Android音频可视化

相关链接：

Android 调用自带的录制音频程序
http://www.eoeandroid.com/thread-78949-1-1.html

 MediaRecoder实现音频录制并播放
http://www.eoeandroid.com/thread-237311-1-1.html

Android 音频的介绍
http://www.eoeandroid.com/thread-68377-1-1.html

--------------帖子正文----------------

先看一下效果图：

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<Void, double[], Void> {

 

                @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<i> = (double) buffer<i> / 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]<i>)*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！！