Air Synthesizer with Color Tracking in 10 Min

What is this project about?

Build an Air Synthesizer that plays musical instruments using real-time color tracking. Move a colored ball through different zones on camera, and each zone triggers a different synthesizer note. Change instruments on the fly—from piano to drums and beyond.

Why did we decide to make it?

Creating a color-tracking musical instrument traditionally requires computer vision libraries, audio synthesis, zone detection algorithms, and real-time processing. Using Grablo's visual blocks, all of this complexity disappears—no coding needed.

What You'll Build

A complete air synthesizer featuring:

• Real-time color ball tracking
• 5 playable zones
• Multiple instruments via Sound Font
• Dynamic color range adjustment
• Instrument selection through Bank/Preset

Demo

Quick Start

• Install software: Download and install Grablo on your Raspberry Pi
• Set up hardware: Connect camera and speaker
• Get this project: Project Link
• Open Grablo app: On your desktop or mobile browser
• Hit RUN: Connect to your Raspberry Pi and start playing!
• Adjust colors: Use Color Picker to match your colored ball
• Change instruments: Modify Bank and Preset values

💡 Want to build it yourself? Continue to Build Process

Build Process

Dashboard

Create Project & Dashboard

• Go to https://app.grablo.co
• Click "Create Project"
• Name your project
• Create a new dashboard

Add Widgets

• Camera Widget: Select your camera to display live video feed
• Color Picker Widget × 2: Create "Start Color" and "End Color" variables for tracking range
• Input Widget × 2: Create "Bank" and "Preset" variables for instrument selection

Logic

Control 1: Start Camera

Start the camera when the project begins.

• Condition (Once): Runs once at project start
• Action (AI Camera): Create camera, set Orientation to Horizontal Flip, Command to Start, add Color Tracking for 5 Zones

Control 2-6: Play Notes

Play synthesizer notes when colored object enters each zone.

• Condition (Compare): ZoneDetected = True, Option = Rising Edge
• Action (Synthesizer): Create synthesizer, Command = Note On, Note = C3-G3 (48-55)

Control 7: Instrument Selection

Change instruments when Bank or Preset value changes.

• Condition (On Change): Bank or Preset variable, Operator = OR
• Action (Synthesizer): Command = Set Instrument, assign Bank and Preset variables

That's It!

Congratulations! You've built a complete air synthesizer using visual blocks and zero lines of code.

Expected Results

When you run your project:

• Camera view appears: 5 zones displayed at the bottom
• Move colored ball into Zone 1: Plays C3 note
• Move through different zones: Each zone plays its assigned note
• Change Bank to 128: Switches to drum sounds
• Adjust Color Picker: Fine-tune tracking for your ball color

Hardware Setup

Camera Options:

• Raspberry Pi Camera Module (CSI)
• USB Camera

Speaker Options:

• 3.5mm audio jack
• USB audio adapter
• Bluetooth speaker

Colored Ball Tips:

• Use bright colors: orange, green, or pink work best
• Attach to a stick for easier control
• Ping pong balls are lightweight and track well

Video Tutorial

Watch the complete build process in action:

What's Next?

Expand your project:

• Add more zones for a full octave
• Create a duet mode with two different colored balls
• Add visual feedback on the dashboard when notes play

Troubleshooting

No sound:

• Check speaker connection
• Verify Bank and Preset values are valid
• Try Bank = 0, Preset = 0 for piano

Color not tracking:

• Adjust Start/End Color range in Color Picker
• Use HSV tab and adjust H value for fine-tuning
• Ensure lighting is consistent
• Avoid wearing clothes that match ball color

Tracking multiple objects:

• Increase Min Area value to ignore small noise
• Use a more unique color for the ball
• Improve lighting conditions

Notes playing multiple times:

• Verify Rising Edge option is set in conditions
• Check that zones don't overlap

Sound Font Resources

• Polyphone (Sound Font Editor): https://www.polyphone.io/
• Sound Font used in this project: https://musical-artifacts.com/artifacts/7293

Resources & Support

• Website: https://grablo.co
• Web App: https://app.grablo.co
• Docs: https://doc.grablo.co
• Support: support@grablo.co