ESP32-AudioInI2S

A simple MEMS I2S microphone and audio processing library for ESP32.

Features

• Simple I2S sample reading and setup. Just choose the pins, sample size and sample rate.
• Robust audio processing library for analysis.
  • Simple FFT compute on your I2S samples.
  • Frequency bands in 2, 4, 8, 16, or 32 buckets.
  • Volume Unit Meter.
  • Set a noise floor to ignore values below it.
  • Normalize values into desired min/max ranges.
  • Auto level values for dynamic audio enviroments.
• Easy to follow examples
  • Basic - Reads I2S microphone data to be viewed in the Serial Plotter.
  • Frequencies - Reads I2S microphone data, processes them into frequency buckets to be viewed in the Serial Plotter.
  • FastLED - Reads I2S microphone data, processes them into frequency buckets and displays them on a WS2812B led strip.
  • OLED - coming soon.

Hardware

• ESP32, ESP32 S2, ESP32 C2, ESP32 C3
• INMP441 - MEMS Microphone

AudioInI2S - Functions

• #include <AudioInI2S.h>
• AudioInI2S(int bck_pin, int ws_pin, int data_pin, int channel_pin, i2s_channel_fmt_t channel_format) // pin setup
• void begin(int sample_size, int sample_rate = 44100, i2s_port_t i2s_port_number = I2S_NUM_0) - Starts the I2S DMA port.
• void read(int32_t _samples[]) - Stores the current I2S port buffer into samples.

AudioAnalysis - Functions

• #include <AudioAnalysis.h>
• AudioAnalysis()

FFT Functions

• void computeFFT(int32_t samples[], int sample_size, int sample_rate) - calculates FFT on sample data
• float *getReal() - gets the Real values after FFT calculation
• float *getImaginary() - gets the imaginary values after FFT calculation

Band Frequency Functions

• void setNoiseFloor(float noiseFloor) - threshold before sounds are registered

• void computeFrequencies(uint8_t band_size = BAND_SIZE) - converts FFT data into frequency bands

• void normalize(bool normalize = true, float min = 0, float max = 1) - normalize all values and constrain to min/max.

• void autoLevel(bool autoLevel, float min = 600, float max = 10000) - auto ballance normalized values to ambient noise levels.

• float *getBands() - gets the last bands calculated from processFrequencies()

• float *getPeaks() - gets the last peaks calculated from processFrequencies()

• float getBand(uint8_t index) - gets the value at bands index

• float getBandAvg() - average value across all bands

• int getBandMaxIndex() - index of the highest value band

• int getBandMinIndex() - index of the lowest value band

• float getPeak(uint8_t index) - gets the value at peaks index

• float getPeakAvg() - average value across all peaks

• int getPeakIndexMax() - index of the highest value peak

• int getPeakIndexMin() - index of the lowest value peak

Volume Unit Functions

• float getVolumeUnit() - gets the last volume unit calculated from processFrequencies()
• float getVolumeUnitPeak() - gets the last volume unit peak calculated from processFrequencies()
• float getVolumeUnitMax() - value of the highest value volume unit
• float getVolumeUnitMin() - value of the lowest value volume unit
• float getVolumeUnitPeakMax() - value of the highest value volume unit
• float getVolumeUnitPeakMin() - value of the lowest value volume unit

Example

Checkout the examples/Frequencies and examples/FastLED examples folder for audio analysis.

/* Basic.ino */
#include <AudioInI2S.h>

#define SAMPLE_SIZE 1024 // Buffer size of read samples
#define SAMPLE_RATE 44100 // Audio Sample Rate

// ESP32 S2 Mini 
#define BCK_PIN 4 // Clock pin from the mic.
#define WS_PIN 39 // WS pin from the mic.
#define DATA_PIN 5 // Data pin from the mic.
#define CHANNEL_SELECT_PIN 40 // Pin to select the channel output from the mic.

AudioInI2S mic(BCK_PIN, WS_PIN, DATA_PIN, CHANNEL_SELECT_PIN); // defaults to RIGHT channel.

int32_t samples[SAMPLE_SIZE]; // I2S sample data is stored here

void setup() {
    Serial.begin(115200);
    mic.begin(SAMPLE_SIZE, SAMPLE_RATE); // Starts the I2S DMA port.
}

void loop() {
    mic.read(samples); // Stores the current I2S port buffer into samples.

    // Send data to serial plotter
    for(int i = 0; i < SAMPLE_SIZE; i++) {
        Serial.println(samples[i]);
    }
}

Known Issues

The AudioAnalysis.h library is build on top of ArduinoFF2 V2 develop branch. You can find out more about it here: https://github.com/kosme/arduinoFFT/tree/develop

AudioAnalsis.h is not optimized and uses a lot of helper variables and floats. That said it is still very responsive at 1024 sample size and 44100 sample rate.

Recognition

This library's audio processing would not be possible without ArduinoFFT https://github.com/kosme/arduinoFFT

Licensing

MIT Open Source - Free to use anywhere.