Android 实现可视化动态音频柱状图

原文地址：http://www.jb51.net/article/32887.htm

先看一下效果图：

 

复制代码 代码如下:

public class FFTActivity extends Activity implements OnClickListener{
private Button button;
private ImageView imageView;
private int frequency = 8000;
private int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;
private int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;
private RealDoubleFFT transformer;
private int blockSize = 256;
private boolean started = false;
private Canvas canvas;
private Paint paint;
private Bitmap bitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fft);
button = (Button) findViewById(R.id.fft_button);
button.setOnClickListener(this);
imageView = (ImageView) findViewById(R.id.fft_imageView);
transformer = new RealDoubleFFT(blockSize);
bitmap = Bitmap.createBitmap(256, 100, Bitmap.Config.ARGB_8888);
canvas = new Canvas(bitmap);
paint = new Paint();
paint.setColor(Color.GREEN);
imageView.setImageBitmap(bitmap);
}
private class RecordAudio extends AsyncTask {
@Override
protected Void doInBackground(Void... params) {
int bufferSize = AudioRecord.getMinBufferSize(frequency,
channelConfiguration, audioEncoding);
AudioRecord audioRecord = new AudioRecord(
MediaRecorder.AudioSource.MIC, frequency,
channelConfiguration, audioEncoding, bufferSize);
short[] buffer = new short[blockSize];
double[] toTransform = new double[blockSize];
audioRecord.startRecording();
while (started) {
//将record的数据 读到buffer中，但是我认为叫做write可能会比较合适些。
int bufferResult = audioRecord.read(buffer, 0, blockSize);
for (int i = 0; i < bufferResult; i++) {
toTransform = (double) buffer / Short.MAX_VALUE;
}
transformer.ft(toTransform);
publishProgress(toTransform);
}
audioRecord.stop();
return null;
}
@Override
protected void onProgressUpdate(double[]... values) {
super.onProgressUpdate(values);
canvas.drawColor(Color.BLACK);
for (int i = 0; i < values[0].length; i++) {
int x=i;
int downy=(int)(100-(values[0])*10);
int upy=100;
canvas.drawLine(x, downy, x, upy, paint);
}
imageView.invalidate();
}
}
@Override
public void onClick(View v) {
started=true;
new RecordAudio().execute();
}
}

android音频可视化的原理是使用离散傅里叶变换，但是数学不好的同学不要担心，有开源的java离散傅里叶变换的代码！！直接到www.netlib.org/fftpack/jfftpack.tgz，直接将里面javasource目录拖动到（ca目录）src即可！！