Android提高之AudioRecord实现助听器的方法

通常来说，在进行Android项目开发的时候可以通过MediaRecorder和AudioRecord这两个工具来实现录音的功能，MediaRecorder直接把麦克风的数据存到文件，并且能够直接进行编码(如AMR,MP3等)，而AudioRecord则是读取麦克风的音频流。本文使用AudioRecord读取音频流，使用AudioTrack播放音频流，通过“边读边播放”以及增大音量的方式来实现一个简单的助听器程序。

此处需要注意：由于目前的Android模拟器还不支持AudioRecord，因此本程序需要编译之后放到真机运行。

先贴出本文程序运行截图：

另外还要注意：在本程序音量调节只是程序内部调节音量而已，要调到最大音量还需要手动设置系统音量。

使用AudioRecord必须要申请许可，在AndroidManifest.xml里面添加这句：

<uses-permission android:name="android.permission.RECORD_AUDIO"></uses-permission>

main.xml的源码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">

 <Button android:layout_height="wrap_content" android:id="@+id/btnRecord"
 android:layout_width="fill_parent" android:text="开始边录边放"></Button>
 <Button android:layout_height="wrap_content"
 android:layout_width="fill_parent" android:text="停止" android:id="@+id/btnStop"></Button>
 <Button android:layout_height="wrap_content" android:id="@+id/btnExit"
 android:layout_width="fill_parent" android:text="退出"></Button>
 <TextView android:id="@+id/TextView01" android:layout_height="wrap_content"
 android:text="程序音量调节" android:layout_width="fill_parent"></TextView>
 <SeekBar android:layout_height="wrap_content" android:id="@+id/skbVolume"
 android:layout_width="fill_parent"></SeekBar>

</LinearLayout>

testRecord.java的源码如下：

package com.testRecord;
import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.Toast;
public class testRecord extends Activity {
 /** Called when the activity is first created. */
 Button btnRecord, btnStop, btnExit;
 SeekBar skbVolume;//调节音量
 boolean isRecording = false;//是否录放的标记
 static final int frequency = 44100;
 static final int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;
 static final int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;
 int recBufSize,playBufSize;
 AudioRecord audioRecord;
 AudioTrack audioTrack;
 @Override
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
 setTitle("助听器");
 recBufSize = AudioRecord.getMinBufferSize(frequency,
  channelConfiguration, audioEncoding);

 playBufSize=AudioTrack.getMinBufferSize(frequency,
  channelConfiguration, audioEncoding);
 // -----------------------------------------
 audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency,
  channelConfiguration, audioEncoding, recBufSize);

 audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, frequency,
  channelConfiguration, audioEncoding,
  playBufSize, AudioTrack.MODE_STREAM);
 //------------------------------------------
 btnRecord = (Button) this.findViewById(R.id.btnRecord);
 btnRecord.setOnClickListener(new ClickEvent());
 btnStop = (Button) this.findViewById(R.id.btnStop);
 btnStop.setOnClickListener(new ClickEvent());
 btnExit = (Button) this.findViewById(R.id.btnExit);
 btnExit.setOnClickListener(new ClickEvent());
 skbVolume=(SeekBar)this.findViewById(R.id.skbVolume);
 skbVolume.setMax(100);//音量调节的极限
 skbVolume.setProgress(70);//设置seekbar的位置值
 audioTrack.setStereoVolume(0.7f, 0.7f);//设置当前音量大小
 skbVolume.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
  @Override
  public void onStopTrackingTouch(SeekBar seekBar) {
  float vol=(float)(seekBar.getProgress())/(float)(seekBar.getMax());
  audioTrack.setStereoVolume(vol, vol);//设置音量
  }

  @Override
  public void onStartTrackingTouch(SeekBar seekBar) {
  // TODO Auto-generated method stub
  }

  @Override
  public void onProgressChanged(SeekBar seekBar, int progress,
   boolean fromUser) {
  // TODO Auto-generated method stub
  }
 });
 }
 @Override
 protected void onDestroy() {
 super.onDestroy();
 android.os.Process.killProcess(android.os.Process.myPid());
 }
 class ClickEvent implements View.OnClickListener {

 @Override
 public void onClick(View v) {
  if (v == btnRecord) {
  isRecording = true;
  new RecordPlayThread().start();// 开一条线程边录边放
  } else if (v == btnStop) {
  isRecording = false;
  } else if (v == btnExit) {
  isRecording = false;
  testRecord.this.finish();
  }
 }
 }
 class RecordPlayThread extends Thread {
 public void run() {
  try {
  byte[] buffer = new byte[recBufSize];
  audioRecord.startRecording();//开始录制
  audioTrack.play();//开始播放
  while (isRecording) {
   //从MIC保存数据到缓冲区
   int bufferReadResult = audioRecord.read(buffer, 0,
    recBufSize);

   byte[] tmpBuf = new byte[bufferReadResult];
   System.arraycopy(buffer, 0, tmpBuf, 0, bufferReadResult);
   //写入数据即播放
   audioTrack.write(tmpBuf, 0, tmpBuf.length);
  }
  audioTrack.stop();
  audioRecord.stop();
  } catch (Throwable t) {
  Toast.makeText(testRecord.this, t.getMessage(), 1000);
  }
 }
 };
}

希望本文所述实例对大家的Android项目开发有一定的借鉴价值。