从android中的麦克风读取数据以在线处理它

Question

我在Android中从麦克风读取audiodata时遇到问题。我的应用程序必须根据我从麦克风上读取的声音音量来改变徽标图片的亮度。我使用AudioRecord类来获取audiodata。根据采样率和缓冲区大小，每第2 /第4 /第8次读取操作的延迟为100-200 ms。所以我的应用无法正确对音量变化作出反应。我试图减少缓冲区大小，并在其他线程中执行数据处理（使用AudioRecord.setPositionNotificationPeriod（）和回调），但那些没有多大意义 - 延迟只是变得更短。这是我的代码：

package com.mikesoft.Clown;

import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioRecord.OnRecordPositionUpdateListener;
import android.media.AudioRecord;
import android.media.MediaRecorder.AudioSource;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

import java.lang.Math;

public class TestActivity extends Activity implements OnClickListener, OnRecordPositionUpdateListener {

private static final String LOG_TAG = TestActivity.class.getSimpleName();

//arrays for selecting usable audioformat
private static int[] mSampleRates = new int[] {8000, 11025, 22050, 44100};
private static short[] audioFormat = new short[] {AudioFormat.ENCODING_PCM_8BIT, AudioFormat.ENCODING_PCM_16BIT};
private static short[] channelConfig = new short[] {AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.CHANNEL_CONFIGURATION_STEREO};

private short[][] buffers;
private int ix;

private AudioRecord recorder = null;
private int bufferSize = 0;
private AudioThread recordingThread = null;
private boolean isRecording = false;
/** The OpenGL View */
private LogoView glSurface;

//markers
private short[] buffer;
private long read_time;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.layout_test);
    findViewById(R.id.btnStart).setOnClickListener(this);
    findViewById(R.id.btnStop).setOnClickListener(this);
    mVolumeText = (TextView)findViewById(R.id.volume);

    setRecordMode();

    glSurface = (LogoView)findViewById(R.id.glSurface);
}

private void setRecordMode() {
    ((Button) findViewById(R.id.btnStop)).setClickable(isRecording);
    ((Button) findViewById(R.id.btnStart)).setClickable(!isRecording);
}

public void startRecording() {
    if (null == recorder) {
        recorder = findAudioRecord();

        recorder.setRecordPositionUpdateListener(this);

        recorder.startRecording();

        isRecording = true;

        recordingThread = new AudioThread();
    }
    Log.d(LOG_TAG, "Audio recording started");
}

//thread for executing audio recorder
private class AudioThread extends Thread {

    private AudioThread() {
        start();
    }

    @Override
    public void run() {
        android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_URGENT_AUDIO);
        recordAudio();
    }

}

private void recordAudio() {
        ix = 0;
    int read = 0;
    recorder.setPositionNotificationPeriod(bufferSize);
    while (isRecording) {
        //long t1 = System.currentTimeMillis();
        buffer = buffers[ix++ % buffers.length];
        read = recorder.read(buffer, 0, buffer.length);
        //time after reading
        //read_time = System.currentTimeMillis();
        //Log.d(LOG_TAG, "read bytes: " + read);
        //Log.d(LOG_TAG, "read_time=" + (read_time - t1));

        //int vol = 0;
        //for (int i=0;i<buffer.length;i++) 
        //  vol = Math.max(vol, Math.abs(buffer[i]));
        //float norm = (float)vol/(float)Short.MAX_VALUE;
        //glSurface.setLightness(norm);
    }
}

//initialize AudioRecord with suitable format
public AudioRecord findAudioRecord() {
    //for (int rate : mSampleRates) {
    int rate = 22050;
        for (short format : audioFormat) {
            for (short channel : channelConfig) {
                try {
                    Log.d(LOG_TAG, "Attempting rate " + rate + "Hz, bits: " + audioFormat + ", channel: "
                            + channelConfig);
                    bufferSize = AudioRecord.getMinBufferSize(rate, channel, format);

                    if (bufferSize != AudioRecord.ERROR_BAD_VALUE) {
                        // check if we can instantiate and have a success
                        AudioRecord recorder = new AudioRecord(AudioSource.MIC, rate, channel, format, bufferSize);
                            //bufferSize/=8;
                        if (recorder.getState() == AudioRecord.STATE_INITIALIZED) {
                            buffers = new short[256][bufferSize];
                            return recorder;
                        }
                    }
                } catch (Exception e) {
                    Log.e(LOG_TAG, rate + "Exception, keep trying.",e);
                }
            }
        }
        //}
        return null;
}

public void stopRecording() {
    if (null != recorder) {
        isRecording = false;

        recorder.stop();
        recorder.release();

        recorder = null;
        recordingThread = null;
    }
    Log.d(LOG_TAG, "Audio recording stopped");
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.btnStart:
        startRecording();
        setRecordMode();
        break;
    case R.id.btnStop:
        stopRecording();
        setRecordMode();
        break;
    default:
        break;
    }

}

@Override
public void onMarkerReached(AudioRecord arg0) {
    // TODO Auto-generated method stub
}

@Override
public void onPeriodicNotification(AudioRecord arg0) {
    float norm;
    short[] buf = buffers[ix % buffers.length];
    int vol = 0;
    for (int i = 0; i < buf.length; i++)
        vol = Math.max(vol, Math.abs(buf[i]));
    norm = (float) vol / (float) Short.MAX_VALUE;
    glSurface.setLightness(norm);
}

}

我尝试过使用Android 1.6-3.2的设备和模拟器，但到处都是一样的。我的Java问题有解决方案吗？或者我应该使用NDK方法？ 将不胜感激任何帮助。