I am new to processing, i am working on a project about changing the sound volume by pressing button. But how can i use the mp3 file, do i needa input it to the libraries?

I now using Ess for importing sound, but the processing is unble to load my mp3, so what can i do, the file is in the data folder of my sketch and here is the code

import krister.Ess.*;

Channel myChannel;

void setup() {
 size(256,200);

 // start up Ess
 Ess.start(this);

 // load "Intro.mp3" into a new Channel
 myChannel=new Channel();
 myChannel.loadSound("Intro.mp3");

 // start the sound looping forever
 myChannel.play(Ess.FOREVER);
}

void draw() {
}

// we are done, clean up Ess

public void stop() {
 Ess.stop();
 super.stop();
}

Is there something i did wrong?

what is the extra instrustion for importing mp3?

in this page, http://www.tree-axis.com/Ess/
i have downloaded all three jar files and put it in the library in the Ess library file, but i still can't import the mp3 file into it, is it there's still some problems there? or should i use sonia to do that instead of Ess?

I just got Krister's original code example working. Apart from putting your mp3 (check the file type!!) in the "data" folder, here are the three files you need to put in the "code" folder:

http://www.tree-axis.com/Ess/mp3_import.html

Though the volume of the sound is lower than needed