Android提高21篇之十：AudioRecord實現助聽器

       Android可以通過MediaRecorder和AudioRecord這兩個工具來實現錄音，MediaRecorder直接把麥克風的數據存到文件，並且能夠直接進行編碼(如AMR,MP3等)，而AudioRecord則是讀取麥克風的音頻流。本文使用AudioRecord讀取音頻流，使用AudioTrack播放音頻流，通過“邊讀邊播放”以及增大音量的方式來實現一個簡單的助聽器程序。

       PS：由於目前的Android模擬器還不支持AudioRecord，因此本程序需要編譯之後放到真機運行。

       先貼出本文程序運行截圖：

       PS：程序音量調節只是程序內部調節音量而已，要調到最大音量還需要手動設置系統音量。

       使用AudioRecord必須要申請許可，在AndroidManifest.xml裡面添加這句：

       main.xml的源碼如下：

1. <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"   
2.         android:orientation="vertical" android:layout_width="fill_parent"  
3.         android:layout_height="fill_parent">  
4.   
5.         <button android:layout_height="wrap_content" android:id="@+id/btnRecord"   
6.                 android:layout_width="fill_parent" android:text="開始邊錄邊放">  
7.         <button android:layout_height="wrap_content"   
8.                 android:layout_width="fill_parent" android:text="停止" android:id="@+id/btnStop">  
9.         <button android:layout_height="wrap_content" android:id="@+id/btnExit"   
10.                 android:layout_width="fill_parent" android:text="退出">  
11.         <textview android:id="@+id/TextView01" android:layout_height="wrap_content"   
12.                 android:text="程序音量調節" android:layout_width="fill_parent">  
13.         <seekbar android:layout_height="wrap_content" android:id="@+id/skbVolume"   
14.                 android:layout_width="fill_parent">  

       testRecord.java的源碼如下：

1. package com.testRecord;  
2.   
3. import android.app.Activity;  
4. import android.media.AudioFormat;  
5. import android.media.AudioManager;  
6. import android.media.AudioRecord;  
7. import android.media.AudioTrack;  
8. import android.media.MediaRecorder;  
9. import android.os.Bundle;  
10. import android.view.View;  
11. import android.widget.Button;  
12. import android.widget.SeekBar;  
13. import android.widget.Toast;  
14.   
15. public class testRecord extends Activity {  
16.         /** Called when the activity is first created. */  
17.         Button btnRecord, btnStop, btnExit;  
18.         SeekBar skbVolume;//調節音量  
19.         boolean isRecording = false;//是否錄放的標記  
20.         static final int frequency = 44100;  
21.         static final int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;  
22.         static final int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;  
23.         int recBufSize,playBufSize;  
24.         AudioRecord audioRecord;  
25.         AudioTrack audioTrack;  
26.   
27.         @Override  
28.         public void onCreate(Bundle savedInstanceState) {  
29.                 super.onCreate(savedInstanceState);  
30.                 setContentView(R.layout.main);  
31.                 setTitle("助聽器");  
32.                 recBufSize = AudioRecord.getMinBufferSize(frequency,  
33.                                 channelConfiguration, audioEncoding);  
34.   
35.                 playBufSize=AudioTrack.getMinBufferSize(frequency,  
36.                                 channelConfiguration, audioEncoding);  
37.                 // -----------------------------------------  
38.                 audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency,  
39.                                 channelConfiguration, audioEncoding, recBufSize);  
40.   
41.                 audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, frequency,  
42.                                 channelConfiguration, audioEncoding,  
43.                                 playBufSize, AudioTrack.MODE_STREAM);  
44.                 //------------------------------------------  
45.                 btnRecord = (Button) this.findViewById(R.id.btnRecord);  
46.                 btnRecord.setOnClickListener(new ClickEvent());  
47.                 btnStop = (Button) this.findViewById(R.id.btnStop);  
48.                 btnStop.setOnClickListener(new ClickEvent());  
49.                 btnExit = (Button) this.findViewById(R.id.btnExit);  
50.                 btnExit.setOnClickListener(new ClickEvent());  
51.                 skbVolume=(SeekBar)this.findViewById(R.id.skbVolume);  
52.                 skbVolume.setMax(100);//音量調節的極限  
53.                 skbVolume.setProgress(70);//設置seekbar的位置值  
54.                 audioTrack.setStereoVolume(0.7f, 0.7f);//設置當前音量大小  
55.                 skbVolume.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {  
56.                           
57.                         @Override  
58.                         public void onStopTrackingTouch(SeekBar seekBar) {  
59.                                 float vol=(float)(seekBar.getProgress())/(float)(seekBar.getMax());  
60.                                 audioTrack.setStereoVolume(vol, vol);//設置音量  
61.                         }  
62.                           
63.                         @Override  
64.                         public void onStartTrackingTouch(SeekBar seekBar) {  
65.                                 // TODO Auto-generated method stub  
66.                         }  
67.                           
68.                         @Override  
69.                         public void onProgressChanged(SeekBar seekBar, int progress,  
70.                                         boolean fromUser) {  
71.                                 // TODO Auto-generated method stub  
72.                         }  
73.                 });  
74.         }  
75.   
76.         @Override  
77.         protected void onDestroy() {  
78.                 super.onDestroy();  
79.                 android.os.Process.killProcess(android.os.Process.myPid());  
80.         }  
81.   
82.         class ClickEvent implements View.OnClickListener {  
83.   
84.                 @Override  
85.                 public void onClick(View v) {  
86.                         if (v == btnRecord) {  
87.                                 isRecording = true;  
88.                                 new RecordPlayThread().start();// 開一條線程邊錄邊放  
89.                         } else if (v == btnStop) {  
90.                                 isRecording = false;  
91.                         } else if (v == btnExit) {  
92.                                 isRecording = false;  
93.                                 testRecord.this.finish();  
94.                         }  
95.                 }  
96.         }  
97.   
98.         class RecordPlayThread extends Thread {  
99.                 public void run() {  
100.                         try {  
101.                                 byte[] buffer = new byte[recBufSize];  
102.                                 audioRecord.startRecording();//開始錄制  
103.                                 audioTrack.play();//開始播放  
104.                                   
105.                                 while (isRecording) {  
106.                                         //從MIC保存數據到緩沖區  
107.                                         int bufferReadResult = audioRecord.read(buffer, 0,  
108.                                                         recBufSize);  
109.   
110.                                         byte[] tmpBuf = new byte[bufferReadResult];  
111.                                         System.arraycopy(buffer, 0, tmpBuf, 0, bufferReadResult);  
112.                                         //寫入數據即播放  
113.                                         audioTrack.write(tmpBuf, 0, tmpBuf.length);  
114.                                 }  
115.                                 audioTrack.stop();  
116.                                 audioRecord.stop();  
117.                         } catch (Throwable t) {  
118.                                 Toast.makeText(testRecord.this, t.getMessage(), 1000);  
119.                         }  
120.                 }  
121.         };  
122. }