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Audio Reactive Visualization Example

examples/Audio/simple/README.md

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Audio Reactive Visualization Example

This example demonstrates advanced audio reactive visualization capabilities using FastLED. It processes real-time audio input and creates stunning visual effects synchronized to music.

Features

Visualization Modes

  1. Spectrum Analyzer - Classic frequency spectrum display with customizable colors
  2. Waveform - Real-time audio waveform visualization
  3. VU Meter - Traditional volume unit meter with RMS and peak indicators
  4. Spectrogram - Scrolling frequency analysis over time
  5. Combined - Split-screen showing both spectrum and waveform
  6. Reactive Patterns - Dynamic patterns that respond to audio energy and beats

Audio Processing

  • Real-time FFT - Fast Fourier Transform for frequency analysis
  • Beat Detection - Automatic beat detection with adjustable sensitivity
  • Auto Gain Control (AGC) - Automatically adjusts to varying audio levels
  • Noise Floor Filtering - Removes background noise for cleaner visuals
  • Attack/Decay/Sustain - Professional audio envelope controls

Visual Controls

  • Multiple Color Palettes - Heat, Rainbow, Ocean, Forest, Lava, Cloud, Party
  • Mirror Mode - Creates symmetrical displays
  • Brightness Control - Adjustable LED brightness
  • Fade Effects - Smooth transitions with adjustable fade time
  • Color Animation - Animated color cycling with speed control
  • Smoothing - Optional smoothing for less jittery displays

Advanced Features

  • Frequency Band Analysis - 8-band frequency analyzer for detailed audio analysis
  • FFT Smoothing - Temporal smoothing of frequency data
  • Logarithmic Scale - Optional log scale for frequency display
  • Freeze Frame - Pause the visualization at any moment
  • Frame Advance - Step through frozen frames

UI Controls

Main Controls

  • Enable Audio Reactive Mode - Master on/off switch for audio processing
  • Visualization Mode - Dropdown to select visualization type

Audio Processing Group

  • Fade Time - How quickly levels decay (0-4 seconds)
  • Attack Time - How quickly levels rise (0-4 seconds)
  • Output Smoothing - Final output smoothing (0-2 seconds)
  • Audio Gain - Manual gain adjustment (0.1-5.0)
  • Noise Floor - Background noise threshold (-80 to -20 dB)

Visual Controls Group

  • Fade to Black - Trail/persistence effect (0-50)
  • Brightness - LED brightness (0-255)
  • Color Speed - Animation speed (0.1-5.0)
  • Color Palette - Choose from 7 palettes
  • Mirror Mode - Enable symmetrical display
  • Smoothing - Enable temporal smoothing

FFT Controls Group

  • Min Frequency - Lower frequency bound (20-1000 Hz)
  • Max Frequency - Upper frequency bound (1000-20000 Hz)
  • Logarithmic Scale - Use log scale for frequency
  • FFT Smoothing - Smoothing factor (0-0.95)

Advanced Controls Group

  • Freeze Frame - Pause visualization
  • Advance Frame - Step forward when frozen
  • Beat Detection - Enable beat detection
  • Beat Sensitivity - Beat detection threshold (0.5-3.0)
  • Auto Gain Control - Enable automatic gain adjustment

Hardware Setup

LED Configuration

  • Default: 128x128 LED matrix (16,384 LEDs)
  • Downscaled to 64x64 for output (4,096 LEDs)
  • Data pin: GPIO 3 (configurable)
  • LED type: WS2812B (Neopixel)

Audio Input

The example uses the FastLED audio system which can accept input from:

  • Microphone (real-time audio capture)
  • Audio file playback
  • System audio (on supported platforms)

Usage

  1. Basic Operation

    • Upload the sketch to your controller
    • Connect your LED matrix
    • Provide audio input
    • Use the web UI to control visualization

  2. Optimizing for Your Setup

    • Adjust the noise floor if visualization is too sensitive/insensitive
    • Use AGC for varying audio levels
    • Tune beat sensitivity for your music style
    • Experiment with different color palettes and speeds

  3. Performance Tips

    • Reduce matrix size for slower controllers
    • Disable smoothing for more responsive display
    • Use simpler visualization modes for lower CPU usage

Code Structure

Main Components

  1. Audio Processing Pipeline

    cpp
    AudioSample → FFT → Band Analysis → Beat Detection → Visualization

  2. Visualization Functions

    • drawSpectrumAnalyzer() - Frequency spectrum bars
    • drawWaveform() - Audio waveform display
    • drawVUMeter() - Volume meter visualization
    • drawSpectrogram() - Time-frequency plot
    • drawReactivePatterns() - Beat-reactive patterns

  3. Audio Analysis Classes

    • MaxFadeTracker - Smooth peak tracking with attack/decay
    • BeatDetector - Energy-based beat detection
    • FrequencyBandAnalyzer - 8-band frequency analysis

Customization

Adding New Visualizations

  1. Create a new draw function
  2. Add it to the visualization mode dropdown
  3. Add a case in the main switch statement

Modifying Color Palettes

Edit the getCurrentPalette() function to add custom palettes.

Adjusting Frequency Bands

Modify the FrequencyBandAnalyzer constructor to change band boundaries.

Troubleshooting

  • No visualization: Check audio input and ensure "Enable Audio Reactive Mode" is on
  • Too dim/bright: Adjust brightness control
  • Choppy animation: Increase smoothing or reduce matrix size
  • No beat detection: Adjust beat sensitivity or check audio levels
  • Visualization too sensitive: Increase noise floor value

Memory Requirements

This example requires significant memory for:

  • Framebuffer: 128×128×3 = 49,152 bytes
  • LED buffer: 64×64×3 = 12,288 bytes
  • Audio buffers and FFT data

Platforms with limited memory may need to reduce the matrix size.