How to make opposite wave player

KTibow

Hi. I'm trying to make a program that plays the exact opposite of a sound wave. But before that, I need to learn how to properly access the microphone. Here's the sketch I'm trying:

import android.app.Activity;
import android.os.Bundle;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
short[] buffer = null;
AudioRecord audioRecord = null;
int bufferSize= 1024;
float volume = 0;
int buflen;
void setup() {
  orientation(PORTRAIT);
  int freq =44100;
  int chan = AudioFormat.CHANNEL_IN_MONO;
  int enc  = AudioFormat.ENCODING_PCM_16BIT;
  int src  = MediaRecorder.AudioSource.MIC;
  buflen = AudioRecord.getMinBufferSize(freq, chan, enc);
  bufferSize = buflen * 2;
  audioRecord = new AudioRecord(src, freq, chan, enc, buflen);
  println(audioRecord);
  audioRecord.startRecording();
  buffer = new short[bufferSize];
}
void draw() {
  background(200);
  audioRecord.read(buffer, 0, bufferSize);
  volume = abs(buffer[0]);
  text("" + volume, 100, 100);
  //draw a box if you blow the mic
  if (volume>300) {
    rect(10, 10, 20, 20);
  }
}
void stop() {
  audioRecord.stop();
  audioRecord.release();
  audioRecord = null;
}

But when I tried it, I got this exeption:

ION: Animation Thread
Process: processing.test.sketch_171211c, PID: 11072
java.lang.IllegalStateException: startRecording() called on an uninitialized AudioRecord.
    at android.media.AudioRecord.startRecording(AudioRecord.java:905)
    at processing.test.sketch_171211c.sketch_171211c.setup(sketch_171211c.java:47)
    at processing.core.PApplet.handleDraw(Unknown Source)
    at processing.core.PSurfaceNone.callDraw(Unknown Source)
    at processing.core.PSurfaceNone$AnimationThread.run(Unknown Source)

How should I fix it?

I am running a BLU phone.

akenaton

@KTibow===

• Are you ok with permissions?

• try to verify that your audiobuffer length is not <0 (use try catch for that)

• try to add some condition boolean before start recording (the audioRecord class has constant for that)

something like: if (audioRecord.getState() != AudioRecord.STATE_INITIALIZED) {"notReady"=true}

• try to create a thread for recording (though your message error is not about that)

KTibow

Okay, I'll look at my permissions. And I'll see what else there might be.