Java equivelant to AS3's sound.extract()?

Java Sound & OpenAL
#1

I’m trying to port some Actionscript code to Java, and I’m looking for a way to get an array of frequencies in a format where it’s 1 float per sample per channel and there’s 2 channels from an mp3 file.

Anyone have an example available on how to accomplish this?

#2

Do you really mean frequencies or just an array of samples?
Guessing you mean samples, check the documentation of JLayer (an mp3 decoder library) at http://www.javazoom.net/javalayer/documents.html
I never used JLayer myself, but I’m sure you can figure out how to get the decoded audio data from your mp3 using JLayer using the docs.

#3

hrmm I’ll look into it, but right now I’ve got this working:


import java.io.*;

import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;


public class JMFTest {

	public static void main(String[] args) throws Exception {
       FileInputStream in = new FileInputStream("test.mp3");
       AudioInputStream source = AudioSystem.getAudioInputStream(new BufferedInputStream(in, 1024));
       AudioInputStream pcm = AudioSystem.getAudioInputStream(AudioFormat.Encoding.PCM_SIGNED, source);
       File newFile = new File("test.wav");
       AudioSystem.write(pcm, AudioFileFormat.Type.WAVE, newFile);
       FileInputStream fis = new FileInputStream(newFile);
       ByteArrayOutputStream boas = new ByteArrayOutputStream(new Long(newFile.length()).intValue());
       byte[] buf = new byte[8 * 1024];
       for(int len=0; (len = fis.read(buf)) != -1;)
       {
    	   boas.write(buf,0,len);
       }
       byte[] ba = boas.toByteArray();
       for(int i = 44; i < ba.length; i+=2)
       {
    	   float value = ((ba[i] & 0xFF) | (ba[i + 1] << 8))/ 32768.0F;
    	   value /= 2.0;
    	   ba[i + 1] = (byte)((int)(value * 32768) >> 8);
    	   ba[i] = (byte)((int)(value * 32768) & 0xFF);
       }
       System.out.println(ba.length - 44);
       File newerFile = new File("test1.wav");
       FileOutputStream fos = new FileOutputStream(newerFile);
       fos.write(ba);
    }
}

right now it halves the volume of the sound file, but only seems to work in the format I want if the mp3 used is in the same format, so I’m looking for a simpler and more consistent way to do this, I’ll look into JLayer, and see if I can find what I’m looking for.

#4

(Fast) fourier transform will give you the spectrum. There’s plenty of Java FFT implementations around.