Audio is certainly one of the most powerful tools at our disposal when it comes to making the players feel something from a video game. Audio can serve many different purposes in video games, such as giving feedback with sound effects, increasing immersion with ambient tracks, telling stories with recorded speech, or conveying all kinds of emotions through background music.

Video games have been making use of sound since their earliest days. For instance, the 1972 classic, Pong, used a beep sound effect to provide feedback whenever the ball collided with something, with different pitches used to distinguish between collisions with the walls, collisions with the paddles, or the ball leaving the game court.

Space Invaders, on the other hand, made a very clever use of its rudimentary background music by progressively increasing the speed of the song as the danger of the alien invasion drew closer, thus enhancing the feelings of tension within the player. Studies have shown that gamers that played the game without sound did not feel the same sense of urgency, and their heart rates did not rise like the ones that played the game with the sound turned on.

Since those days, there have been many advances in technology, which allowed audio in games to evolve considerably. Most games began using recorded audio instead of crude synthesized tones, and new techniques such as 3D audio now allow the players to feel like the sound is coming from all around them and interacting with the game environment.

Music has also played a very important role in video games. The popular Final Fantasy games owe a great portion of their emotional impact to the sweeping, cinematic soundtracks composed by Nobuo Uematsu. The most memorable scenes in the series would have not been the same without the music that accompanied them.

Many developers and composers have also looked into ways of making the music react to the game play. For example, starting with Monkey Island 2, LeChuck's Revenge, every graphic adventure game that LucasArts created uses a custom interactive music system called iMUSE, which among other features, allows seamless musical transitions between themes as the player moves from one room to another.

There are even games that incorporate audio concepts directly into their main gameplay mechanics, such as the songs that the player has to memorize and play in The Legend of Zelda: Ocarina of Time, and games that revolve entirely around sound, with the most popular examples being rhythm games, such as PaRappa the Rapper, Dance Dance Revolution, or Guitar Hero.

However, despite being such an important part of video games, many game development books skim through the subject of audio programming. Even the ones that dedicate a chapter to audio, often only teach you the very basics, such as loading and playing audio files, or use outdated audio engines instead of the ones used by the industry nowadays. Additionally, other game development topics, such as graphics, physics, or artificial intelligence tend to be more enticing to beginner level game developers and learning about audio becomes less of a priority.

The main goal of this book is to give you a crash course on audio programming for games by using a popular and well-established audio engine, and covering the subject from several different levels of abstraction. It is my hope that this approach will give you enough knowledge to implement most of the audio features that are normally required for a video game, and form a foundation so that you may pursue other topics that are more advanced.

#include <math.h>

float ChangeOctave(float frequency, float variation) {
  static float octave_ratio = 2.0f;
  return frequency * pow(octave_ratio, variation);
}
float ChangeSemitone(float frequency, float variation) {
  static float semitone_ratio = pow(2.0f, 1.0f / 12.0f);
  return frequency * pow(semitone_ratio, variation);
}

#include <SFML/Window.hpp>
#include "SimpleAudioManager.h"

int main() {
  sf::Window window(sf::VideoMode(320, 240), "AudioPlayback");
  sf::Clock clock;
  
  // Place your initialization logic here
  SimpleAudioManager audio;
  audio.Load("explosion.wav");
  
  // Start the game loop
  while (window.isOpen()) {
    // Only run approx 60 times per second
    float elapsed = clock.getElapsedTime().asSeconds();
    if (elapsed < 1.0f / 60.0f) continue;
    clock.restart();
    sf::Event event;
    while (window.pollEvent(event)) {
      // Handle window events
      if (event.type == sf::Event::Closed) 
        window.close();

      // Handle user input
      if (event.type == sf::Event::KeyPressed &&
          event.key.code == sf::Keyboard::Space)
        audio.Play("explosion.wav");
    }
    // Place your update and draw logic here
    audio.Update(elapsed);
  }
  // Place your shutdown logic here
  return 0;
}