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py2max

Python 3.9+ License: MIT

A pure Python library for offline generation of Max/MSP patcher files (.maxpat, .maxhelp, .rbnopat).

If you are looking for Python 3 externals for Max/MSP, check out the py-js project.

Installation

pip install py2max

For the browser-based live editor and remote REPL, install the companion py2max-server package:

pip install py2max-server

For development:

git clone https://github.com/shakfu/py2max.git
cd py2max
uv sync
source .venv/bin/activate

Quick Start

from py2max import Patcher

p = Patcher('my-synth.maxpat')
osc = p.add('cycle~ 440')
gain = p.add('gain~')
dac = p.add('ezdac~')
p.link(osc, gain)
p.link(gain, dac)
p.save()

That's it! Open my-synth.maxpat in Max to see your patch.

Features

Core Capabilities

  • Offline Patch Generation - Create Max patches programmatically without Max running
  • Round-trip Conversion - Load, modify, and save existing .maxpat files
  • Max for Live (.amxd) - Read/write binary .amxd device files with presentation-mode helpers
  • Universal Object Support - Works with any Max/MSP/Jitter object
  • Fully typed - Passes mypy --strict; no runtime dependencies
  • High Test Coverage - 420+ tests ensure reliability

Max for Live (.amxd)

Generate Max for Live devices directly. Patcher.save() / Patcher.from_file() auto-detect the .amxd extension and read/write the binary device format, byte-for-byte compatible with Max-exported devices.

from py2max import Patcher

# device_type: "audio_effect" (default), "instrument", or "midi_effect"
p = Patcher('gain.amxd', device_type='audio_effect')
p.enable_presentation(devicewidth=120)        # render Ableton's device strip

plugin = p.add_textbox('plugin~')             # audio in from Live
gain = p.add('live.gain~', maxclass='live.gain~')
plugout = p.add_textbox('plugout~')           # audio back to Live
gain.add_to_presentation([20, 20, 60, 136])   # show the fader in the device

p.add_line(plugin, gain, outlet=0, inlet=0)
p.add_line(gain, plugout, outlet=0, inlet=0)
p.save()                                       # writes a binary .amxd

Helpers: Patcher.enable_presentation(devicewidth=...), Box.add_to_presentation([x, y, w, h]) (rejects M4L infrastructure objects and rounds fractional coordinates), and Patcher.enforce_integer_coords(). M4L binary helpers live in py2max.m4l.

Interactive Server (separate package)

Real-time browser-based patch editing with bidirectional sync lives in the companion py2max-server package, so the core library stays small and offline:

pip install py2max-server
py2max-server serve my-patch.maxpat
# Opens browser at http://localhost:8000

Features:

  • Drag objects, draw connections visually
  • Three layout engines: WebCola, ELK, and Dagre
  • Auto-save with debouncing
  • Navigate into subpatchers
  • REPL mode for Python interaction

SVG Preview

Generate high-quality SVG previews without Max:

py2max preview my-patch.maxpat --open
p = Patcher('synth.maxpat')
# ... add objects ...
p.to_svg('synth.svg', title="My Synth", show_ports=True)

Layout Managers

Five built-in layout strategies:

Layout Description
grid Connection-aware clustering with configurable flow
flow Signal flow-based hierarchical positioning
columnar Controls -> Generators -> Processors -> Outputs
matrix Signal chains in columns, categories in rows
horizontal/vertical Simple grid layouts 
p = Patcher('patch.maxpat', layout='flow', flow_direction='vertical')
# Add objects and connections...
p.optimize_layout()  # Arrange based on signal flow
p.save()

MaxRef Integration

Access documentation for 1157 Max objects:

p = Patcher('demo.maxpat')
cycle = p.add('cycle~ 440')

print(cycle.help())  # Full documentation
print(f"Inlets: {cycle.get_inlet_count()}")
print(f"Outlets: {cycle.get_outlet_count()}")

Connection Validation

Optional validation catches wiring errors:

p = Patcher('patch.maxpat', validate_connections=True)
osc = p.add('cycle~ 440')
gain = p.add('gain~')

p.link(osc, gain)              # Valid
p.link(osc, gain, outlet=5)    # Raises InvalidConnectionError

Semantic IDs

Human-readable object IDs for easier debugging:

p = Patcher('patch.maxpat', semantic_ids=True)

osc1 = p.add('cycle~ 440')   # ID: 'cycle_1'
osc2 = p.add('cycle~ 220')   # ID: 'cycle_2'
gain = p.add('gain~')        # ID: 'gain_1'

# Find by semantic ID
osc = p.find_by_id('cycle_1')

SQLite Database

Query Max object metadata efficiently:

from py2max import MaxRefDB

db = MaxRefDB()  # Auto-cached on first use
print(len(db))   # 1157 objects

if 'cycle~' in db:
    info = db['cycle~']
    print(info['digest'])

# Search and filter
results = db.search('filter')
msp_objects = db.by_category('MSP')

Usage Examples

Basic Patch Creation

from py2max import Patcher

p = Patcher('my-patch.maxpat')
osc = p.add('cycle~ 440')
gain = p.add('gain~')
dac = p.add('ezdac~')

p.link(osc, gain)
p.link(gain, dac)
p.link(gain, dac, inlet=1)  # Stereo
p.save()

Loading and Modifying Patches

p = Patcher.from_file('existing.maxpat')

# Find and modify objects
for box in p.find_by_text('cycle~'):
    print(f"Found oscillator: {box.id}")

p.save_as('modified.maxpat')

Subpatchers

p = Patcher('main.maxpat')
sbox = p.add_subpatcher('p mysub')
sp = sbox.subpatcher

# Build the subpatcher
inlet = sp.add('inlet')
gain = sp.add('gain~')
outlet = sp.add('outlet')
sp.link(inlet, gain)
sp.link(gain, outlet)

# Connect in main patcher
osc = p.add('cycle~ 440')
dac = p.add('ezdac~')
p.link(osc, sbox)
p.link(sbox, dac)
p.save()

Object Search

p = Patcher.from_file('complex-patch.maxpat')

# Find by ID
obj = p.find_by_id('obj-5')

# Find by text content
oscillators = p.find_by_text('cycle~')

# Find by object type
messages = p.find_by_type('message')

Command Line Interface

Patch Management

# Create new patch from template
py2max new demo.maxpat --template stereo

# Show patch info
py2max info demo.maxpat

# Generate SVG preview
py2max preview demo.maxpat --open

# Optimize layout
py2max optimize demo.maxpat --layout flow

# Validate connections
py2max validate demo.maxpat

Interactive Server

Provided by the separate py2max-server package (pip install py2max-server):

# Start server with browser editing
py2max-server serve my-patch.maxpat

# With REPL in same terminal
py2max-server serve my-patch.maxpat --repl

MaxRef Database

# Show cache status
py2max db cache location

# Create category-specific database
py2max db create msp.db --category msp

# Search objects
py2max db search maxref.db "oscillator" -v

# Query specific object
py2max db query maxref.db cycle~ --json

Converters

# Convert .maxpat to Python code
py2max convert maxpat-to-python patch.maxpat output.py

# Lookup object documentation
py2max maxref cycle~ --json

Use Cases

  • Scripted patch generation - Automate repetitive patch creation
  • Batch processing - Modify multiple .maxpat files programmatically
  • Parametric patches - Generate variations from configuration files
  • Test generation - Create .maxhelp files during external development
  • Container population - Prepopulate coll, dict, table objects with data
  • Generative patching - Algorithmic patch creation
  • CI/CD integration - SVG previews for documentation and version control

Testing

make test        # Run all tests
make typecheck   # Type checking with mypy
make lint        # Linting with ruff
make docs        # Build documentation

Design Notes

The .maxpat JSON format maps directly to three Python classes:

  • Patcher - The patch container with boxes and patchlines
  • Box - Individual Max objects
  • Patchline - Connections between boxes

All classes are extendable via **kwargs, allowing any Max object configuration. The add_textbox() method handles most objects, with specialized methods (add_subpatcher(), add_coll(), etc.) for objects requiring extra configuration.

Caveats

  • Max doesn't refresh from file when open - close and reopen to see changes, or use py2max-server serve (from the separate py2max-server package) for live editing
  • For tilde variants, use the _tilde suffix: p.add_gen() vs p.add_gen_tilde()
  • API docs in progress - see CLAUDE.md for comprehensive usage

Examples

The tests/examples/ directory contains working, tested examples organized by topic (see its README):

  • quickstart/basic_patch.py - Simple oscillator patch
  • tutorial/signal_processing_chain.py - Complex audio processing chain
  • tutorial/generative_music.py - Generative music system with patterns
  • layout/grid_layout_examples.py - Grid layout with clustering
  • advanced/data_containers.py - Tables, collections, and dictionaries
  • api/patcher_api_examples.py - Patcher API reference examples

External usage:

Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines.

git clone https://github.com/shakfu/py2max.git
cd py2max
uv sync
source .venv/bin/activate
make test  # Verify setup

License

MIT License. See LICENSE for details.

Credits

  • HOLA algorithm: Kieffer, Dwyer, Marriott, Wybrow (IEEE 2016)
  • NetworkX: Hagberg, Schult, Swart (SciPy 2008)
  • Graph drawing techniques: Gansner, Koutsofios, North, Vo (IEEE 1993)

About

A python library for offline generation of Max/MSP patcher (.maxpat) files.

shakfu.github.io/py2max/

Topics

python max python3 maxmsp

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License

MIT license

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