!7

import javax.sound.sampled.*;

static TargetDataLine currentLine;

p-substance {
  final L<Mixer> devices = inputAudioDevices();
  L<S> deviceNames = map(func(Mixer m) {
    audioDeviceName(m) + " [" + n(m.getTargetLineInfo(), "line") + "]"
  }, devices);
  ButtonGroup buttons = showUnselectedRadioButtons("Input Audio Devices", deviceNames);
  JFrame frame = minFrameWidth(300, packFrame(buttons));
  final JLabel lblLevel = jcenteredBoldLabel("Level: ");
  addToWindowAndPack(frame, lblLevel);
  awtEvery(lblLevel, 100, r {
    S text = "Level: ";
    if (currentLine != null) try {
      text += currentLine.getLevel();
    } catch e {
      text += str(e);
      printStackTrace(e);
    }
    lblLevel.setText(text);
  });
  onRadioButtonChange(buttons, voidfunc(int i) {
    if (i < 0) ret;
    Mixer m = devices.get(i);
    Line.Info[] lines = m.getTargetLineInfo();
    print("Device " + i + ": " + audioDeviceName(m));
    print("Have " + n(lines, "line"));
    currentLine = (TargetDataLine) m.getLine(first(lines));
  });
}

Began life as a copy of #1007014