I've followed the directions from this answer, to try and play music without delay. This is my code so far:

#include "pitches.h"

int melody[] = {
  NOTE_C4, NOTE_G3, NOTE_G3, NOTE_A3, NOTE_G3, 0, NOTE_B3, NOTE_C4
};

int noteDurations[] = {
  4, 8, 8, 4, 4, 4, 4, 4
};

const int tonePin = 4;
unsigned long previousMillis = 0;
int counter = 0;
int numberOfNotes = sizeof(melody)/sizeof(int);
boolean outputTone = false;

void setup() {
  pinMode(tonePin, OUTPUT); 
  //Serial.begin(9600);
}

void loop() {
  unsigned long currentMillis = millis();
  unsigned long noteDuration = 1000 / noteDurations[counter];
  unsigned long pauseBetweenNotes = noteDuration * 1.30;
  
  
  if (counter < numberOfNotes) {
    if (outputTone && ((currentMillis - previousMillis) >= noteDuration)) {
        previousMillis = currentMillis;
        noTone(tonePin);
        outputTone = false;
        counter++;
    }
    else {
        if ((currentMillis - previousMillis) >= pauseBetweenNotes) {
        previousMillis = currentMillis;
        Serial.println(melody[counter]);
        
        if (melody[counter] == 0) {
          noTone(tonePin);
        } else {
          tone(tonePin, melody[counter]);
        }
        
        outputTone = true;
      }
    }
  }
}

pitches.h can be found here.

So with this code, the music plays, but slower. The pauses between notes seem longer, and I can't figure out why.

Also, I'm not sure where should I increment my notes counter.

I've followed the directions from this answer, to try and play music without delay. This is my code so far:

#include "pitches.h"

int melody[] = {
  NOTE_C4, NOTE_G3, NOTE_G3, NOTE_A3, NOTE_G3, 0, NOTE_B3, NOTE_C4
};

int noteDurations[] = {
  4, 8, 8, 4, 4, 4, 4, 4
};

const int tonePin = 4;
unsigned long previousMillis = 0;
int counter = 0;
int numberOfNotes = sizeof(melody)/sizeof(int);
boolean outputTone = false;

void setup() {
  pinMode(tonePin, OUTPUT); 
  //Serial.begin(9600);
}

void loop() {
  unsigned long currentMillis = millis();
  unsigned long noteDuration = 1000 / noteDurations[counter];
  unsigned long pauseBetweenNotes = noteDuration * 1.30;
  
  
  if (counter < numberOfNotes) {
    if (outputTone && ((currentMillis - previousMillis) >= noteDuration)) {
        previousMillis = currentMillis;
        noTone(tonePin);
        outputTone = false;
        counter++;
    }
    else {
        if ((currentMillis - previousMillis) >= pauseBetweenNotes) {
        previousMillis = currentMillis;
        Serial.println(melody[counter]);
        
        if (melody[counter] == 0) {
          noTone(tonePin);
        } else {
          tone(tonePin, melody[counter]);
        }
        
        outputTone = true;
      }
    }
  }
}

pitches.h can be found here.

So with this code, the music plays, but slower. The pauses between notes seem longer, and I can't figure out why.

Also, I'm not sure where should I increment my notes counter.