如何从wav文件的字节数组中获取频率图？

Question

下面代码的目的是将wav文件转换为字节数组并绘制字节数组图。有没有人知道如何从wav文件中获取字节数组并将其转换为每次保存频率的数组？

buttonDecode.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                buttonStart.setEnabled(false);
                buttonDecode.setEnabled(false);
                buttonPlay.setEnabled(false);

                GraphView thegraph = (GraphView) findViewById(R.id.thegraph);
                series = new LineGraphSeries<DataPoint>();
                double x,y;
                x = 0;

                try {
                    ByteArrayOutputStream outt = new ByteArrayOutputStream();
                    BufferedInputStream in = new BufferedInputStream(new FileInputStream(wavfile));

                    int read;
                    byte[] buff = new byte[1024];
                    while ((read = in.read(buff)) > 0)
                    {
                        outt.write(buff, 0, read);
                    }
                    outt.flush();
                    byte[] audioBytes = outt.toByteArray();

                    //int[][] graphData = getUnscaledAmplitude(audioBytes, 1);

                    for(int i = 0; i < audioBytes.length;i++){


                        //System.out.println(audioBytes[i]);
                        byte curByte = audioBytes[i];
                        //int curByte = graphData[0][i];
                        y = (curByte);
                        series.appendData(new DataPoint(x,y), true, audioBytes.length);
                        x = x + 1;
                        //x = x + (1 / RECORDER_SAMPLERATE);
                    }
                    thegraph.addSeries(series);

                } catch (IOException e) {
                    e.printStackTrace();
                }

                buttonStart.setEnabled(true);
                buttonDecode.setEnabled(true);
                buttonPlay.setEnabled(true);

                //GRAPHING SECTION


            }
        });