FFT and FormatConverterStream

[hdsjulian]

Full code below.

So my simple "take i2s input and detect main frequency" script sort of works fine, except that when i actually input stuff it gets me outputs like this

58.59 ovf => AS1 diff: 0.32
58.59 ovf => AS1 diff: 0.32
58.59 ovf => AS1 diff: 0.32

I was assuming this might have to do with the fact that AudioRealFFT can't handle 32bit samples?
So i decided to use FormatConverterStream (commented out in the code below) , but with that i don't get any output at all...
What might I be doing wrong?

#include <Arduino.h>
#include <AudioTools.h>
#include "AudioTools/AudioLibs/AudioRealFFT.h"

// I2S pins
#define I2S_BCK_PIN 14   // Bit Clock (BCK)
#define I2S_LRCK_PIN 15  // Left-Right Clock (LRCK)
#define I2S_DATA_PIN 12  // Data (DOUT)
#define CHANNELS 1
#define IN_SAMPLES_PER_SECOND 96000
#define IN_BITS_PER_SAMPLE 32

//Non Format Converter Stream Version
#define OUT_SAMPLES_PER_SECOND 96000
#define OUT_BITS_PER_SAMPLE 32\

//Format Converter Stream Version
//#define OUT_SAMPLES_PER_SECOND 44100
//#define OUT_BITS_PER_SAMPLE 16

I2SStream i2sStream;
AudioInfo from(96000, 1, 32);
AudioInfo to(44100, 1, 16);


AudioRealFFT afft;

//FormatConverterStream Version
// FormatConverterStream conv(afft);
//StreamCopy copier(conv, i2sStream);

//Non Format Converter Stream Version
StreamCopy copier(afft, i2sStream);
int bin_idx = 0;
// Buffer for audio samples
void fftResult(AudioFFTBase &fft){
  float diff;
  auto result = fft.result();
  if (result.magnitude>100){
      Serial.print(result.frequency);
      Serial.print(" ");
      Serial.print(result.magnitude);  
      Serial.print(" => ");
      Serial.print(result.frequencyAsNote(diff));
      Serial.print( " diff: ");
      Serial.println(diff);
  }
}


void setup() {
  Serial.begin(115200); // Initialize Serial for Serial Plotter
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Warning);

  // Configure I2S using AudioTools
  auto cfg = i2sStream.defaultConfig(RX_MODE);
  cfg.bits_per_sample = IN_BITS_PER_SAMPLE; // 16-bit samples
  cfg.channels = CHANNELS;         // Mono
  cfg.sample_rate = IN_SAMPLES_PER_SECOND;  // Sample rate
  cfg.is_master = false;    // Slave mode
  cfg.i2s_format = I2S_STD_FORMAT;
  cfg.use_apll = true;
  cfg.pin_bck = I2S_BCK_PIN;
  cfg.pin_ws = I2S_LRCK_PIN;
  cfg.pin_data_rx = I2S_DATA_PIN;

  auto tcfg = afft.defaultConfig();
  tcfg.length = 8192;
  tcfg.channels = CHANNELS;
  tcfg.sample_rate = OUT_SAMPLES_PER_SECOND;
  tcfg.bits_per_sample = OUT_BITS_PER_SAMPLE;
  tcfg.callback = &fftResult;
  afft.begin(tcfg);
  i2sStream.begin(cfg); // Start I2S

  //Format Converter Stream Version
  //conv.begin(from, to);

}



void loop() {
  copier.copy(); 
  }

[pschatzmann]

I am usually working with 16 bits, so this has never been tested with 32 bits.
I committed a correction to process the scaled float values

[hdsjulian]

Thanks! Works like a charm