Android之AudioRecord實現"助聽器"

原文鏈接（http://blog.csdn.net/hellogv/article/details/6026455）

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裏面添加這句：

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

main.xml的源碼如下：

<?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="開始邊錄邊放"></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="程序音量調節" 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的源碼如下：

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;//調節音量
    boolean isRecording = false;//是否錄放的標記
    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("助聽器");
        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);//音量調節的極限
        skbVolume.setProgress(70);//設置seekbar的位置值
        audioTrack.setStereoVolume(0.7f, 0.7f);//設置當前音量大小
        skbVolume.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
                float vol=(float)(seekBar.getProgress())/(float)(seekBar.getMax());
                audioTrack.setStereoVolume(vol, vol);//設置音量
            }

            @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();// 開一條線程邊錄邊放
            } 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();//開始錄製
                audioTrack.play();//開始播放

                while (isRecording) {
                    //從MIC保存數據到緩衝區
                    int bufferReadResult = audioRecord.read(buffer, 0,
                            recBufSize);

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