Custom Transform Logic

Advanced topic: Building custom MIDI processing beyond built-in nodes

Overview

Neurode MIDI uses Neuroscript v3 (Rust) as the canonical way to express routing/transforms. Visual authoring compiles to Neuroscript, and scripts are compiled off realtime threads into deterministic programs.

While Neurode MIDI provides built-in routing/transformation primitives, you may need custom logic for:

• Algorithmic composition — Generative patterns, arpeggios, chord progressions
• Adaptive processing — Context-aware transformations based on musical analysis
• Hardware integration — Specialized controller mappings unique to your gear
• Experimental effects — Custom algorithms not covered by standard nodes

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Neuroscript (Recommended)

Neuroscript is a musician-focused DSL optimized for common MIDI operations.

When to Use

• Standard transforms (velocity shaping, filtering, remapping)
• Readable, maintainable scripts for musicians
• Fast prototyping without extensive code

Example: Custom Velocity Curve

# Compress loud notes, boost quiet notes
when vel > 100: event(vel = clamp(vel, 90, 110))
when vel < 40: event(vel = clamp(vel + 20, 1, 127))

Example: Conditional Layering

# Soft notes go to pad, loud notes to lead
when vel < 60: event(ch = 3)
when vel >= 60: event(ch = 2)

Limitations

• No dynamic memory allocation or unbounded loops
• Deterministic per-event execution
• Timing control limited to send/emit with durations

Full Reference: Neuroscript Language

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Best Practices

1. Start with Built-In Nodes

Before writing custom scripts, check if built-in nodes can achieve the same result:

Prefer built-in transforms (filtering, channel remap, velocity shaping) when they exist.

2. Keep Scripts Small and Focused

Good (focused script):

# Single responsibility: boost quiet notes
when vel < 50: event(vel = clamp(vel + 10, 1, 127))

If a script grows beyond ~10–15 lines, consider splitting it into separate routes/presets or refactoring into smaller, commented sections.

3. Test Scripts in Isolation

Use the Playground Simulator to test scripts before embedding in routes:

1. Write script
2. Test with sample MIDI events
3. Verify output
4. Apply the script to your route/preset

4. Profile Script Performance

Add Monitor nodes before/after script nodes to measure latency:

[Input] → [Monitor A] → [Script] → [Monitor B] → [Output]

If latency exceeds 1ms consistently, consider:

• Simplifying logic
• Using built-in nodes

5. Handle Edge Cases

MIDI events can be unpredictable — always validate:

when type == note: event(note = clamp(note + 12, 0, 127))

6. Comment Your Logic

Future you (or other musicians) will thank you:

# Humanize velocity slightly (note events only)
when type == note: event(vel = clamp(vel + 4, 1, 127))