Digitize Audio Input

[StevenSarns]

Hello All, Thanks in advance for any insights. I am very new to Processing. My project is to create an oscilloscope-like presentation of the signal on the MIC input of my desktop computer. The test waveform is a 20 Hz sawtooth wave generated by an external signal generator.

1 - the externally generated signal is being acquired correctly by the PC audio hardware as evidenced by a correct display using the example code in the minim getLineIn example.
2- my code generates the desired display when executed using the “test();” fake input generator function.
3 - when the “test()” call is commented out, I get an unintelligible image (see below)

I suspect that using a buffer size of 1 is the root of my problem (minim might normalize the data).

? - is there a simpler way to get a digitized sample of the MIC in?
? - am I missing something about the way getLineIn works?

import ddf.minim.*;
Minim minim;
AudioInput in;

void setup()
{
  size(1000, 200);
  minim = new Minim(this);
  in = minim.getLineIn(Minim.MONO,1);  // getLineIn(int type, int bufferSize, float sampleRate)
  background(0);
  stroke(255);
  frameRate(1000);                    // draw()/sec
}

int x;
int lastX=0;
float y;
float lastY=0;

void draw()
{
  x++;
  if(x>width) {
    x=0;
    lastX=0;
    background(0);
    stroke(255);
  }
  y = in.left.get(0);
  test();
  line(lastX,100+(lastY*100),x,100+(y*100));
  lastY=y;
  lastX=x;
}

void test() {
  float xx = x%50;
  y = xx/50 - .5;
}

[glv]

Please format your code when posting.
Try to cut and paste your current code into Processing and you will see why.

[glv]

When you “cut and paste” this from Processing (formatted code):

line(lastX,100+(lastY*100),x,100+(y*100));

This is what we see (unformatted code):
line(lastX,100+(lastY100),x,100+(y100));

Just highlight your code and click on the </> button in the editor.

[StevenSarns]

Thanks - I wondered how to do that.

import ddf.minim.*;
Minim minim;
AudioInput in;

void setup()
{
  size(1000, 200);
  minim = new Minim(this);
  in = minim.getLineIn(Minim.MONO,1);  // getLineIn(int type, int bufferSize, float sampleRate)
  background(0);
  stroke(255);
  frameRate(1000);                    // draw()/sec
}

int x;
int lastX=0;
float y;
float lastY=0;

void draw()
{
  x++;
  if(x>width) {
    x=0;
    lastX=0;
    background(0);
    stroke(255);
  }
  y = in.left.get(0);
//  test();
  line(lastX,100+(lastY*100),x,100+(y*100));
  lastY=y;
  lastX=x;
}

void test() {
  float xx = x%50;
  y = xx/50 - .5;
}

[glv]

Look at the “examples” that come with the minim library.

[StevenSarns]

Thanks, but…
The example you suggested fills a buffer, then plays the buffer. I am trying to get a single data point (buffer size of one) and plot that point. I am looking for a solution to the problem of acquiring a single data point.

[jeremydouglass]

Possibly relevant: an example of a minim oscilloscope.

Processing 2.x and 3.x Forum

[kll]

hi, @StevenSarns,
how is your project

• signal generator ( with 20Hz sawtooth sound output? )
• microphone PC sound card
• record to file? or looped to processing input
• scope like processing show

---

i am currently on a remake of a processing scope
using arduino USB connected analog inputs.
but think that sound frequencies are on the limit of that hardware.

as i lack the hardware ( calibrated signal generator ) even to see that my indicated
frequencies are nearly correct, i think after reading this post , that using a
sound / micro / arduino analog input /
might be a good idea and not need to buy much signal generation hardware,
just play a sound from any PC using ?audacity?

---

up to now i only have a signal from a other arduino ( DUE has analog output )
where i have no idea what frequency that might be
( can not calibrate one arduino with an other )

---

but i hope i get the mic input to a arduino working.
but yes, that is total different as your PC soundcard with micro / processing / minim lib / way.

[glv]

Simple online tone generator for audio range:
https://www.szynalski.com/tone-generator/