Source Code

FL Studio Python Scripting

Complete reference for FL Studio's Python API: MIDI controller scripting (14 modules, 427+ functions), piano roll note manipulation, Edison audio editing, and FLP file parsing with PyFLP.

Quick Start

Requirements

FL Studio 20.8.4+, Python 3.6+

Check API Version

import general
print(f"API Version: {general.getVersion()}")

Script Installation

Place scripts in Shared\Python\User Scripts folder.

Three Scripting Contexts

1. MIDI Controller Scripting

Purpose: Control FL Studio through hardware MIDI controllers and send feedback to devices. Runs: Continuously while FL Studio is open. Available modules: transport, mixer, channels, arrangement, patterns, playlist, device, ui, general, plugins, screen, launchMapPages, utils, callbacks

Entry points:

def OnInit():
    """Called when script starts."""
    pass

def OnDeInit():
    """Called when script stops."""
    pass

def OnMidiMsg(msg):
    """Called for incoming MIDI messages."""
    pass

def OnControlChange(msg):
    """Called for CC messages."""
    pass

def OnNoteOn(msg):
    """Called for note-on messages."""
    pass

def OnRefresh(flags):
    """Called when FL Studio state changes."""
    pass

2. Piano Roll Scripting

Purpose: Manipulate notes and markers in the piano roll editor. Runs: Once when user invokes through Scripts menu. Available modules: flpianoroll, enveditor

import flpianoroll
score = flpianoroll.score
for note in score.notes:
    note.velocity = 0.8  # Set all velocities to 80%

3. Edison Audio Scripting

Purpose: Edit and process audio samples in Edison. Runs: Once within Edison's context. Available modules: enveditor

API Module Reference Map

Navigate to the appropriate reference file based on what you need to control. Read these files ONLY when you need specific API signatures.

Core Workflow Modules

Module	Functions	What It Controls	Reference
transport	20	Play, stop, record, position, tempo, looping	api-transport.md
mixer	69	Track volume/pan/mute/solo, EQ, routing, effects	api-mixer.md
channels	48	Channel rack, grid bits, step sequencer, notes	api-channels.md

Arrangement Modules

Module	Functions	What It Controls	Reference
arrangement + patterns	9 + 25	Markers, time, pattern control, groups	api-arrangement-patterns.md
playlist	41	Playlist tracks, live mode, performance, blocks	api-playlist.md

Device & Communication

Module	Functions	What It Controls	Reference
device	34	MIDI I/O, sysex, dispatch, hardware refresh	api-device.md

UI & Application Control

Module	Functions	What It Controls	Reference
ui + general	71 + 24	Windows, navigation, undo/redo, version, snap	api-ui-general.md

Plugins

Module	Functions	What It Controls	Reference
plugins	13	Plugin parameters, presets, names, colors	api-plugins.md

Specialized Hardware Display

Module	Functions	What It Controls	Reference
screen + launchMapPages	9 + 12	AKAI Fire screen, launchpad page management	api-screen-launchmap.md

Utilities, Constants & MIDI Reference

Module	Functions	What It Controls	Reference
utils + constants	21	Color conversion, math, note names, MIDI tables	api-utils-constants.md

Callbacks & FlMidiMsg

Module	Functions	What It Controls	Reference
callbacks	26	All callback functions, FlMidiMsg class, event flow	api-callbacks.md

Non-MIDI Scripting APIs

Piano Roll & Edison

Note, Marker, ScriptDialog, score classes for piano roll manipulation plus Edison enveditor utilities. See piano-roll-edison.md

FLP File Parsing (PyFLP)

External library for reading/writing .flp project files without FL Studio running. Batch processing, analysis, automated generation. See pyflp.md

Common Patterns

Minimal MIDI Controller Skeleton

# name=My Controller
# url=https://example.com

import device
import mixer
import transport

def OnInit():
    if device.isAssigned():
        print(f"Connected: {device.getName()}")

def OnDeInit():
    print("Script shut down")

def OnControlChange(msg):
    if msg.data1 == 7:  # Volume CC
        mixer.setTrackVolume(mixer.trackNumber(), msg.data2 / 127.0)
        msg.handled = True

def OnNoteOn(msg):
    track = msg.data1 % 8
    mixer.setActiveTrack(track)
    msg.handled = True

def OnRefresh(flags):
    pass  # Update hardware display here

Key Pattern: Always Check Device Assignment

def OnInit():
    if not device.isAssigned():
        print("No output device linked!")
        return
    # Safe to use device.midiOutMsg() etc.

Key Pattern: Mark Events as Handled

def OnControlChange(msg):
    if msg.data1 == 7:
        mixer.setTrackVolume(0, msg.data2 / 127.0)
        msg.handled = True  # Prevent FL Studio from also processing this

Key Pattern: Send Feedback to Hardware

def OnRefresh(flags):
    if device.isAssigned():
        # Update volume fader LED
        vol = int(mixer.getTrackVolume(0) * 127)
        device.midiOutMsg(0xB0, 0, 7, vol)

For complete examples (MIDI learn, scale enforcer, LED feedback, batch quantization, sysex handling, performance monitoring, automation engine, debugging): See examples-patterns.md

Best Practices

Performance

Cache module references at top level (import once)
Avoid tight loops in MIDI callbacks (keep under 10ms)
Batch UI updates; use device.directFeedback() for controller echo

Hardware Integration

Always check device.isAssigned() before device functions
Implement two-way sync for all controls (send feedback on state change)
Test on real hardware (virtual ports behave differently)

Code Organization

Separate MIDI mapping from business logic (use a controller class)
Keep callbacks responsive; offload complex work
Handle edge cases: invalid indices, missing devices, out-of-range values

Troubleshooting

Script Not Receiving MIDI

Check device.isAssigned() returns True
Verify MIDI input port in FL Studio MIDI Settings
Ensure callback functions are defined at module level (not nested)
Check MIDI message status bytes match expected values

Piano Roll Script Not Working

Verify script is in Shared\Python\User Scripts folder
Ensure a pattern is open in piano roll before running
Access notes via flpianoroll.score.notes

Performance Issues

Avoid complex calculations inside OnIdle() (called every ~20ms)
Don't repeatedly query values that haven't changed
Use device.setHasMeters() only if peak meters are needed

FAQ

Double-click detection: Use device.isDoubleClick(index)
Inter-script communication: Use device.dispatch(ctrlIndex, message)
LED control: device.midiOutMsg(0x90, 0, note, velocity) for note-on LEDs
processMIDICC vs OnControlChange: Use On* callbacks for modern code
GUI access: Limited through ui module; full UI automation not available
Multiple devices: Check device.getName() to identify, handle per-port

Resources

Official FL Studio API: https://www.image-line.com/fl-studio/modules/python-scripting/
PyFLP GitHub: https://github.com/demberto/PyFLP
API Functions: 427+ across 14 modules | Last Updated: 2025

flstudio-scripting