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+/// @file    Audio.ino
+/// @brief   Audio visualization example with XY mapping
+/// @example Audio.ino
+///
+/// This sketch is fully compatible with the FastLED web compiler. To use it do the following:
+/// 1. Install Fastled: `pip install fastled`
+/// 2. cd into this examples page.  
+/// 3. Run the FastLED web compiler at root: `fastled`
+/// 4. When the compiler is done a web page will open.
+
+/*
+This demo is best viewed using the FastLED compiler.
+
+Windows/MacOS binaries: https://github.com/FastLED/FastLED/releases
+
+Python
+
+Install: pip install fastled
+Run: fastled <this sketch directory>
+This will compile and preview the sketch in the browser, and enable
+all the UI elements you see below.
+*/
+
+// #define SIMPLE_EXAMPLE
+
+
+#include <FastLED.h>
+
+#if !SKETCH_HAS_LOTS_OF_MEMORY
+// Platform does not have enough memory
+void setup() {}
+void loop() {}
+#else
+#ifdef SIMPLE_EXAMPLE
+#include "simple/simple.h"
+#else
+#include "advanced/advanced.h"
+#endif
+#endif
@@ -0,0 +1,148 @@
+# Audio Reactive Visualizations
+
+This example demonstrates various audio-reactive visualization modes using FastLED. It processes real-time audio input and creates stunning visual effects synchronized to music.
+
+## Features
+
+### Visualization Modes
+
+1. **Spectrum Bars** - Classic frequency spectrum analyzer with vertical bars
+2. **Radial Spectrum** - Circular frequency visualization radiating from center
+3. **Waveform** - Real-time audio waveform display
+4. **VU Meter** - Traditional volume unit meter with RMS and peak levels
+5. **Matrix Rain** - Audio-reactive digital rain effect
+6. **Fire Effect** - Flame simulation that responds to audio intensity
+7. **Plasma Wave** - Animated plasma patterns modulated by audio
+
+### Audio Processing
+
+- **Real-time FFT Analysis** - Frequency spectrum analysis
+- **Beat Detection** - Automatic beat detection with adjustable sensitivity
+- **Auto Gain Control** - Automatically adjusts to varying audio levels
+- **Noise Floor Filtering** - Removes background noise
+- **Peak Detection** - Tracks audio peaks with smoothing
+
+### Visual Controls
+
+- **7 Color Palettes** - Rainbow, Heat, Ocean, Forest, Party, Lava, Cloud
+- **Brightness Control** - Adjustable LED brightness
+- **Fade Speed** - Control trail/persistence effects
+- **Mirror Mode** - Create symmetrical displays
+- **Beat Flash** - Visual feedback on beat detection
+
+## Hardware Requirements
+
+- **Controller**: ESP32, Teensy, or other platform with sufficient memory
+- **LED Matrix**: 100x100 pixels (10,000 LEDs total)
+- **Memory**: Requires `SKETCH_HAS_LOTS_OF_MEMORY` (not suitable for Arduino UNO)
+- **Audio Input**: Microphone or line-in audio source
+
+## Wiring
+
+```
+LED Matrix:
+- Data Pin: GPIO 3 (configurable via LED_PIN)
+- Power: 5V (ensure adequate power supply for 10,000 LEDs!)
+- Ground: Common ground with controller
+
+Audio Input:
+- Follow your platform's audio input configuration
+```
+
+## Configuration
+
+### Display Settings
+```cpp
+#define WIDTH 100          // Matrix width
+#define HEIGHT 100         // Matrix height
+#define LED_PIN 3          // Data pin for LEDs
+#define LED_TYPE WS2812B   // LED chipset
+#define COLOR_ORDER GRB    // Color order
+```
+
+### Audio Settings
+```cpp
+#define SAMPLE_RATE 44100  // Audio sample rate
+#define FFT_SIZE 512       // FFT size for frequency analysis
+```
+
+## UI Controls
+
+### Master Controls
+- **Enable Audio** - Toggle audio processing on/off
+- **Visualization Mode** - Select from 7 different modes
+
+### Audio Controls
+- **Audio Gain** - Manual gain adjustment (0.1 - 5.0)
+- **Noise Floor** - Background noise threshold (0.0 - 1.0)
+- **Auto Gain** - Enable automatic gain control
+
+### Visual Controls
+- **Brightness** - LED brightness (0 - 255)
+- **Fade Speed** - Trail effect speed (0 - 255)
+- **Color Palette** - Choose color scheme
+- **Mirror Mode** - Enable symmetrical display
+
+### Beat Detection
+- **Beat Detection** - Enable/disable beat detection
+- **Beat Sensitivity** - Adjust detection threshold (0.5 - 3.0)
+- **Beat Flash** - Enable visual flash on beats
+
+## Usage
+
+1. Upload the sketch to your controller
+2. Connect your LED matrix
+3. Provide audio input (microphone or line-in)
+4. Use the web UI to control visualizations
+5. Select different modes and adjust parameters in real-time
+
+## Performance Tips
+
+- This example requires significant processing power
+- Reduce matrix size if experiencing lag
+- Disable beat detection for lower CPU usage
+- Use simpler visualization modes on slower processors
+
+## Customization
+
+### Adding New Visualizations
+
+1. Add your mode name to the `visualMode` dropdown
+2. Create a new `drawYourMode()` function
+3. Add a case in the main switch statement
+4. Implement your visualization logic
+
+### Modifying Color Palettes
+
+Edit the `getCurrentPalette()` function to add custom palettes:
+```cpp
+case 7: return YourCustomPalette_p;
+```
+
+### Adjusting Matrix Size
+
+For different matrix sizes, modify:
+```cpp
+#define WIDTH your_width
+#define HEIGHT your_height
+```
+
+## Memory Usage
+
+This example uses approximately:
+- 30KB for LED buffer (100x100 RGB)
+- 2KB for FFT data
+- 1KB for audio buffers
+- Additional memory for effect buffers
+
+## Troubleshooting
+
+- **No visualization**: Check audio input and "Enable Audio" setting
+- **Choppy animation**: Reduce matrix size or disable some features
+- **No beat detection**: Increase beat sensitivity or check audio levels
+- **Dim display**: Increase brightness or check power supply
+- **Compilation error**: Ensure platform has sufficient memory
+
+## Credits
+
+This example demonstrates the audio processing capabilities of FastLED, including FFT analysis, beat detection, and various visualization techniques suitable for LED art installations, music visualizers, and interactive displays.
@@ -0,0 +1,562 @@
+/// @file    AudioReactive.ino
+/// @brief   Audio reactive visualization with multiple modes
+/// @example AudioReactive.ino
+
+#include <Arduino.h>
+#include <FastLED.h>
+
+
+
+#include "fl/ui.h"
+#include "fl/audio.h"
+#include "fl/fft.h"
+#include "fl/xymap.h"
+#include "fl/math.h"
+#include "fl/math_macros.h"
+
+#include "fl/compiler_control.h"
+
+// This is used by fastled because we have extremely strict compiler settings.
+// Stock Arduino/Platformio does not need these.
+FL_DISABLE_WARNING_PUSH
+FL_DISABLE_WARNING(float-conversion)
+FL_DISABLE_WARNING(sign-conversion)
+
+
+using namespace fl;
+
+// Display configuration
+// For WebAssembly, use a smaller display to avoid memory issues
+#ifdef __EMSCRIPTEN__
+#define WIDTH 32
+#define HEIGHT 32
+#else
+#define WIDTH 64
+#define HEIGHT 64
+#endif
+#define NUM_LEDS (WIDTH * HEIGHT)
+#define LED_PIN 3
+#define LED_TYPE WS2812B
+#define COLOR_ORDER GRB
+
+// Audio configuration
+#define SAMPLE_RATE 44100
+#define FFT_SIZE 512
+
+// UI Elements
+UITitle title("Audio Reactive Visualizations");
+UIDescription description("Real-time audio visualizations with beat detection and multiple modes");
+
+// Master controls
+UICheckbox enableAudio("Enable Audio", true);
+UIDropdown visualMode("Visualization Mode", 
+    {"Spectrum Bars", "Radial Spectrum", "Waveform", "VU Meter", "Matrix Rain", "Fire Effect", "Plasma Wave"});
+
+// Audio controls
+UISlider audioGain("Audio Gain", 1.0f, 0.1f, 5.0f, 0.1f);
+UISlider noiseFloor("Noise Floor", 0.1f, 0.0f, 1.0f, 0.01f);
+UICheckbox autoGain("Auto Gain", true);
+
+// Visual controls
+UISlider brightness("Brightness", 128, 0, 255, 1);
+UISlider fadeSpeed("Fade Speed", 20, 0, 255, 1);
+UIDropdown colorPalette("Color Palette", 
+    {"Rainbow", "Heat", "Ocean", "Forest", "Party", "Lava", "Cloud"});
+UICheckbox mirrorMode("Mirror Mode", false);
+
+// Beat detection
+UICheckbox beatDetect("Beat Detection", true);
+UISlider beatSensitivity("Beat Sensitivity", 1.5f, 0.5f, 3.0f, 0.1f);
+UICheckbox beatFlash("Beat Flash", true);
+
+// Audio input
+UIAudio audio("Audio Input");
+
+// Global variables
+CRGB leds[NUM_LEDS];
+XYMap xyMap(WIDTH, HEIGHT, false);
+SoundLevelMeter soundMeter(0.0, 0.0);
+
+// Audio processing variables - keep these smaller for WebAssembly
+static const int NUM_BANDS = 16;  // Reduced from 32
+float fftSmooth[NUM_BANDS] = {0};
+float beatHistory[20] = {0};  // Reduced from 43
+int beatHistoryIndex = 0;
+float beatAverage = 0;
+float beatVariance = 0;
+uint32_t lastBeatTime = 0;
+bool isBeat = false;
+float autoGainValue = 1.0f;
+float peakLevel = 0;
+
+// Visual effect variables
+uint8_t hue = 0;
+// Remove large static arrays for WebAssembly
+#ifndef __EMSCRIPTEN__
+float plasma[WIDTH][HEIGHT] = {{0}};
+uint8_t fireBuffer[WIDTH][HEIGHT] = {{0}};
+#endif
+
+// Get current color palette
+CRGBPalette16 getCurrentPalette() {
+    switch(colorPalette.as_int()) {
+        case 0: return CRGBPalette16(RainbowColors_p);
+        case 1: return CRGBPalette16(HeatColors_p);
+        case 2: return CRGBPalette16(OceanColors_p);
+        case 3: return CRGBPalette16(ForestColors_p);
+        case 4: return CRGBPalette16(PartyColors_p);
+        case 5: return CRGBPalette16(LavaColors_p);
+        case 6: return CRGBPalette16(CloudColors_p);
+        default: return CRGBPalette16(RainbowColors_p);
+    }
+}
+
+// Beat detection algorithm
+bool detectBeat(float energy) {
+    beatHistory[beatHistoryIndex] = energy;
+    beatHistoryIndex = (beatHistoryIndex + 1) % 20;
+    
+    // Calculate average
+    beatAverage = 0;
+    for (int i = 0; i < 20; i++) {
+        beatAverage += beatHistory[i];
+    }
+    beatAverage /= 20.0f;
+    
+    // Calculate variance
+    beatVariance = 0;
+    for (int i = 0; i < 20; i++) {
+        float diff = beatHistory[i] - beatAverage;
+        beatVariance += diff * diff;
+    }
+    beatVariance /= 20.0f;
+    
+    // Detect beat
+    float threshold = beatAverage + (beatSensitivity.value() * sqrt(beatVariance));
+    uint32_t currentTime = millis();
+    
+    if (energy > threshold && (currentTime - lastBeatTime) > 80) {
+        lastBeatTime = currentTime;
+        return true;
+    }
+    return false;
+}
+
+// Update auto gain
+void updateAutoGain(float level) {
+    if (!autoGain) {
+        autoGainValue = 1.0f;
+        return;
+    }
+    
+    static float targetLevel = 0.7f;
+    static float avgLevel = 0.0f;
+    
+    avgLevel = avgLevel * 0.95f + level * 0.05f;
+    
+    if (avgLevel > 0.01f) {
+        float gainAdjust = targetLevel / avgLevel;
+        gainAdjust = fl::clamp(gainAdjust, 0.5f, 2.0f);
+        autoGainValue = autoGainValue * 0.9f + gainAdjust * 0.1f;
+    }
+}
+
+// Clear display
+void clearDisplay() {
+    if (fadeSpeed.as_int() == 0) {
+        fill_solid(leds, NUM_LEDS, CRGB::Black);
+    } else {
+        fadeToBlackBy(leds, NUM_LEDS, fadeSpeed.as_int());
+    }
+}
+
+// Visualization: Spectrum Bars
+void drawSpectrumBars(FFTBins* fft, float /* peak */) {
+    clearDisplay();
+    CRGBPalette16 palette = getCurrentPalette();
+    
+    int barWidth = WIDTH / NUM_BANDS;
+    
+    for (size_t band = 0; band < NUM_BANDS && band < fft->bins_db.size(); band++) {
+        float magnitude = fft->bins_db[band];
+        
+        // Apply noise floor
+        magnitude = magnitude / 100.0f;  // Normalize from dB
+        magnitude = MAX(0.0f, magnitude - noiseFloor.value());
+        
+        // Smooth the FFT
+        fftSmooth[band] = fftSmooth[band] * 0.8f + magnitude * 0.2f;
+        magnitude = fftSmooth[band];
+        
+        // Apply gain
+        magnitude *= audioGain.value() * autoGainValue;
+        magnitude = fl::clamp(magnitude, 0.0f, 1.0f);
+        
+        int barHeight = magnitude * HEIGHT;
+        int xStart = band * barWidth;
+        
+        for (int x = 0; x < barWidth - 1; x++) {
+            for (int y = 0; y < barHeight; y++) {
+                uint8_t colorIndex = fl::map_range<float, uint8_t>(
+                    float(y) / HEIGHT, 0, 1, 0, 255
+                );
+                CRGB color = ColorFromPalette(palette, colorIndex + hue);
+                
+                int ledIndex = xyMap(xStart + x, y);
+                if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                    leds[ledIndex] = color;
+                }
+                
+                if (mirrorMode) {
+                    int mirrorIndex = xyMap(WIDTH - 1 - (xStart + x), y);
+                    if (mirrorIndex >= 0 && mirrorIndex < NUM_LEDS) {
+                        leds[mirrorIndex] = color;
+                    }
+                }
+            }
+        }
+    }
+}
+
+// Visualization: Radial Spectrum
+void drawRadialSpectrum(FFTBins* fft, float /* peak */) {
+    clearDisplay();
+    CRGBPalette16 palette = getCurrentPalette();
+    
+    int centerX = WIDTH / 2;
+    int centerY = HEIGHT / 2;
+    
+    for (size_t angle = 0; angle < 360; angle += 6) {  // Reduced resolution
+        size_t band = (angle / 6) % NUM_BANDS;
+        if (band >= fft->bins_db.size()) continue;
+        
+        float magnitude = fft->bins_db[band] / 100.0f;
+        magnitude = MAX(0.0f, magnitude - noiseFloor.value());
+        magnitude *= audioGain.value() * autoGainValue;
+        magnitude = fl::clamp(magnitude, 0.0f, 1.0f);
+        
+        int radius = magnitude * (MIN(WIDTH, HEIGHT) / 2);
+        
+        for (int r = 0; r < radius; r++) {
+            int x = centerX + (r * cosf(angle * PI / 180.0f));
+            int y = centerY + (r * sinf(angle * PI / 180.0f));
+            
+            if (x >= 0 && x < WIDTH && y >= 0 && y < HEIGHT) {
+                uint8_t colorIndex = fl::map_range<int, uint8_t>(r, 0, radius, 255, 0);
+                int ledIndex = xyMap(x, y);
+                if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                    leds[ledIndex] = ColorFromPalette(palette, colorIndex + hue);
+                }
+            }
+        }
+    }
+}
+
+// Visualization: Logarithmic Waveform (prevents saturation)
+void drawWaveform(const Slice<const int16_t>& pcm, float /* peak */) {
+    clearDisplay();
+    CRGBPalette16 palette = getCurrentPalette();
+    
+    int samplesPerPixel = pcm.size() / WIDTH;
+    int centerY = HEIGHT / 2;
+    
+    for (size_t x = 0; x < WIDTH; x++) {
+        size_t sampleIndex = x * samplesPerPixel;
+        if (sampleIndex >= pcm.size()) break;
+        
+        // Get the raw sample value
+        float sample = float(pcm[sampleIndex]) / 32768.0f;  // Normalize to -1.0 to 1.0
+        
+        // Apply logarithmic scaling to prevent saturation
+        float absSample = fabsf(sample);
+        float logAmplitude = 0.0f;
+        
+        if (absSample > 0.001f) {  // Avoid log(0)
+            // Logarithmic compression: log10(1 + gain * sample)
+            float scaledSample = absSample * audioGain.value() * autoGainValue;
+            logAmplitude = log10f(1.0f + scaledSample * 9.0f) / log10f(10.0f);  // Normalize to 0-1
+        }
+        
+        // Apply smooth sensitivity curve
+        logAmplitude = powf(logAmplitude, 0.7f);  // Gamma correction for better visual response
+        
+        // Calculate amplitude in pixels
+        int amplitude = int(logAmplitude * (HEIGHT / 2));
+        amplitude = fl::clamp(amplitude, 0, HEIGHT / 2);
+        
+        // Preserve the sign for proper waveform display
+        if (sample < 0) amplitude = -amplitude;
+        
+        // Color mapping based on amplitude intensity
+        uint8_t colorIndex = fl::map_range<int, uint8_t>(abs(amplitude), 0, HEIGHT/2, 40, 255);
+        CRGB color = ColorFromPalette(palette, colorIndex + hue);
+        
+        // Apply brightness scaling for low amplitudes
+        if (abs(amplitude) < HEIGHT / 4) {
+            color.fadeToBlackBy(128 - (abs(amplitude) * 512 / HEIGHT));
+        }
+        
+        // Draw vertical line from center
+        if (amplitude == 0) {
+            // Draw center point for zero amplitude
+            int ledIndex = xyMap(x, centerY);
+            if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                leds[ledIndex] = color.fadeToBlackBy(200);
+            }
+        } else {
+            // Draw line from center to amplitude
+            int startY = (amplitude > 0) ? centerY : centerY + amplitude;
+            int endY = (amplitude > 0) ? centerY + amplitude : centerY;
+            
+            for (int y = startY; y <= endY; y++) {
+                if (y >= 0 && y < HEIGHT) {
+                    int ledIndex = xyMap(x, y);
+                    if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                        // Fade edges for smoother appearance
+                        CRGB pixelColor = color;
+                        if (y == startY || y == endY) {
+                            pixelColor.fadeToBlackBy(100);
+                        }
+                        leds[ledIndex] = pixelColor;
+                    }
+                }
+            }
+        }
+    }
+}
+
+// Visualization: VU Meter
+void drawVUMeter(float rms, float peak) {
+    clearDisplay();
+    CRGBPalette16 palette = getCurrentPalette();
+    
+    // RMS level bar
+    int rmsWidth = rms * WIDTH * audioGain.value() * autoGainValue;
+    rmsWidth = MIN(rmsWidth, WIDTH);
+    
+    for (int x = 0; x < rmsWidth; x++) {
+        for (int y = HEIGHT/3; y < 2*HEIGHT/3; y++) {
+            uint8_t colorIndex = fl::map_range<int, uint8_t>(x, 0, WIDTH, 0, 255);
+            int ledIndex = xyMap(x, y);
+            if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                leds[ledIndex] = ColorFromPalette(palette, colorIndex);
+            }
+        }
+    }
+    
+    // Peak indicator
+    int peakX = peak * WIDTH * audioGain.value() * autoGainValue;
+    peakX = MIN(peakX, WIDTH - 1);
+    
+    for (int y = HEIGHT/4; y < 3*HEIGHT/4; y++) {
+        int ledIndex = xyMap(peakX, y);
+        if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+            leds[ledIndex] = CRGB::White;
+        }
+    }
+    
+    // Beat indicator
+    if (isBeat && beatFlash) {
+        for (int x = 0; x < WIDTH; x++) {
+            int ledIndex1 = xyMap(x, 0);
+            int ledIndex2 = xyMap(x, HEIGHT - 1);
+            if (ledIndex1 >= 0 && ledIndex1 < NUM_LEDS) leds[ledIndex1] = CRGB::White;
+            if (ledIndex2 >= 0 && ledIndex2 < NUM_LEDS) leds[ledIndex2] = CRGB::White;
+        }
+    }
+}
+
+// Visualization: Matrix Rain
+void drawMatrixRain(float peak) {
+    // Shift everything down
+    for (int x = 0; x < WIDTH; x++) {
+        for (int y = HEIGHT - 1; y > 0; y--) {
+            int currentIndex = xyMap(x, y);
+            int aboveIndex = xyMap(x, y - 1);
+            if (currentIndex >= 0 && currentIndex < NUM_LEDS && 
+                aboveIndex >= 0 && aboveIndex < NUM_LEDS) {
+                leds[currentIndex] = leds[aboveIndex];
+                leds[currentIndex].fadeToBlackBy(40);
+            }
+        }
+    }
+    
+    // Add new drops based on audio
+    int numDrops = peak * WIDTH * audioGain.value() * autoGainValue;
+    for (int i = 0; i < numDrops; i++) {
+        int x = random(WIDTH);
+        int ledIndex = xyMap(x, 0);
+        if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+            leds[ledIndex] = CHSV(96, 255, 255);  // Green
+        }
+    }
+}
+
+// Visualization: Fire Effect (simplified for WebAssembly)
+void drawFireEffect(float peak) {
+    // Simple fire effect without buffer
+    clearDisplay();
+    
+    // Add heat at bottom based on audio
+    int heat = 100 + (peak * 155 * audioGain.value() * autoGainValue);
+    heat = MIN(heat, 255);
+    
+    for (int x = 0; x < WIDTH; x++) {
+        for (int y = 0; y < HEIGHT; y++) {
+            // Simple gradient from bottom to top
+            int heatLevel = heat * (HEIGHT - y) / HEIGHT;
+            heatLevel = heatLevel * random(80, 120) / 100;  // Add randomness
+            heatLevel = MIN(heatLevel, 255);
+            
+            int ledIndex = xyMap(x, y);
+            if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                leds[ledIndex] = HeatColor(heatLevel);
+            }
+        }
+    }
+}
+
+// Visualization: Plasma Wave
+void drawPlasmaWave(float peak) {
+    static float time = 0;
+    time += 0.05f + (peak * 0.2f);
+    
+    CRGBPalette16 palette = getCurrentPalette();
+    
+    for (int x = 0; x < WIDTH; x++) {
+        for (int y = 0; y < HEIGHT; y++) {
+            float value = sinf(x * 0.1f + time) + 
+                         sinf(y * 0.1f - time) +
+                         sinf((x + y) * 0.1f + time) +
+                         sinf(sqrtf(x * x + y * y) * 0.1f - time);
+            
+            value = (value + 4) / 8;  // Normalize to 0-1
+            value *= audioGain.value() * autoGainValue;
+            
+            uint8_t colorIndex = value * 255;
+            int ledIndex = xyMap(x, y);
+            if (ledIndex >= 0 && ledIndex < NUM_LEDS) {
+                leds[ledIndex] = ColorFromPalette(palette, colorIndex + hue);
+            }
+        }
+    }
+}
+
+void setup() {
+    Serial.begin(115200);
+    delay(1000);
+    
+    Serial.println("Audio Reactive Visualizations");
+    Serial.println("Initializing...");
+    Serial.print("Display size: ");
+    Serial.print(WIDTH);
+    Serial.print("x");
+    Serial.println(HEIGHT);
+    
+    // Initialize LEDs
+    FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS);
+    FastLED.setBrightness(brightness.as_int());
+    FastLED.clear();
+    FastLED.show();
+    
+    // Set up UI callbacks
+    brightness.onChanged([](float value) {
+        FastLED.setBrightness(value);
+    });
+    
+    Serial.println("Setup complete!");
+}
+
+void loop() {
+    // Check if audio is enabled
+    if (!enableAudio) {
+        // Show a simple test pattern
+        fill_rainbow(leds, NUM_LEDS, hue++, 7);
+        FastLED.show();
+        delay(20);
+        return;
+    }
+    
+    // Process only one audio sample per frame to avoid accumulation
+    AudioSample sample = audio.next();
+    if (sample.isValid()) {
+        // Update sound meter
+        soundMeter.processBlock(sample.pcm());
+        
+        // Get audio levels
+        float rms = sample.rms() / 32768.0f;
+        
+        // Calculate peak
+        int32_t maxSample = 0;
+        for (size_t i = 0; i < sample.pcm().size(); i++) {
+            int32_t absSample = fabsf(sample.pcm()[i]);
+            if (absSample > maxSample) {
+                maxSample = absSample;
+            }
+        }
+        float peak = float(maxSample) / 32768.0f;
+        peakLevel = peakLevel * 0.9f + peak * 0.1f;  // Smooth peak
+        
+        // Update auto gain
+        updateAutoGain(rms);
+        
+        // Beat detection
+        if (beatDetect) {
+            isBeat = detectBeat(peak);
+        }
+        
+        // Get FFT data - create local FFTBins to avoid accumulation
+        FFTBins fftBins(NUM_BANDS);
+        sample.fft(&fftBins);
+        
+        // Update color animation
+        hue += 1;
+        
+        // Apply beat flash
+        if (isBeat && beatFlash) {
+            for (int i = 0; i < NUM_LEDS; i++) {
+                leds[i].fadeLightBy(-50);  // Make brighter
+            }
+        }
+        
+        // Draw selected visualization
+        switch (visualMode.as_int()) {
+            case 0:  // Spectrum Bars
+                drawSpectrumBars(&fftBins, peakLevel);
+                break;
+                
+            case 1:  // Radial Spectrum
+                drawRadialSpectrum(&fftBins, peakLevel);
+                break;
+                
+            case 2:  // Waveform
+                drawWaveform(sample.pcm(), peakLevel);
+                break;
+                
+            case 3:  // VU Meter
+                drawVUMeter(rms, peakLevel);
+                break;
+                
+            case 4:  // Matrix Rain
+                drawMatrixRain(peakLevel);
+                break;
+                
+            case 5:  // Fire Effect
+                drawFireEffect(peakLevel);
+                break;
+                
+            case 6:  // Plasma Wave
+                drawPlasmaWave(peakLevel);
+                break;
+        }
+    }
+    
+    FastLED.show();
+    
+    // Add a small delay to prevent tight loops in WebAssembly
+    #ifdef __EMSCRIPTEN__
+    delay(1);
+    #endif
+}
+
+FL_DISABLE_WARNING_POP
@@ -0,0 +1,157 @@
+# 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.
@@ -0,0 +1,64 @@
+#pragma once
+#include "fl/time_alpha.h"
+#include "fl/math_macros.h"
+
+/// Tracks a smoothed peak with attack, decay, and output-inertia time-constants.
+class MaxFadeTracker {
+public:
+    /// @param attackTimeSec  τ₁: how quickly to rise toward a new peak.
+    /// @param decayTimeSec   τ₂: how quickly to decay to 1/e of value.
+    /// @param outputTimeSec  τ₃: how quickly the returned value follows currentLevel_.
+    /// @param sampleRate     audio sample rate (e.g. 44100 or 48000).
+    MaxFadeTracker(float attackTimeSec,
+                   float decayTimeSec,
+                   float outputTimeSec,
+                   float sampleRate)
+      : attackRate_(1.0f / attackTimeSec)
+      , decayRate_(1.0f / decayTimeSec)
+      , outputRate_(1.0f / outputTimeSec)
+      , sampleRate_(sampleRate)
+      , currentLevel_(0.0f)
+      , smoothedOutput_(0.0f)
+    {}
+
+    void setAttackTime(float t){ attackRate_ = 1.0f/t; }
+    void setDecayTime (float t){  decayRate_ = 1.0f/t; }
+    void setOutputTime(float t){ outputRate_ = 1.0f/t; }
+
+    /// Process one 512-sample block; returns [0…1] with inertia.
+    float operator()(const int16_t* samples, size_t length) {
+        assert(length == 512);
+        // 1) block peak
+        float peak = 0.0f;
+        for (size_t i = 0; i < length; ++i) {
+            float v = ABS(samples[i]) * (1.0f/32768.0f);
+            peak = MAX(peak, v);
+        }
+
+        // 2) time delta
+        float dt = static_cast<float>(length) / sampleRate_;
+
+        // 3) update currentLevel_ with attack/decay
+        if (peak > currentLevel_) {
+            float riseFactor = 1.0f - fl::exp(-attackRate_ * dt);
+            currentLevel_ += (peak - currentLevel_) * riseFactor;
+        } else {
+            float decayFactor = fl::exp(-decayRate_ * dt);
+            currentLevel_ *= decayFactor;
+        }
+
+        // 4) output inertia: smooth smoothedOutput_ → currentLevel_
+        float outFactor = 1.0f - fl::exp(-outputRate_ * dt);
+        smoothedOutput_ += (currentLevel_ - smoothedOutput_) * outFactor;
+
+        return smoothedOutput_;
+    }
+
+private:
+    float attackRate_;    // = 1/τ₁
+    float decayRate_;     // = 1/τ₂
+    float outputRate_;    // = 1/τ₃
+    float sampleRate_;
+    float currentLevel_;  // instantaneous peak with attack/decay
+    float smoothedOutput_; // returned value with inertia
+};
@@ -0,0 +1,253 @@
+/// @file    Audio.ino
+/// @brief   Audio visualization example with XY mapping
+/// @example Audio.ino
+///
+/// This sketch is fully compatible with the FastLED web compiler. To use it do the following:
+/// 1. Install Fastled: `pip install fastled`
+/// 2. cd into this examples page.  
+/// 3. Run the FastLED web compiler at root: `fastled`
+/// 4. When the compiler is done a web page will open.
+
+/*
+This demo is best viewed using the FastLED compiler.
+
+Windows/MacOS binaries: https://github.com/FastLED/FastLED/releases
+
+Python
+
+Install: pip install fastled
+Run: fastled <this sketch directory>
+This will compile and preview the sketch in the browser, and enable
+all the UI elements you see below.
+*/
+
+#include <Arduino.h>
+#include <FastLED.h>
+
+#include "fl/audio.h"
+#include "fl/downscale.h"
+#include "fl/draw_visitor.h"
+#include "fl/fft.h"
+#include "fl/math.h"
+#include "fl/math_macros.h"
+#include "fl/raster.h"
+#include "fl/time_alpha.h"
+#include "fl/ui.h"
+#include "fl/xypath.h"
+#include "fl/unused.h"
+#include "fx/time.h"
+#include "fl/function.h"
+
+// Sketch.
+#include "fx_audio.h"
+
+#include "fl/memfill.h"
+using namespace fl;
+
+#define HEIGHT 128
+#define WIDTH 128
+#define NUM_LEDS ((WIDTH) * (HEIGHT))
+#define IS_SERPINTINE false
+#define TIME_ANIMATION 1000 // ms
+#define PIN_DATA 3
+
+UITitle title("Simple control of an xy path");
+UIDescription description("This is more of a test for new features.");
+UICheckbox enableVolumeVis("Enable volume visualization", false);
+UICheckbox enableRMS("Enable RMS visualization", false);
+UICheckbox enableFFT("Enable FFT visualization", true);
+UICheckbox freeze("Freeze frame", false);
+UIButton advanceFrame("Advance frame");
+UISlider decayTimeSeconds("Fade time Seconds", .1, 0, 4, .02);
+UISlider attackTimeSeconds("Attack time Seconds", .1, 0, 4, .02);
+UISlider outputTimeSec("outputTimeSec", .17, 0, 2, .01);
+
+UIAudio audio("Audio");
+UISlider fadeToBlack("Fade to black by", 5, 0, 20, 1);
+
+// Group related UI elements using UIGroup template multi-argument constructor
+UIGroup visualizationControls("Visualization", enableVolumeVis, enableRMS, enableFFT);
+UIGroup audioProcessingControls("Audio Processing", decayTimeSeconds, attackTimeSeconds, outputTimeSec);
+UIGroup generalControls("General Controls", freeze, advanceFrame, fadeToBlack);
+
+MaxFadeTracker audioFadeTracker(attackTimeSeconds.value(),
+                                decayTimeSeconds.value(), outputTimeSec.value(),
+                                44100);
+
+CRGB framebuffer[NUM_LEDS];
+XYMap frameBufferXY(WIDTH, HEIGHT, IS_SERPINTINE);
+
+CRGB leds[NUM_LEDS / 4]; // Downscaled buffer
+XYMap ledsXY(WIDTH / 2, HEIGHT / 2,
+             IS_SERPINTINE); // Framebuffer is regular rectangle LED matrix.
+
+FFTBins fftOut(WIDTH); // 2x width due to super sampling.
+
+// CRGB framebuffer[NUM_LEDS];
+// CRGB framebuffer[WIDTH_2X * HEIGHT_2X];  // 2x super sampling.
+// XYMap frameBufferXY(WIDTH, HEIGHT, IS_SERPINTINE);  // LED output, serpentine
+// as is common for LED matrices. XYMap xyMap_2X(WIDTH_2X, HEIGHT_2X, false); //
+// Framebuffer is regular rectangle LED matrix.
+
+int x = 0;
+int y = 0;
+bool triggered = false;
+
+SoundLevelMeter soundLevelMeter(.0, 0.0);
+
+float rms(Slice<const int16_t> data) {
+    double sumSq = 0.0;
+    const int N = data.size();
+    for (int i = 0; i < N; ++i) {
+        int32_t x32 = int32_t(data[i]);
+        sumSq += x32 * x32;
+    }
+    float rms = sqrt(float(sumSq) / N);
+    return rms;
+}
+
+void setup() {
+    Serial.begin(115200);
+    // auto screenmap = frameBufferXY.toScreenMap();
+    // screenmap.setDiameter(.2);
+    // FastLED.addLeds<NEOPIXEL, 2>(framebuffer,
+    // NUM_LEDS).setScreenMap(screenmap);
+    auto screenmap = ledsXY.toScreenMap();
+    screenmap.setDiameter(.2);
+
+    decayTimeSeconds.onChanged([](float value) {
+        audioFadeTracker.setDecayTime(value);
+        FASTLED_WARN("Fade time seconds: " << value);
+    });
+    attackTimeSeconds.onChanged([](float value) {
+        audioFadeTracker.setAttackTime(value);
+        FASTLED_WARN("Attack time seconds: " << value);
+    });
+    outputTimeSec.onChanged([](float value) {
+        audioFadeTracker.setOutputTime(value);
+        FASTLED_WARN("Output time seconds: " << value);
+    });
+    FastLED.addLeds<NEOPIXEL, PIN_DATA>(leds, ledsXY.getTotal())
+        .setScreenMap(screenmap);
+}
+
+void shiftUp() {
+    // fade each led by 1%
+    if (fadeToBlack.as_int()) {
+
+        for (int i = 0; i < NUM_LEDS; ++i) {
+            auto &c = framebuffer[i];
+            c.fadeToBlackBy(fadeToBlack.as_int());
+        }
+    }
+
+    for (int y = HEIGHT - 1; y > 0; --y) {
+        CRGB* row1 = &framebuffer[frameBufferXY(0, y)];
+        CRGB* row2 = &framebuffer[frameBufferXY(0, y - 1)];
+        memcpy(row1, row2, WIDTH * sizeof(CRGB));
+    }
+    CRGB* row = &framebuffer[frameBufferXY(0, 0)];
+    fl::memfill(row, 0, sizeof(CRGB) * WIDTH);
+}
+
+
+bool doFrame() {
+    if (!freeze) {
+        return true;
+    }
+    if (advanceFrame.isPressed()) {
+        return true;
+    }
+    return false;
+}
+
+void loop() {
+    if (triggered) {
+        FASTLED_WARN("Triggered");
+    }
+
+    // x = pointX.as_int();
+    y = HEIGHT / 2;
+
+    bool do_frame = doFrame();
+
+    while (AudioSample sample = audio.next()) {
+        if (!do_frame) {
+            continue;
+        }
+        float fade = audioFadeTracker(sample.pcm().data(), sample.pcm().size());
+        shiftUp();
+        // FASTLED_WARN("Audio sample size: " << sample.pcm().size());
+        soundLevelMeter.processBlock(sample.pcm());
+        // FASTLED_WARN("")
+        auto dbfs = soundLevelMeter.getDBFS();
+        FASTLED_UNUSED(dbfs);
+        // FASTLED_WARN("getDBFS: " << dbfs);
+        int32_t max = 0;
+        for (size_t i = 0; i < sample.pcm().size(); ++i) {
+            int32_t x = ABS(sample.pcm()[i]);
+            if (x > max) {
+                max = x;
+            }
+        }
+        float anim =
+            fl::map_range<float, float>(max, 0.0f, 32768.0f, 0.0f, 1.0f);
+        anim = fl::clamp(anim, 0.0f, 1.0f);
+
+        x = fl::map_range<float, float>(anim, 0.0f, 1.0f, 0.0f, WIDTH - 1);
+        // FASTLED_WARN("x: " << x);
+
+        // fft.run(sample.pcm(), &fftOut);
+        sample.fft(&fftOut);
+
+        // FASTLED_ASSERT(fftOut.bins_raw.size() == WIDTH_2X,
+        //                "FFT bins size mismatch");
+
+        if (enableFFT) {
+            auto max_x = fftOut.bins_raw.size() - 1;
+            FASTLED_UNUSED(max_x);
+            for (size_t i = 0; i < fftOut.bins_raw.size(); ++i) {
+                auto x = i;
+                auto v = fftOut.bins_db[i];
+                // Map audio intensity to a position in the heat palette (0-255)
+                v = fl::map_range<float, float>(v, 45, 70, 0, 1.f);
+                v = fl::clamp(v, 0.0f, 1.0f);
+                uint8_t heatIndex =
+                    fl::map_range<float, uint8_t>(v, 0, 1, 0, 255);
+
+                // FASTLED_WARN(v);
+
+                // Use FastLED's built-in HeatColors palette
+                auto c = ColorFromPalette(HeatColors_p, heatIndex);
+                c.fadeToBlackBy(255 - heatIndex);
+                framebuffer[frameBufferXY(x, 0)] = c;
+                // FASTLED_WARN("y: " << i << " b: " << b);
+            }
+        }
+
+        if (enableVolumeVis) {
+            framebuffer[frameBufferXY(x, HEIGHT / 2)] = CRGB(0, 255, 0);
+        }
+
+        if (enableRMS) {
+            float rms = sample.rms();
+            FASTLED_WARN("RMS: " << rms);
+            rms = fl::map_range<float, float>(rms, 0.0f, 32768.0f, 0.0f, 1.0f);
+            rms = fl::clamp(rms, 0.0f, 1.0f) * WIDTH;
+            framebuffer[frameBufferXY(rms, HEIGHT * 3 / 4)] = CRGB(0, 0, 255);
+        }
+        if (true) {
+            uint16_t fade_width = fade * (WIDTH - 1);
+            uint16_t h = HEIGHT / 4;
+            // yellow
+            int index = frameBufferXY(fade_width, h);
+            auto c = CRGB(255, 255, 0);
+            framebuffer[index] = c;
+        }
+    }
+
+    // now downscale the framebuffer to the led matrix
+    downscale(framebuffer, frameBufferXY, leds, ledsXY);
+
+    FastLED.show();
+}