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

Arrangement Modules

Device & Communication

UI & Application Control

Plugins

Specialized Hardware Display

Utilities, Constants & MIDI Reference

Callbacks & FlMidiMsg

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](references/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](references/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](references/examples-patterns.md)

Best Practices

Performance

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

Hardware Integration

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

Code Organization

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

Troubleshooting

Script Not Receiving MIDI

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

Piano Roll Script Not Working

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

Performance Issues

1. Avoid complex calculations inside OnIdle() (called every ~20ms)
2. Don't repeatedly query values that haven't changed
3. 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