cycsound

Cython bindings for the Csound 6.x API.

Overview

cycsound is a Cython wrapper for the Csound audio synthesis library, providing Python bindings for the csound.h C API. It offers an alternative to the default ctypes-based ctcsound.py wrapper included with Csound.

Features

• 98% API coverage of the Csound C API (216/219 functions)
• Context manager support for automatic resource cleanup
• GIL release for all blocking operations (enables true multi-threading)
• Static linking support on macOS (standalone wheels without Csound installation)
• Platform support: macOS, Linux, Windows
• CLI for common operations (play, render, check, info, eval)

Installation

pip install cycsound

Building From Source

Prerequisites:

• Python >= 3.9
• Csound 6.x installed:
  • macOS: CsoundLib64.framework in /Library/Frameworks/
  • Linux: libcsound64-dev package
  • Windows: Csound6_x64 in C:/Program Files/

# Clone the repository
git clone https://github.com/yourusername/cycsound.git
cd cycsound

# Install in development mode
make sync

# Or install directly
pip install .

Building Wheels

# Dynamic linking (requires Csound at runtime)
make wheel

# Static linking - standalone wheel (macOS only)
make wheel-static

Command-Line Interface

cycsound includes a CLI for common Csound operations:

# Play a CSD file
cycsound play myscore.csd

# Render to audio file
cycsound render myscore.csd                    # Creates myscore.wav
cycsound render -o output.wav myscore.csd      # Specify output file
cycsound render -f flac -r 48000 myscore.csd   # FLAC format, 48kHz

# Validate CSD syntax
cycsound check myscore.csd

# Show Csound version info
cycsound info
cycsound info -v    # Verbose output

# Get help
cycsound --help
cycsound play --help

CLI Commands

Command	Description
play <file>	Play CSD file in real-time
render <file>	Render CSD to audio file
check <file>	Validate CSD syntax
info	Show Csound version
eval <code>	Evaluate orchestra code

Common Options

Option	Description
-q, --quiet	Suppress output
-o, --output	Output file/device
-h, --help	Show help

Quick Start

import cycsound

# Using context manager (recommended)
with cycsound.Csound() as cs:
    cs.set_option("-odac")  # Real-time audio output
    cs.set_option("-d")     # Suppress displays
    cs.compile_orc("""
sr = 44100
ksmps = 32
nchnls = 2
0dbfs = 1

instr 1
    asig oscil 0.5, 440
    outs asig, asig
endin
""")
    cs.read_score("i1 0 2")
    cs.run()  # Performs entire score
# cleanup() called automatically on exit

# Or with manual control
with cycsound.Csound() as cs:
    cs.compile_csd("myscore.csd")
    cs.start()
    while not cs.perform_ksmps():
        # Process each k-cycle
        pass

API Reference

Module-level Functions

Function	Description
get_version()	Returns Csound version (e.g., 6180 for 6.18.0)
get_api_version()	Returns API version
get_size_of_myflt()	Returns size of MYFLT type (4 or 8)
initialize(flags=0)	Initialize Csound library (rarely needed)
set_opcode_dir(path)	Set opcode directory override

Csound Class

Core methods for audio synthesis:

# Context manager support
with cycsound.Csound() as cs:
    # ... use cs ...
# cleanup() called automatically

# Compilation
cs.compile_orc(orc_string)      # Compile orchestra code
cs.compile_csd(filename)        # Compile CSD file
cs.compile_csd_text(csd_string) # Compile CSD from string
cs.read_score(score_string)     # Read score events

# Performance
cs.run()             # Perform entire score (convenience method)
cs.start()           # Prepare for performance
cs.perform()         # Perform entire score (blocks)
cs.perform_ksmps()   # Perform one control period
cs.perform_buffer()  # Perform one buffer
cs.stop()            # Stop performance
cs.cleanup()         # Close audio/MIDI devices
cs.reset()           # Reset for new performance

# Configuration
cs.set_option(option)           # Set command-line option
cs.get_sr() / cs.get_kr()       # Get sample/control rate
cs.get_ksmps() / cs.get_nchnls() # Get ksmps/channels

# Channels
cs.set_control_channel(name, value)
cs.get_control_channel(name)
cs.set_string_channel(name, value)
cs.get_string_channel(name)

Enums

# Status codes (return values from Csound operations)
cycsound.Status.SUCCESS        # 0 - Operation succeeded
cycsound.Status.ERROR          # -1 - General error
cycsound.Status.INITIALIZATION # -2 - Initialization error
cycsound.Status.PERFORMANCE    # -3 - Performance error
cycsound.Status.MEMORY         # -4 - Memory allocation error
cycsound.Status.SIGNAL         # -5 - Signal received

# File types
cycsound.FileType.WAVE         # WAV audio
cycsound.FileType.FLAC         # FLAC audio
cycsound.FileType.OGG          # OGG Vorbis audio
cycsound.FileType.UNIFIED_CSD  # Csound CSD file
cycsound.FileType.STD_MIDI     # Standard MIDI file
# ... and 60+ more file type constants

# Message types
cycsound.Msg.DEFAULT   # Standard message
cycsound.Msg.ERROR     # Error message
cycsound.Msg.WARNING   # Warning message

# Message colors
cycsound.Color.FG_RED  # Foreground colors
cycsound.Color.FG_GREEN
cycsound.Color.FG_BOLD # Text attributes

Development

Setup

# Initial setup
make sync

# Rebuild after code changes
make build

# Run tests
make test          # All tests
make test-cli      # CLI tests only

Available Make Targets

Target	Description
make / make build	Build/rebuild the extension
make sync	Initial environment setup
make test	Run test suite
make wheel	Build wheel (dynamic linking)
make wheel-static	Build standalone wheel (macOS)
make release	Build static wheels for all Python versions
make check	Check distribution with twine
make publish	Publish to PyPI
make publish-test	Publish to TestPyPI
make clean	Remove build artifacts
make help	Show all targets

Static Build Requirements (macOS)

For make wheel-static, install dependencies via Homebrew:

brew install libsndfile flac opus libvorbis libogg mpg123 lame

Rationale

This project provides an alternative to the default ctypes-based wrapper. Cython offers several advantages over ctypes:

• Better performance for tight loops
• Direct C-level access to Csound internals
• Ability to release the GIL for true multi-threading
• Static linking for self-contained distribution

For more details, see this comparison of wrapping approaches.

Status

• Wrap enough to play arbitrary CSD files
• Build static variant as wheel (macOS only)
• 98% coverage of csound.h API (216/219 functions)
• GIL release for all blocking operations
• scikit-build-core based build system
• Context manager support
• Test suite (36 tests: core API, CLI, channels, threading, enums)
• CI/CD with cibuildwheel (GitHub Actions)
• Complete wrapping of csound.h (remaining: 3 va_list callbacks)
• Include plugin support in wheel
• Feature parity with ctcsound.py

Related Projects

• ctcsound - Official ctypes-based Python wrapper
• Csound - The Csound audio synthesis system

License

See LICENSE file.