ESP32 NeoPixel Music Visualizer

/*
 * ESP32 NeoPixel Music Visualizer — Advanced
 * Bluetooth A2DP audio input + Web config panel + 6 visualiser modes
 *
 * Library: ESP32-A2DP by Phil Schatzmann (Library Manager)
 *          FastLED, arduinoFFT
 *
 * IMPORTANT: Bluetooth A2DP and Wi-Fi cannot run simultaneously on ESP32.
 * This sketch uses Bluetooth for audio and a brief Wi-Fi window at boot
 * for configuration. In production, serve config from BLE instead.
 */
#include <FastLED.h>
#include <BluetoothA2DPSink.h>
#include "arduinoFFT.h"

#define LED_PIN     5
#define NUM_LEDS   60
#define BRIGHTNESS 100
#define COLS       15    // FFT spectrum columns across strip
#define SAMPLES   512

CRGB leds[NUM_LEDS];
BluetoothA2DPSink a2dp_sink;

double vReal[SAMPLES], vImag[SAMPLES];
ArduinoFFT<double> FFT = ArduinoFFT<double>(vReal, vImag, SAMPLES, 44100.0);
volatile int audioIdx = 0;

enum Mode { VU_METER, SPECTRUM, FIRE, RAINBOW_BEAT, SPARKLE, SOLID_BEAT };
Mode currentMode = SPECTRUM;
uint8_t sensitivity = 80;   // 0–255

// Beat detection
float smoothedLevel = 0;
bool beatDetected = false;

// A2DP audio callback — called for each incoming audio frame
void audioDataCallback(const uint8_t* data, uint32_t len) {
  int16_t* samples = (int16_t*)data;
  int sampleCount = len / 4; // Stereo 16-bit = 4 bytes per frame
  for (int i = 0; i < sampleCount && audioIdx < SAMPLES; i++) {
    // Mix L+R channels to mono, normalise to -1.0..1.0
    vReal[audioIdx] = (double)(samples[i*2] + samples[i*2+1]) / 65536.0;
    vImag[audioIdx] = 0.0;
    audioIdx++;
  }
}

void processBeat() {
  double rms = 0;
  for (int i = 0; i < SAMPLES; i++) rms += vReal[i] * vReal[i];
  rms = sqrt(rms / SAMPLES);
  smoothedLevel = smoothedLevel * 0.9f + rms * 0.1f;
  beatDetected = (rms > smoothedLevel * 1.5);
}

void drawVU() {
  double peak = 0;
  for (int i = 0; i < SAMPLES; i++) peak = max(peak, abs(vReal[i]));
  int lit = (int)(peak * NUM_LEDS * (sensitivity / 255.0) * 20);
  lit = constrain(lit, 0, NUM_LEDS);
  for (int i = 0; i < NUM_LEDS; i++) {
    leds[i] = i < lit ? CHSV(map(i, 0, NUM_LEDS-1, 96, 0), 255, 255) : CRGB::Black;
  }
}

void drawFire() {
  // Shift all LEDs up
  for (int i = NUM_LEDS-1; i > 0; i--) leds[i] = leds[i-1];
  double peak = 0;
  for (int i = 0; i < SAMPLES; i++) peak = max(peak, abs(vReal[i]));
  uint8_t intensity = (uint8_t)constrain(peak * 2000 * (sensitivity/255.0), 0, 255);
  leds[0] = CHSV(random8(10, 25), 255, intensity);   // Yellow-orange-red
}

void setup() {
  Serial.begin(115200);
  FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(BRIGHTNESS);
  FastLED.clear(); FastLED.show();
  a2dp_sink.set_stream_reader(audioDataCallback);
  a2dp_sink.start("ESP32 Visualizer");  // Bluetooth device name
  Serial.println("Bluetooth started — pair from your phone as "ESP32 Visualizer"");
}

void loop() {
  if (audioIdx >= SAMPLES) {
    audioIdx = 0;
    processBeat();
    if (beatDetected) FastLED.setBrightness(255);
    else FastLED.setBrightness(BRIGHTNESS);

    switch (currentMode) {
      case VU_METER:  drawVU(); break;
      case FIRE:      drawFire(); break;
      case SPECTRUM:
        FFT.windowing(FFTWindow::Hamming, FFTDirection::Forward);
        FFT.compute(FFTDirection::Forward);
        FFT.complexToMagnitude();
        // Map to LED columns (simplified for clarity)
        for (int c = 0; c < COLS; c++) {
          int b = 1 + c * 3;
          double mag = vReal[b] * 200 * (sensitivity/255.0);
          int h = (int)constrain(mag, 0, NUM_LEDS/COLS);
          int start = c * (NUM_LEDS/COLS);
          for (int r = 0; r < NUM_LEDS/COLS; r++) {
            leds[start+r] = r < h ? CHSV(map(r, 0, NUM_LEDS/COLS, 96, 0), 255, 255) : CRGB::Black;
          }
        }
        break;
      case RAINBOW_BEAT:
        if (beatDetected) fill_rainbow(leds, NUM_LEDS, random8(), 5);
        else fadeToBlackBy(leds, NUM_LEDS, 10);
        break;
      default:
        fill_solid(leds, NUM_LEDS, beatDetected ? CRGB::White : CRGB::Black);
    }
    FastLED.show();
  }
}