Audio input capture in Java - byte array

Question

I'm trying to get double/intger amplitude values for audio input:

AudioFormat format = new AudioFormat(8000.0f, 8, 1, true, true);

    TargetDataLine line = null;
    DataLine.Info info = new DataLine.Info(TargetDataLine.class,
            format); 
    if (!AudioSystem.isLineSupported(info)) {

    }

    try {
        line = (TargetDataLine) AudioSystem.getLine(info);
        line.open(format);
    } catch (LineUnavailableException ex) {
        // Handle the error ...
    }

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    int numBytesRead;
    byte[] data = new byte[line.getBufferSize() / 5];


    line.start();

    while (true) {

        numBytesRead = line.read(data, 0, data.length);
        // Save this chunk of data.
        out.write(data, 0, numBytesRead);
        for(int i=0; i<numBytesRead; i+=1) {
            System.out.println(Byte.toString(data[i]));

        }
        System.out.println();
    }

I can't understand why byte array contains only values 0, -1 or 1. How to get double or integer values of amplitude.

Answer 1

The solution is to set microphone device more sensitive. :)