u/AdFlaky1032

```
#include <driver/i2s.h>


// ===================== I2S PORTS =====================
#define I2S_A I2S_NUM_0
#define I2S_B I2S_NUM_1


// ===================== ROOM A (I2S0) =====================
#define A_BCLK 16
#define A_LRCK 15
#define A_SDIN 17


#define A_DOUT 8


// ===================== ROOM B (I2S1) =====================
#define B_BCLK 5
#define B_LRCK 4
#define B_SDIN 6


#define B_DOUT 7


// ===================== BUFFERS =====================
int16_t bufA[128];
int16_t bufB[128];


// ===================== SETUP I2S A =====================
void setupI2S_A() {


  i2s_config_t configA = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_TX),
    .sample_rate = 16000,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
    .communication_format = I2S_COMM_FORMAT_I2S,
    .intr_alloc_flags = 0,
    .dma_buf_count = 4,
    .dma_buf_len = 64,
    .use_apll = false
  };


  i2s_pin_config_t pinsA = {
    .bck_io_num = A_BCLK,
    .ws_io_num = A_LRCK,
    .data_out_num = A_DOUT,
    .data_in_num = A_SDIN
  };


  i2s_driver_install(I2S_A, &configA, 0, NULL);
  i2s_set_pin(I2S_A, &pinsA);
}


// ===================== SETUP I2S B =====================
void setupI2S_B() {


  i2s_config_t configB = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_TX),
    .sample_rate = 16000,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
    .communication_format = I2S_COMM_FORMAT_I2S,
    .intr_alloc_flags = 0,
    .dma_buf_count = 4,
    .dma_buf_len = 64,
    .use_apll = false
  };


  i2s_pin_config_t pinsB = {
    .bck_io_num = B_BCLK,
    .ws_io_num = B_LRCK,
    .data_out_num = B_DOUT,
    .data_in_num = B_SDIN
  };


  i2s_driver_install(I2S_B, &configB, 0, NULL);
  i2s_set_pin(I2S_B, &pinsB);
}


// ===================== SETUP =====================
void setup() {
  Serial.begin(115200);


  setupI2S_A();
  setupI2S_B();


  Serial.println("Dual-room intercom started");
}


// ===================== LOOP =====================
void loop() {


  size_t bytesA, bytesB;


  // ---------- ROOM A ----------
  i2s_read(I2S_A, bufA, sizeof(bufA), &bytesA, portMAX_DELAY);


  for (int i = 0; i < bytesA / 2; i++) {
    bufA[i] *= 2.0; // gain
    bufA[i] = constrain(bufA[i], -32768, 32767);
  }


  i2s_write(I2S_A, bufA, bytesA, &bytesA, portMAX_DELAY);


  // ---------- ROOM B ----------
  i2s_read(I2S_B, bufB, sizeof(bufB), &bytesB, portMAX_DELAY);


  for (int i = 0; i < bytesB / 2; i++) {
    bufB[i] *= 2.0;
    bufB[i] = constrain(bufB[i], -32768, 32767);
  }


  i2s_write(I2S_B, bufB, bytesB, &bytesB, portMAX_DELAY);
}
```

When the gain is changed to less than or greater than 2.0, the output goes crazy. What is wrong with this code? What changes should I fix so I can change the gain with AGC.