/MSP external.

It currently has one external (chuck~) with the following features and limitations:

• Generate and process audio via an embedded chuck engine by running chuck files with global parameters controlled and adjusted in realtime by Max messages.

• Layer sounds from a single instance by running multiple chuck files concurrently.

• Add, remove, replace audio and audio processes on the fly using Chuck messages via Max messages.

• Includes most of the base ccrma chugins including WarpBuf and Fauck or Faust except for the following:

  • Fluidsynth
  • Ladspa

• Note that chuck-max has a sibling in the pd-chuck project.

This project is currently built on the chuck 1.5.2.5-dev (chai) engine.

Overview

• The chuck~ object can take the following arguments:

  • [chuck~] : single channel in/out, no default chuck file
  • [chuck~ <N>] : N channel in/out, no default chuck file
  • [chuck~ <filename>] : single channel in/out with default chuck file
  • [chuck~ <N> <filename>] : N channels with default chuck file

It is recommended to choose 2 channels for stereo configuration. If a <filename> argument is given it will be searched for according to the following search rules:

1. Assume it's an absolute path, use it if it exists.

2. Assume that it's a partial path with the package's examples folder as a prefix. So if stk/flute.ck is given as <filename>, the absolute path of the package examples folder is prepended to it and if the resulting path exists, it is used.

3. Assume <filename> exists in the parent patcher's directory. If so, use it. This is useful if you want to package patchers and chuck files together.

4. Use Max's locatefile_extended search function to search for the <filename> in the Max search path. The first successul result will be used.

Core Messages

As of the current version, chuck~ implements the core Chuck vm messages as Max messages:

Action	Max msg	Max msg (alias)
Add shred	add <file>	+ <filepath>
Remove shred	remove <shredID>	- <shredID>
Remove last shred	remove last	--
Remove all shreds	remove all
Replace shred	replace <shredID> <file>	= <shredID> <file>
VM status	status	^
Clear vm	clear vm	reset
Clear globals	clear globals
Reset id	reset id
Time	time

It's worth reading the ChucK Language Specification's section on Concurrency and Shreds to get a sense of what the above means. The first paragraph will be quoted here since it's quite informative:

ChucK is able to run many processes concurrently (the process behave as if they are running in parallel). A ChucKian process is called a shred. To spork a shred means creating and adding a new process to the virtual machine. Shreds may be sporked from a variety of places, and may themselves spork new shreds.

Utility Messages

The core set of chuck vm messesages is also extended in chuck-max with the following utility messages:

Action	Max msg
Set file attribute (does not run)	file <path>
Set full path to editor attribute	editor <path>
Prevent running shreds when dsp is off	run_needs_audio
Open file in external editor	edit <path>
Probe chugins	chugins
List of running shreds	info
Get/set loglevel (0-10)	loglevel & loglevel <n>
Get state of chuck vm	vm
Launch chuck docs in a browser	docs

Parameter Messages

Once a shred is running you can change its parameters by sending values from Max to the chuck~ object. To this end, ChucK makes available three mechanisms: global variables, global events, and callbacks which are triggered by events. chuck~ maps these chuck language elements to corresponding Max/MSP constructs as per the following table:

Action	ChucK	Max msg
Change param value (untyped)	global variable	<name> <value>
Dump global variables to console	global variable	globals
Trigger named event	global event	sig <name>
Trigger named event all shreds	global event	broadcast <name>

You change a global variable by sending a <variable-name> <value> message to a chuck~ instance where the value can be an int, float, string, array of ints or floats, etc. You can also trigger events by sending sig or signal messages, broadcast messages as per the above table.

Note: You can't use the ChucK types of dur or time in Max. Also, while in the above case, the Max msg seems untyped, it must match the type of the chuck global variable. So if you connect a Max number or flownum object to a message box, it needs to match the type of the global variable (int/float).

See help/chuck~.maxhelp and patchers in the patchers/tests directory for a demonstration of current features.

Parameter Messages using Callbacks (Advanced Usage)

In addition to the typical way of changing parameters there is also an extensive callback system which includes listening / stop-listening for events associated with callbacks, triggering them via sig and broadcast messages and also setting typed global variables via messages and symmetrically getting their values via typed callbacks:

Action	ChucK	Max msg
Listen to event (one shot)	global event	listen <name> or listen <name> 0
Listen to event (forever)	global event	listen <name> 1
Stop listening to event	global event	unlisten <name>
Trigger named callback	global event	sig <name>
Trigger named callback all shreds	global event	broadcast <name>
Get int variable	global variable	get int <name>
Get float variable	global variable	get float <name>
Get string variable	global variable	get string <name>
Get int array	global variable	get int[] <name>
Get float array	global variable	get float[] <name>
Get int array indexed value	global variable	get int[i] <name> <index>
Get float array indexed value	global variable	get float[i] <name> <index>
Get int associative array value	global variable	get int[k] <name> <key>
Get float associative array value	global variable	get float[k] <name> <key>
Set int variable	global variable	set int <name> <value>
Set float variable	global variable	set float <name> <value>
Set string variable	global variable	set string <name> <value>
Set int array	global variable	set int[] <name> v1, v2, ..
Set float array	global variable	set float[] <name> v1, v2, ..
Set int array indexed value	global variable	set int[i] <name> <index> <value>
Set float array indexed value	global variable	set float[i] <name> <index> <value>
Set int associative array value	global variable	set int[k] <name> <key> <value>
Set float associative array value	global variable	set float[k] <name> <key> <value>

Developer Note

In order to customize the current set of callbacks (which currently just post the value of the parameters to the Max console), an advanced user will want to modify them to do something other than the default and then re-compile the external.

In practice, callbacks in chuck-max are constrained by what their function signatures allow. To do something useful one will typically want to access the pointer to an instance of the chuck~ object which is not directly available as an argument to any the callbacks. For example, in the case of the cb_get_int callback, one only has the parameter name and value:

void cb_get_int(const char* name, long val)
{
    post("cb_get_int: name: %s value: %d", name, val);
}

To get around this limitation, one can use the knowledge that chuck~ instances are given the scripting name chuck-<x> where x is the order of instanciation and that one can get the retrieve the relevant object pointer by using void *object_findregistered(t_symbol *name_space, t_symbol *s) as in:

void cb_get_int(const char* name, t_CKINT val)
{
    t_object* x;

    for (auto name : CK_INSTANCE_NAMES) {
        x = (t_object*)object_findregistered(CLASS_BOX, gensym(name.c_str()));
        object_post(x, (char*)"name: %s value: %d", name.c_str(), val);
    }
}

It's not elegant, but it works until something better comes along.

Requirements

Note that this external is currently only developed and tested on macOS, although a Windows version is on the TODO list.

It requires the following to be available on your system:

1. Xcode from the App store or Xcode Command Line Tools via xcode-select –install

2. cmake

3. bison

4. flex

The last three can be installed using Homebrew as follows:

brew install cmake bison flex

Compilation

Currently chuck~ can only be built on macOS. Of course, any help to progrss a windows version variant would be welcome!

The buildsystem consists of a minimal Makefile frontend with CMake driving the build on the backend.

To get up and running:

git clone https://github.com/shakfu/chuck-max.git
cd chuck-max
make setup

Note: make setup does two things: (1) retrieve max-sdk-base via a git submodule and makes the package and its contents available to be used by Max by creating a symlink of the chuck-max folder in $HOME/Documents/Max 8/Packages.

From this point you have three options:

1. make: Base system: (external + base ccrma chugins excluding Fauck or Faust and WarpBuf)*

2. make full: Base system + Faust and Warpbuf chugins with full libsndfile format support

3. make light: Base system + Faust and Warpbuf chugins with libsndfile support only .wav files.

[*] The Fauck or Faust chugin will be referred to by either of these names.

Also note that by default make builds the external according to the native architecture of the mac it is compiled on. You can build the base system with universal support by typing make universal instead.

If there's a need to update and re-build the external just type the following in the root of the project.

git pull
make

Install the Warpbuf Chugin (Optional)

With WarpBuf you can time-stretch and independently transpose the pitch of an audio file.

This chugin can be built by make full instead of make in the build process above or if you are just using cmake then set option -DENABLE_WARPBUF=ON

Install the Fauck Chugin (Optional)

The fauck chugin contains the full llvm-based faust engine and dsp platform which makes it very powerful and also quite large compared to other chugins (at around 45 MB stripped down). It requires at least 2 output channels to work properly.

This chugin can be built by make full and make light options instead of make in the build process above or if you are just using cmake then set option -DENABLE_FAUCK=ON

A future aim is to include a stripped down version of this fauck chugin which only supports .wav files and and only contains the faust standard library in an official chuck-max package.

CAVEAT: the Faust chugin has unresolved cleanup bug which may cause Max to crash after all patch windows are closed and Max is exited.

Usage

Open the help file help/chuck~.maxhelp for a demo. Check out the patchers folders for further examples of use.

Known Unresolved Bugs

1. If a chuck file contains a custom event and the Max patch sends a clear vm or reset before running the chuck file while Max audio is turned off, it may cause Max to crash. See github issue #11 for updates on this. The interim solution is to only run chuck files with Max audio on, and there's an attribute run_needs_audio to force this and prevent the crash. Thanks to @HighHarmonics2 for discovering this one.

2. Use of the Fauck or Faust chugin will cause Max to crash when the user quits Max after all patch windows are closed.

Credits

This project thanks the following:

• Professors GE Wang and Perry Cook and all chuck and chuggin contributors for creating the amazing ChucK language and chuggin ecosystem!

• Professor Perry Cook for co-authoring Chuck and creating the Synthesis Toolkit which is integrated with chuck.

• Professor Brad Garton for creating the original chuck~ external for Max 5. My failure to build it and run it on Max 8 motivated me to start this project.

• David Braun, the author of the very cool and excellent DawDreamer project, for creating the excellent ChucKDesigner project which embeds chuck in a Touch Designer plugin. His project provided a super-clear blueprint on how to embed libchuck in another host or plugin system and was essential to this project.