Android可以利用MediaRecorder和AudioRecord这两个工具来实现录音，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。
PS：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：
PS：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:id="@+id/btnRecord"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="开始边录边放"
/>
<Button
android:id="@+id/btnStop"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="停止"
/>
<Button
android:id="@+id/btnExit"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="退出"
>
<TextView
android:id="@+id/TextView01"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="程序音量调节"
/>
<SeekBar
android:id="@+id/skbVolume"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
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);
}
}
};
}
