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Submodule 18.3: Sound in p5.js

Site: ΕΛ/ΛΑΚ Moodle
Course: Study / Web Design and Web Development
Book: Submodule 18.3: Sound in p5.js
Printed by: Guest user
Date: Tuesday, 3 December 2024, 8:51 PM

Description

  • load and play sound
  • play and pause buttons
  • capture sound

Table of contents

load and play sound

p5.js has a build-in p5.js sound library which enables us to manipulate sound.

In order to load sound, we use the loadSound() function.  Similar to other media, we put this function inside the preload().

To actually play the sound we should use the play() function. 

Moreover, we can adjust the sound level by using the setVolume() function. This function takes values from 0.0 (minimum) to 1.0 (maximum).

Let's see an example of how the above should look like in the code.

Example 

Here is an example code where we load and play a sound:

function preload() {
 mySound = loadSound('sounds/Sg.mp3');
}

function setup() {
  // define the sound level
  mySound.setVolume(0.1);
  // play the sound
  mySound.play();
}

You can see the result of the above code here

Exercise

  1. Open your Visual Studio editor and the p5yourName folder.
  2. Open the file ex812.js in your editor and save it as ex1031.js
  3. Open the file ex812.html in your editor and save it as ex1031.html
  4. In the ex1031.html file, update the link to ex1031.js  from exersice812.js
  5. Go to the index.html file and create, under Module 10, a link to the ex1031.html  file with the title "load and play sound".

Modify the ex1031.jsfile and use as a base the above example to load a sound. The sound volume should increase as long as the mouse is pressed and when released, should return to the original volume. You can see here an example.

Answer:

function preload() {
 mySound = loadSound('sounds/Sg.mp3');
}

function setup() {
  // define the sound level
  mySound.setVolume(0.1);
  // play the sound
  mySound.play();
}
function mousePressed() {
  // increase sound level when mouse is pressed
  mySound.setVolume(0.5);
}
function mouseReleased() {
  // return to the original sound level
  mySound.setVolume(0.1);
}

Do a Git commit with the message "load and play sound".

play and pause buttons

In order to control whether our sound will play or pause we can create a button which will pause the sound if it is playing and make it play if it is not.

We have already see how we can make a sound play. In order to make it pause we use the pause() function.

However, how we can detect whether a sound is playing?

p5.js has the isPlaying() function. This function returns a boolean value which is true if the sound is playing and false if it is not.

Let's see how we can use it to play/pause our song.

Example 

Here is an example code where we use a button to play/pause a sound:

// create a variable for the button
let myBtn;
function preload() {
 mySound = loadSound('sounds/Sg.mp3');
}

function setup() {
  createCanvas(200,200);
  // create the button to control sound
  myBtn = createButton('play');
  // call the function playPause when the user presses the mouse
  myBtn.mousePressed(playPause);
}
function playPause(){
  //use the isPlaying to determine whether the sound is playing or not
  // if the sound is not playing
  if (!mySound.isPlaying()){
    // make it play
    mySound.play();
    // define the sound level
    mySound.setVolume(0.5);
  }
  // else pause it
  else {
    mySound.pause();
  }
}

You can see the result of the above code here. This example works best in mozilla firefox.

Exercise

  1. Open your Visual Studio editor and the p5yourName folder.
  2. Open the file ex812.js in your editor and save it as ex1032.js
  3. Open the file ex812.html in your editor and save it as ex1032.html
  4. In the ex1032.html file, update the link to ex1032.js  from exersice812.js
  5. Go to the index.html file and create, under Module 10, a link to the ex1032.html  file with the title "play and pause buttons".

Modify the ex1032.jsfile and use as a base the above example and load a sound which will start from the beginning each time the user presses the button. To do this you should use the stop() function for which you can learn more here. You can see here an example.

Answer:

// create a variable for the button
let myBtn;
function preload() {
 mySound = loadSound('sounds/Sg.mp3');
}

function setup() {
  createCanvas(200,200);
  // create the button to control sound
  myBtn = createButton('play');
  // call the function playPause when the user presses the mouse
  myBtn.mousePressed(playPause);
}
function playPause(){
  //use the isPlaying to determine whether the sound is playing or not
  // if the sound is not playing
  if (!mySound.isPlaying()){
    // make it play
    mySound.play();
    // define the sound level
    mySound.setVolume(0.5);
  }
  // else stop it
  else {
    mySound.stop();
  }
}

Do a Git commit with the message "play and pause buttons".

capture sound

p5.js gives us the ability to capture microphone sound from our computers.

In order to do that we use the constructor  new p5.AudioIn() function. 

To turn the microphone on we use the start() function and to turn it off we use the stop() function.

Moreover, we can get the volume levels of our microphone by using the getLevel() function. This functions returns values from 0.0 to 1.0.

Example 

Here is an example code where we capture microphone sound and draw an ellipse which will be changing size according to sound level:

// create variable to hold microphone inpute
let myMic;
function setup() {
  createCanvas(windowWidth, windowHeight);
  // capture microphone sound
  myMic = new p5.AudioIn();
  // turn on microphone
  myMic.start();
}
function draw() {
  background(123,23,45);
  // get the audio level
  let myMicLevel = myMic.getLevel();
  // create a sketch which will be changing according to audio level
  // we multiply the level by 1000 since the values it returns are very small
  ellipse(width / 2, height / 2, myMicLevel * 1000, myMicLevel * 1000);
}

You can see the result of the above code here

Exercise

  1. Open your Visual Studio editor and the p5yourName folder.
  2. Open the file ex812.js in your editor and save it as ex1033.js
  3. Open the file ex812.html in your editor and save it as ex1033.html
  4. In the ex1033.html file, update the link to ex1033.js  from exersice812.js
  5. Go to the index.html file and create, under Module 10, a link to the ex1033.html  file with the title "capture sound".

Modify the ex1033.jsfile and create an ellipse which will change color according to microphone volume. Moreover, if the volume is greater or equal to 100, keep its y position constant and change its x position according to volume. Else, change its y position. You can see here an example.

Answer:

/// create variable to hold microphone inpute
let myMic;
// create variables for RGB
let r,g,b;
function setup() {
  createCanvas(windowWidth, windowHeight);
  background(123,23,45);
  // capture microphone sound
  myMic = new p5.AudioIn();
  // turn on microphone
  myMic.start();

}
function draw() {

  // get the audio level
  let myMicLevel = myMic.getLevel();
  // change ellipse fill according to microphone volume
  r = myMicLevel * 2000;
  g = myMicLevel * 1000;
  b = myMicLevel * 800;
  fill (r,g,b,50);
  // create a sketch which will be changing according to audio level
  // if the volume is greater or equal to 100
  if (myMicLevel * 8000>=100){
    // change its x position
    ellipse((200+(myMicLevel * 8000)), 200, 200);
  }
  else {
    // else change its y position
    ellipse(200, (200+(myMicLevel * 8000)), 200); 
  }
}

Do a Git commit with the message "capture sound".