How to reverse audio wave using processing - audio

Question

Is there a way to analyize the audio recorded by the application and reverse its wave? for example in Analog Audio the wave of sound is like a sinwave either 0,1,-1. I want to reverse that so that 1 will be -1 and the -1 be 1. How to do that using processing software?

Answer 1

Nikos is correct that the operation you are looking for is called Invert and not reverse. This achieved simply by multiplying every sample by -1.
The best way to do this is to use Minim, processing's audio library. You can extend the UGen class in order to make a new effects processor that flips every sample that goes through it. I've included an example below that works with a sine wave. You can change this around to be some other audio source and to draw it however you like.
import ddf.minim.*;
import ddf.minim.ugens.*;
Minim minim;
AudioOutput out;
void setup()
{
size(300, 200, P2D);
minim = new Minim(this);
out = minim.getLineOut();
Oscil osc;
Invert inv;
Constant cutoff;
// initialize the oscillator
// (a sawtooth wave has energy across the spectrum)
osc = new Oscil(500, 0.2, Waves.SINE);
inv = new Invert();
osc.patch(inv).patch(out);
}
void draw()
{
background( 0 );
}
public class Invert extends UGen{
public UGenInput audio;
Invert()
{
audio = new UGenInput(InputType.AUDIO);
}
#Override
protected void uGenerate (float[] channels)
{
if ( audio.isPatched() )
{
for (int i = 0; i < channels.length; i++){
// this is where we multiple each sample by -1
channels[i] = audio.getLastValues()[i] * -1;
}
}
}
}