numchuck 0.1.5

Python bindings for ChucK audio programming language

numchuck

Python bindings for the ChucK audio programming language using nanobind.

The numchuck library provides interactive control over ChucK, enabling live coding workflows, bidirectional Python/ChucK communication, and comprehensive VM introspection—all while maintaining the existing real-time and offline audio capabilities.

Overview

numchuck is a high-performance Python wrapper for ChucK that provides:

Library

• Python Programmatic Access to ChucK API — Load, compile, and concurrently execute .ck files and ChucK code into audio processing or generated shreds. Manage the VM using python code: configure parameters, monitor timing, and control shred lifecycles.

• Flexible Execution — Choose between real-time audio playback and recording using asynchronous RtAudio or offline input from and rendering to numpy arrays.

• Advanced Audio Processing — Harness ChucK's complete synthesis, filtering, and DSP capabilities.

• Live Coding — Hot-swap code, replace active shreds, and inspect VM state in real time.

• Plugin Support — Extend functionality with ChucK chugins for additional instruments and effects.

• Dynamic Interaction - Bidirectional communication between ChucK and Python through global variables, event triggers, and callbacks.

User Interface

• Multi-Tab Editor — Full-screen ChucK editor with syntax highlighting; use F5 to spork and F6 to replace.

• Interactive REPL — Terminal-style interface supporting ChucK commands and code completion.

• Automatic Versioning — Keeps track of live coding sessions (file.ck → file-1.ck → file-1-1.ck).

• Command-Line Mode — Run ChucK files directly from the terminal, with support for duration and silent modes.

Installation

Install from pypi

pip install numchuck

or

uv add numchuck

Build from source

# Clone the repository
git clone <repository-url>
cd numchuck

# Build the extension
make build

# Run tests
make test

Quick Start

Command-Line Interface

numchuck provides three modes of operation:

1. Multi-Tab Editor (for livecoding)

# Launch the editor
python -m numchuck edit

# Open specific files in tabs
python -m numchuck edit bass.ck melody.ck

# Enable project versioning
python -m numchuck edit --project mymusic

# Start with audio enabled
python -m numchuck edit --start-audio --project mymusic

Editor Features:

• Multi-tab editing with ChucK syntax highlighting
• F5 or Ctrl-R to spork (compile and run current buffer)
• F6 to replace running shred with current buffer
• Ctrl-O to open files with interactive dialog (Tab for path completion)
• Ctrl-S to save files
• Ctrl-T for new tab, Ctrl-W to close tab
• Ctrl-N/Ctrl-P (or Ctrl-PageDown/PageUp) to navigate tabs
• Tab names show shred IDs after sporking (e.g., bass-1.ck)
• Project versioning: file.ck → file-1.ck → file-1-1.ck
• F1/F2/F3 for help/shreds/log windows
• Ctrl-Q to exit

2. Interactive REPL

# Launch the REPL
python -m numchuck repl

# Load files on startup
python -m numchuck repl bass.ck melody.ck

# Enable project versioning
python -m numchuck repl --project mymusic

# Start with audio enabled
python -m numchuck repl --start-audio

# Disable smart Enter mode
python -m numchuck repl --no-smart-enter

# Hide sidebar (can toggle with F2)
python -m numchuck repl --no-sidebar

REPL Commands:

• add <file> or + <file> - Spork a file
• remove <id> or - <id> - Remove a shred
• remove all or - all - Remove all shreds
• replace <id> <file> - Replace shred with file
• status - Show VM status
• time - Show ChucK time
• Type help or press F1 for full command reference

3. Command-Line Execution

# Execute ChucK files from command line
python -m numchuck run myfile.ck

# Run multiple files
python -m numchuck run bass.ck melody.ck

# Run for 10 seconds then exit
python -m numchuck run myfile.ck --duration 10

# Silent mode (no audio)
python -m numchuck run myfile.ck --silent

# Custom sample rate
python -m numchuck run myfile.ck --srate 48000

4. Version and Info

# Show version
python -m numchuck version

# Show ChucK and numchuck info
python -m numchuck info

Interface Features:

• Full-screen layout: Professional terminal UI with multiple display areas
• Live topbar: Minimal display showing shred IDs [1] [2] [3]
• Shreds table: Detailed shred information table (F2) with ID, name (folder/file), and elapsed time since spork
• Error display bar: Red error bar shows command errors without disrupting layout
• Help window: Built-in command reference (toggle with F1)
• Log window: Scrollable ChucK VM output capture (toggle with Ctrl+L)
• Mouse support: Scroll through log output with mouse wheel
• Scrollable input: Main input area with scrollbar for long code

Editing Features:

• Smart Enter mode: Enter submits commands immediately, but allows multiline ChucK code editing
• ChucK syntax highlighting: Full Pygments lexer for ChucK language with color themes
• ChucK code completion: Tab completion for keywords, types, UGens, and standard library
• Intelligent code detection: Automatically compiles multiline ChucK code
• Tab completion: Commands, .ck files, and ChucK language elements
• Command history: Persistent history with Ctrl+R search
• Colored prompt: [=>] matches ChucK logo styling

Common Keyboard Shortcuts (Editor & REPL):

• F1 - Toggle help window
• F2 - Toggle shreds table (detailed view with ID, folder/filename, elapsed time)
• F3 - Toggle log window (ChucK VM output)
• Ctrl+Q - Exit application
• Tab - Command and ChucK code completion
• Up/Down - Navigate command history

Project Versioning

When using --project <name>, numchuck automatically versions your files as you livecode:

~/.numchuck/projects/mymusic/
  bass.ck           # Original file
  bass-1.ck         # After first spork (shred ID 1)
  bass-1-1.ck       # After first replace of shred 1
  bass-1-2.ck       # After second replace of shred 1
  melody-2.ck       # Second file sporked (shred ID 2)
  melody-2-1.ck     # After replace of shred 2

This creates a complete history of your livecoding session, making it easy to:

• Review your creative process
• Recover previous versions
• Replay session timeline
• Share reproducible livecoding performances

High-Level API (Recommended)

The Chuck class provides a Pythonic interface with properties and simplified methods:

from numchuck import Chuck

# Create with parameters (auto-initializes)
chuck = Chuck(sample_rate=48000, output_channels=2)

# Properties instead of get_param/set_param
print(chuck.sample_rate)   # 48000
print(chuck.version)       # "1.5.5.3-dev (chai)"

# Compile and run
success, shreds = chuck.compile("SinOsc s => dac; 1::second => now;")
output = chuck.run(44100)  # Returns numpy array

# Shred management
print(chuck.shreds)        # [1]
chuck.remove_shred(1)
chuck.clear()

# Synchronous global variables
chuck.compile("global int tempo;")
chuck.run(100)
chuck.set_int("tempo", 120)
val = chuck.get_int("tempo")  # 120

# Events
chuck.signal_event("trigger")
chuck.on_event("response", my_callback)

# Access low-level API when needed
chuck.raw.set_param(...)

Low-Level API

For fine-grained control, use the low-level API via numchuck._numchuck:

from numchuck._numchuck import ChucK, start_audio, stop_audio

Real-Time Audio

from numchuck._numchuck import (
    ChucK, start_audio, stop_audio, shutdown_audio,
    PARAM_SAMPLE_RATE, PARAM_OUTPUT_CHANNELS
)
import time

# Create and configure ChucK
chuck = ChucK()
chuck.set_param(PARAM_SAMPLE_RATE, 44100)
chuck.set_param(PARAM_OUTPUT_CHANNELS, 2)
chuck.init()

# Compile ChucK code
chuck.compile_code('''
    SinOsc s => dac;
    440 => s.freq;
    while(true) { 1::samp => now; }
''')

# Start real-time audio playback
start_audio(chuck)
time.sleep(2)  # Play for 2 seconds
stop_audio()
shutdown_audio()

Offline Rendering

from numchuck._numchuck import ChucK, PARAM_SAMPLE_RATE, PARAM_OUTPUT_CHANNELS
import numpy as np

# Create ChucK instance
chuck = ChucK()
chuck.set_param(PARAM_SAMPLE_RATE, 44100)
chuck.set_param(PARAM_OUTPUT_CHANNELS, 2)
chuck.init()

# Compile code
chuck.compile_code('''
    SinOsc s => dac;
    440 => s.freq;
    while(true) { 1::samp => now; }
''')

# Render to numpy array
frames = 512
output = np.zeros(frames * 2, dtype=np.float32)
chuck.run(np.zeros(0, dtype=np.float32), output, frames)

API Reference

High-Level API (numchuck.Chuck)

The Chuck class provides a Pythonic wrapper with properties and simplified methods.

from numchuck import Chuck

Constructor

Chuck(
    sample_rate: int = 44100,
    input_channels: int = 2,
    output_channels: int = 2,
    working_directory: str = "",
    chugin_enable: bool = True,
    user_chugins: list[str] | None = None,
    vm_adaptive: bool = False,
    vm_halt: bool = False,
    auto_depend: bool = False,
    deprecate_level: int = 1,
    dump_instructions: bool = False,
    otf_enable: bool = False,
    otf_port: int = 8888,
    tty_color: bool = False,
    tty_width_hint: int = 80,
    auto_init: bool = True,
)

Properties

Property	Type	Description
sample_rate	int	Audio sample rate in Hz
input_channels	int	Number of input channels
output_channels	int	Number of output channels
working_directory	str	Working directory for file operations
version	str	ChucK version string (read-only)
chugin_enable	bool	Whether chugin loading is enabled
user_chugins	list[str]	List of user chugin paths
vm_adaptive	bool	Whether adaptive VM timing is enabled
vm_halt	bool	Whether VM halts when no shreds remain
auto_depend	bool	Whether automatic dependency resolution is enabled
deprecate_level	int	Deprecation warning level (0=none, 1=warn, 2=error)
dump_instructions	bool	Whether VM instruction dumping is enabled
otf_enable	bool	Whether on-the-fly programming is enabled
otf_port	int	Port for on-the-fly programming
tty_color	bool	Whether colored terminal output is enabled
tty_width_hint	int	Terminal width hint for formatting
compiler_highlight_on_error	bool	Syntax highlighting in error messages
is_realtime_audio_hint	bool	Hint for real-time audio mode
otf_print_warnings	bool	Whether OTF compiler warnings are printed
shreds	list[int]	List of all active shred IDs
raw	ChucK	Access to underlying low-level ChucK instance

Core Methods

• init() -> bool - Initialize ChucK (called automatically if auto_init=True)
• compile(code, args="", count=1, immediate=False) -> tuple[bool, list[int]] - Compile ChucK code
• compile_file(path, args="", count=1, immediate=False) -> tuple[bool, list[int]] - Compile from file
• run(num_frames, *, output=None, input=None, reuse=False) -> np.ndarray - Run VM and return output audio
  • No args: allocates new buffer each call
  • output=buf: uses provided buffer (zero allocation)
  • input=buf: uses provided input buffer
  • reuse=True: uses internal buffer (zero GC without manual management)
• advance(num_frames) -> None - Advance VM time without returning audio (for callbacks/events)

Shred Management

• remove_shred(shred_id) -> None - Remove a shred by ID
• replace_shred(shred_id, code, args="") -> int - Replace running shred with new code, returns new shred ID
• shred_info(shred_id) -> dict | None - Get shred information
• clear() - Remove all shreds from VM
• reset_id() - Reset shred ID counter

Global Variables

• set_int(name, value) - Set global int
• get_int(name, run_frames=256) -> int - Get global int (synchronous)
• set_float(name, value) - Set global float
• get_float(name, run_frames=256) -> float - Get global float (synchronous)
• set_string(name, value) - Set global string
• get_string(name, run_frames=256) -> str - Get global string (synchronous)
• get_int_async(name, callback) - Get global int via callback
• get_float_async(name, callback) - Get global float via callback
• get_string_async(name, callback) - Get global string via callback

Events

• signal_event(name) -> None - Signal event (wakes one shred)
• broadcast_event(name) -> None - Broadcast event (wakes all shreds)
• on_event(name, callback, listen_forever=True) -> int - Register event callback, returns callback ID
• stop_listening_for_event(name, callback_id) -> None - Stop listening for event

Console Output

• set_stdout_callback(callback) - Capture ChucK stdout (chout)
• set_stderr_callback(callback) - Capture ChucK stderr (cherr)

---

Low-Level API (numchuck._numchuck.ChucK)

The low-level API provides direct access to all ChucK functionality with explicit parameter management.

from numchuck._numchuck import ChucK

Initialization Methods

• __init__() - Create a new ChucK instance
• init() -> bool - Initialize ChucK with current parameters
• start() -> bool - Explicitly start ChucK VM (called implicitly by run() if needed)

Parameter Configuration

• set_param(name: str, value: int) -> int - Set integer parameter
• set_param_float(name: str, value: float) -> int - Set float parameter
• set_param_string(name: str, value: str) -> int - Set string parameter
• set_param_string_list(name: str, value: list[str]) -> int - Set string list parameter
• get_param_int(name: str) -> int - Get integer parameter
• get_param_float(name: str) -> float - Get float parameter
• get_param_string(name: str) -> str - Get string parameter
• get_param_string_list(name: str) -> list[str] - Get string list parameter

Compilation Methods

• compile_code(code: str, args: str = "", count: int = 1, immediate: bool = False, filepath: str = "") -> tuple[bool, list[int]]

  • Compile ChucK code from string
  • Returns: (success, shred_ids)
  • Parameters:
    • code: ChucK code to compile
    • args: Additional arguments (separated by ':')
    • count: Number of shred instances to spork
    • immediate: If True, schedule immediately; if False, queue for next time step
    • filepath: Optional filepath for path-related operations

• compile_file(path: str, args: str = "", count: int = 1, immediate: bool = False) -> tuple[bool, list[int]]

  • Compile ChucK code from file
  • Returns: (success, shred_ids)

Audio Processing

• run(input: np.ndarray, output: np.ndarray, num_frames: int)
  • Process audio for specified number of frames (synchronous/offline)
  • input: Input buffer (1D numpy array, dtype=np.float32)
    • Size must be num_frames * input_channels
  • output: Output buffer (1D numpy array, dtype=np.float32, C-contiguous)
    • Size must be num_frames * output_channels
  • num_frames: Number of audio frames to process

Real-Time Audio (RtAudio)

• start_audio(chuck: ChucK, sample_rate: int = 44100, num_dac_channels: int = 2, num_adc_channels: int = 0, dac_device: int = 0, adc_device: int = 0, buffer_size: int = 512, num_buffers: int = 8) -> bool

  • Start real-time audio playback using RtAudio
  • Audio plays asynchronously in the background
  • Returns: True if successful

• stop_audio() -> bool

  • Stop real-time audio playback
  • Returns: True if successful

• shutdown_audio(msWait: int = 0)

  • Shutdown audio system completely
  • msWait: Milliseconds to wait before shutdown

• audio_info() -> dict

  • Get current audio system information
  • Returns dict with keys: sample_rate, num_channels_out, num_channels_in, buffer_size

Global Variable Management

• set_global_int(name: str, value: int) - Set a global int variable
• set_global_float(name: str, value: float) - Set a global float variable
• set_global_string(name: str, value: str) - Set a global string variable
• get_global_int(name: str, callback: Callable[[int], None]) - Get a global int (async via callback)
• get_global_float(name: str, callback: Callable[[float], None]) - Get a global float (async via callback)
• get_global_string(name: str, callback: Callable[[str], None]) - Get a global string (async via callback)
• set_global_int_array(name: str, values: list[int]) - Set a global int array
• set_global_float_array(name: str, values: list[float]) - Set a global float array
• set_global_int_array_value(name: str, index: int, value: int) - Set array element by index
• set_global_float_array_value(name: str, index: int, value: float) - Set array element by index
• set_global_associative_int_array_value(name: str, key: str, value: int) - Set map value by key
• set_global_associative_float_array_value(name: str, key: str, value: float) - Set map value by key
• get_global_int_array(name: str, callback: Callable[[list[int]], None]) - Get int array (async)
• get_global_float_array(name: str, callback: Callable[[list[float]], None]) - Get float array (async)
• get_all_globals() -> list[tuple[str, str]] - Get list of all globals as (type, name) pairs

Global Event Management

• signal_global_event(name: str) - Signal a global event (wakes one waiting shred)
• broadcast_global_event(name: str) - Broadcast a global event (wakes all waiting shreds)
• listen_for_global_event(name: str, callback: Callable[[], None], listen_forever: bool = True) -> int - Listen for event, returns listener ID
• stop_listening_for_global_event(name: str, callback_id: int) - Stop listening using listener ID

Shred Management

• remove_shred(shred_id: int) - Remove a shred by ID
• remove_all_shreds() - Remove all running shreds from VM
• get_all_shred_ids() -> list[int] - Get IDs of all running shreds
• get_ready_shred_ids() -> list[int] - Get IDs of ready (not blocked) shreds
• get_blocked_shred_ids() -> list[int] - Get IDs of blocked shreds
• get_last_shred_id() -> int - Get ID of last sporked shred
• get_next_shred_id() -> int - Get what the next shred ID will be
• get_shred_info(shred_id: int) -> dict - Get shred info (id, name, is_running, is_done)

VM Control

• clear_vm() - Clear the VM (remove all shreds)
• clear_globals() - Clear global variables without clearing the VM
• reset_shred_id() - Reset the shred ID counter
• replace_shred(shred_id: int, code: str, args: str = "") -> int - Replace running shred with new code

Status and Utility

• is_init() -> bool - Check if ChucK is initialized
• vm_running() -> bool - Check if VM is running
• now() -> float - Get current ChucK time in samples

Console Output Control

• set_chout_callback(callback: Callable[[str], None]) -> bool - Capture ChucK console output
• set_cherr_callback(callback: Callable[[str], None]) -> bool - Capture ChucK error output
• toggle_global_color_textoutput(onOff: bool) - Enable/disable color output
• probe_chugins() - Print info on all loaded chugins

Static Methods

• version() -> str - Get ChucK version string
• int_size() -> int - Get ChucK integer size in bits
• num_vms() -> int - Get number of active ChucK VMs
• set_log_level(level: int) - Set global log level
• get_log_level() -> int - Get global log level
• poop() - ChucK poop compatibility
• set_stdout_callback(callback: Callable[[str], None]) -> bool - Set global stdout callback (static)
• set_stderr_callback(callback: Callable[[str], None]) -> bool - Set global stderr callback (static)
• global_cleanup() - Global cleanup for all ChucK instances

Parameter Constants

Core Parameters

• PARAM_VERSION - ChucK version
• PARAM_SAMPLE_RATE - Sample rate (default: 44100)
• PARAM_INPUT_CHANNELS - Number of input channels
• PARAM_OUTPUT_CHANNELS - Number of output channels

VM Configuration

• PARAM_VM_ADAPTIVE - Adaptive VM mode
• PARAM_VM_HALT - VM halt on errors
• PARAM_OTF_ENABLE - On-the-fly programming enable
• PARAM_OTF_PORT - On-the-fly programming port
• PARAM_DUMP_INSTRUCTIONS - Dump VM instructions
• PARAM_AUTO_DEPEND - Auto dependency resolution
• PARAM_DEPRECATE_LEVEL - Deprecation warning level

Paths

• PARAM_WORKING_DIRECTORY - Working directory path
• PARAM_CHUGIN_ENABLE - Enable chugins (plugins)
• PARAM_USER_CHUGINS - User chugin paths
• PARAM_IMPORT_PATH_SYSTEM - System import search paths
• PARAM_IMPORT_PATH_PACKAGES - Package import search paths
• PARAM_IMPORT_PATH_USER - User import search paths

Display & Debugging

• PARAM_OTF_PRINT_WARNINGS - Print on-the-fly compiler warnings
• PARAM_IS_REALTIME_AUDIO_HINT - Hint for real-time audio mode
• PARAM_COMPILER_HIGHLIGHT_ON_ERROR - Syntax highlighting in error messages
• PARAM_TTY_COLOR - Enable color output in terminal
• PARAM_TTY_WIDTH_HINT - Terminal width hint for formatting

Module Functions

• version() -> str - Get ChucK version (convenience function)

Important Notes

Audio Buffer Types

ChucK uses float (32-bit) for audio samples by default. Always use np.float32 for numpy arrays:

# Correct
output_buffer = np.zeros(num_frames * channels, dtype=np.float32)

# Incorrect - will produce silent output
output_buffer = np.zeros(num_frames * channels, dtype=np.float64)

Buffer Layout

Audio buffers are interleaved:

• For stereo output: [L0, R0, L1, R1, L2, R2, ...]
• Buffer size = num_frames * num_channels

Time Advancement

ChucK code must advance time to generate audio:

# Good - infinite loop advances time
code = '''
SinOsc s => dac;
440 => s.freq;
while(true) { 1::samp => now; }
'''

# Bad - shred exits immediately, no audio
code = '''
SinOsc s => dac;
440 => s.freq;
'''

Examples

Real-Time Audio Playback

import numchuck
import time

# Create and initialize ChucK
chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()

# Compile ChucK code
chuck.compile_code('''
    SinOsc s => dac;
    440 => s.freq;
    0.5 => s.gain;
    while(true) { 1::samp => now; }
''')

# Start real-time audio (plays asynchronously)
numchuck.start_audio(chuck, sample_rate=44100, num_dac_channels=2)

# Audio plays in background
time.sleep(3)  # Play for 3 seconds

# Stop audio
numchuck.stop_audio()
numchuck.shutdown_audio()

Offline Audio Processing

import numchuck
import numpy as np

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()

chuck.compile_code('''
    SinOsc s => dac;
    440 => s.freq;
    0.5 => s.gain;
    while(true) { 1::samp => now; }
''')

# Process audio synchronously
frames = 512
output = np.zeros(frames * 2, dtype=np.float32)
chuck.run(np.zeros(0, dtype=np.float32), output, frames)

# output now contains audio samples

Parameter Control

# Get ChucK version
print(f"ChucK version: {numchuck.version()}")

# Configure VM
chuck.set_param(numchuck.PARAM_VM_HALT, 0)
chuck.set_param_string(numchuck.PARAM_WORKING_DIRECTORY, "/path/to/files")

# Check status
print(f"Initialized: {chuck.is_init()}")
print(f"Current time: {chuck.now()} samples")

Multiple Shreds

# Compile the same code 3 times
success, ids = chuck.compile_code(code, count=3)
print(f"Spawned shreds: {ids}")  # [1, 2, 3]

# Remove all shreds
chuck.remove_all_shreds()

Loading ChucK Files

import numchuck

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()

# Compile from file
success, shred_ids = chuck.compile_file("examples/basic/blit2.ck")

# Start playback
numchuck.start_audio(chuck)
import time; time.sleep(2)
numchuck.stop_audio()
numchuck.shutdown_audio()

Using Chugins (Plugins)

import numchuck

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)

# Enable chugins and set search path
chuck.set_param(numchuck.PARAM_CHUGIN_ENABLE, 1)
chuck.set_param_string(numchuck.PARAM_USER_CHUGINS, "./examples/chugins")

chuck.init()

# Use a chugin in code
code = '''
SinOsc s => Bitcrusher bc => dac;
440 => s.freq;
8 => bc.bits;
while(true) { 1::samp => now; }
'''
chuck.compile_code(code)

Global Variables (Python/ChucK Communication)

import numchuck
import numpy as np

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_INPUT_CHANNELS, 2)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()
chuck.start()

# Define global variables in ChucK
chuck.compile_code('''
    global int tempo;
    global float frequency;
    global string mode;

    SinOsc s => dac;

    while(true) {
        frequency => s.freq;
        1::samp => now;
    }
''')

# Helper to run audio cycles (VM processes messages during audio)
def run_cycles(count=5):
    buf_in = np.zeros(512 * 2, dtype=np.float32)
    buf_out = np.zeros(512 * 2, dtype=np.float32)
    for _ in range(count):
        chuck.run(buf_in, buf_out, 512)

# Set globals from Python
chuck.set_global_int("tempo", 120)
chuck.set_global_float("frequency", 440.0)
chuck.set_global_string("mode", "major")
run_cycles()

# Get globals via callback
result = []
chuck.get_global_float("frequency", lambda val: result.append(val))
run_cycles()
print(f"Current frequency: {result[0]} Hz")

# List all globals
globals_list = chuck.get_all_globals()
print(f"Globals: {globals_list}")

Global Events (Event-Driven Communication)

import numchuck
import numpy as np

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_INPUT_CHANNELS, 2)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()
chuck.start()

# ChucK code with global events
chuck.compile_code('''
    global Event trigger;
    global Event response;
    global int noteValue;

    SinOsc s => dac;

    fun void player() {
        while(true) {
            trigger => now;
            Std.mtof(noteValue) => s.freq;
            100::ms => now;
            response.broadcast();
        }
    }

    spork ~ player();
''')

def run_cycles(count=5):
    buf_in = np.zeros(512 * 2, dtype=np.float32)
    buf_out = np.zeros(512 * 2, dtype=np.float32)
    for _ in range(count):
        chuck.run(buf_in, buf_out, 512)

# Listen for response from ChucK
response_count = []
def on_response():
    response_count.append(1)
    print(f"Response received! Total: {len(response_count)}")

listener_id = chuck.listen_for_global_event("response", on_response, listen_forever=True)

# Trigger notes from Python
for note in [60, 64, 67, 72]:  # C major chord
    chuck.set_global_int("noteValue", note)
    chuck.signal_global_event("trigger")
    run_cycles(10)

# Stop listening
chuck.stop_listening_for_global_event("response", listener_id)

Shred Management & Introspection

import numchuck
import numpy as np

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_INPUT_CHANNELS, 2)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()
chuck.start()

# Spork multiple shreds
code = "while(true) { 100::ms => now; }"
success1, ids1 = chuck.compile_code(code)
success2, ids2 = chuck.compile_code(code)
success3, ids3 = chuck.compile_code(code)

# Introspect running shreds
all_ids = chuck.get_all_shred_ids()
print(f"Running shreds: {all_ids}")

for shred_id in all_ids:
    info = chuck.get_shred_info(shred_id)
    print(f"Shred {info['id']}: {info['name']}, running={info['is_running']}")

# Remove specific shred
chuck.remove_shred(ids1[0])
print(f"After removal: {chuck.get_all_shred_ids()}")

# Get next shred ID
next_id = chuck.get_next_shred_id()
print(f"Next shred ID will be: {next_id}")

# Clear all
chuck.clear_vm()
print(f"After clear_vm: {chuck.get_all_shred_ids()}")

Live Coding with replace_shred()

import numchuck
import numpy as np

chuck = numchuck.ChucK()
chuck.set_param(numchuck.PARAM_SAMPLE_RATE, 44100)
chuck.set_param(numchuck.PARAM_INPUT_CHANNELS, 2)
chuck.set_param(numchuck.PARAM_OUTPUT_CHANNELS, 2)
chuck.init()
chuck.start()

# Start with one sound
code_v1 = '''
SinOsc s => dac;
440 => s.freq;
while(true) { 1::samp => now; }
'''
success, ids = chuck.compile_code(code_v1)
original_id = ids[0]

# ... play for a while ...

# Hot-swap to different sound
code_v2 = '''
TriOsc t => dac;
330 => t.freq;
0.5 => t.gain;
while(true) { 1::samp => now; }
'''
new_id = chuck.replace_shred(original_id, code_v2)
print(f"Replaced shred {original_id} with {new_id}")

Capturing ChucK Console Output

import numchuck

chuck = numchuck.ChucK()
chuck.init()

# Capture chout (console output)
output_log = []
chuck.set_chout_callback(lambda msg: output_log.append(msg))

# Capture cherr (error output)
error_log = []
chuck.set_cherr_callback(lambda msg: error_log.append(msg))

# Run code that prints
chuck.compile_code('''
    <<< "Hello from ChucK!" >>>;
    <<< "Value:", 42 >>>;
''')

# Check captured output
print("ChucK output:", output_log)

Requirements

• Python 3.8+
• CMake 3.15+
• C++17 compatible compiler
• macOS: Xcode with CoreAudio/CoreMIDI frameworks
• numpy (for audio processing)

Development

# Build
make build

# Run tests
make test

# Clean build artifacts
make clean

What's with the name?

numchuck initially started off as pychuck. When I posted in the Chuck Discord about an earlier iteration of the project, David Braun suggested the name NumChuck, which fits much better with the project’s use of NumPy.

Nonetheless, the inertia of the initial name held until I went to publish the project on PyPI and discovered that there was already a pychuck project whose purpose is to implement (rather than wrap) the Chuck language in Python—-which is, in hindsight, a much stronger claim to the name.

Luckily, the name numchuck was available, allowing this project to narrowly avoid an unnecessary naming showdown.

License

numchuck is licensed under the GNU General Public License v3.0

Credits

• ChucK: Ge Wang, Perry Cook, and the ChucK team
• nanobind: Wenzel Jakob and contributors
• David Braun: For suggesting the name, numchuck!
• claude-code: Anthropic