获取系统音频

Question

我必须得到系统音频（混音器）。我试过这个：

Mixer.Info[] info = AudioSystem.getMixerInfo();
    try {
        for(Mixer.Info i : info) {
            Mixer mixer = AudioSystem.getMixer(i);
            Line.Info[] linesInfo = mixer.getTargetLineInfo();
            for(Line.Info lineInfo : linesInfo) {
                Line line = mixer.getLine(lineInfo);
                line.open();

                if(line.isControlSupported(FloatControl.Type.VOLUME)) {
                    FloatControl control = (FloatControl) line.getControl(FloatControl.Type.VOLUME);
                    System.out.println(control.getValue());
                }
            }
        }
    }
    catch(LineUnavailableException e) {
        e.printStackTrace();
    }

但它抛出LineUnavailableException（s）：

javax.sound.sampled.LineUnavailableException: line with format PCM_SIGNED 44100.0 Hz, 16 bit, stereo, 4 bytes/frame, little-endian not supported.
at com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(DirectAudioDevice.java:513)
at com.sun.media.sound.AbstractDataLine.open(AbstractDataLine.java:121)
at com.sun.media.sound.AbstractDataLine.open(AbstractDataLine.java:413)

如有必要，我可以使用外部库。