Android音频采集.doc

Android的多媒体框架包括了对各种通用音频格式进行采集和编码的支持，因此你能够容易的把音频集成到你的应用程序中。如果设备硬件支持，你还能够使用MediaRecorder API来记录音频。本文向你展示如何编写从设备的麦克中采集音频、保存并播放它的应用程序。注意：Android模拟器没有采集音频的能力，但是实际的设备可能提供这种能力。执行音频采集从设备上采集音频比音视频播放要复杂一些，但依然相当简单：1. 创建一个新的android.media.MediaRecorder类的实例；2. 使用MediaRecorder.setAudioSource()方法设置音频源。你可能还想使用MediaRecorder.AudioSource.MIC;3. 使用MediaRecorder.setOutputFormat()方法设置输出文件格式；4. 使用MediaRecorder.setOutputFile()方法设置输出文件名；5. 使用MediaRecorder.setAudioEncoder()方法设置音频编码；6. 调用MediaRecorder实例上的MediaRecorder.prepare()方法；7. 调用MediaRecorder.start()方法启动音频采集；8. 调用MediaRecorder.stop()方法终止音频采集；9. 使用完MediaRecorder实例后，调用它的MediaRecorder.release()方法。要始终调用这个方法来立即释放资源。示例：录音和播放录音这个例子的类演示了如何建立、启动和终止音频采集，并且播放录音文件。/* * The application needs to have the permission to write to external storage * if the output file is written to the external storage, and also the * permission to record audio. These permissions must be set in the * applications AndroidManifest.xml file, with something like: * * * * */package com.android.audiorecordtest;import android.app.Activity;import android.widget.LinearLayout;import android.os.Bundle;import android.os.Environment;import android.view.ViewGroup;import android.widget.Button;import android.view.View;import android.view.View.OnClickListener;import android.content.Context;import android.util.Log;import android.media.MediaRecorder;import android.media.MediaPlayer;import java.io.IOException;public class AudioRecordTest extends Activity private static final String LOG_TAG = AudioRecordTest; private static String mFileName = null; private RecordButton mRecordButton = null; private MediaRecorder mRecorder = null; private PlayButton mPlayButton = null; private MediaPlayer mPlayer = null; private void onRecord(boolean start) if (start) startRecording(); else stopRecording(); private void onPlay(boolean start) if (start) startPlaying(); else stopPlaying(); private void startPlaying() mPlayer = new MediaPlayer(); try mPlayer.setDataSource(mFileName); mPlayer.prepare(); mPlayer.start(); catch (IOException e) Log.e(LOG_TAG, prepare() failed); private void stopPlaying() mPlayer.release(); mPlayer = null; private void startRecording() mRecorder = new MediaRecorder(); mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC); mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP); mRecorder.setOutputFile(mFileName); mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB); try mRecorder.prepare(); catch (IOException e) Log.e(LOG_TAG, prepare() failed); mRecorder.start(); private void stopRecording() mRecorder.stop(); mRecorder.release(); mRecorder = null; class RecordButton extends Button boolean mStartRecording = true; OnClickListener clicker = new OnClickListener() public void onClick(View v) onRecord(mStartRecording); if (mStartRecording) setText(Stop recording); else setText(Start recording); mStartRecording = !mStartRecording; ; public RecordButton(Context ctx) super(ctx); setText(Start recording); setOnClickListener(clicker); class PlayButton extends Button boolean mStartPlaying = true; OnClickListener clicker = new OnClickListener() public void onClick(View v) onPlay(mStartPlaying); if (mStartPlaying) setText(Stop playing); else setText(Start playing); mStartPlaying = !mStartPlaying; ; public PlayButton(Context ctx) super(ctx); setText(Start playing); setOnClickListener(clicker); public AudioRecordTest() mFileName = Environment.getExternalStorageDirectory().getAbsolutePath(); mFileName += /audiorecordtest.3gp; Override public void onCreate(Bundle icicle) super.onCreate(icicle); LinearLayout ll = new LinearLayout(this); mRecordButton = new RecordButton(this); ll.addView(mRecordButton, new LinearLayout.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT, 0); mPlayButton = new PlayButton(this); ll.addView(mPlayButton, new LinearLayout.LayoutParams( ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams