Android(安卓)API Guides---Audio Capture

Android的多媒体框架包括用于捕获和编码多种常见的音频格式，让你可以轻松的音频集成到应用程序的支持。使用MediaRecorder的API如果由设备硬件支持，您可以录制音频。
本文向您介绍如何编写从设备麦克风捕获音频的应用，保存音频回放。
注意：Android模拟器不必捕获音频的能力，但实际的设备有可能提供这些功能。
执行音频捕获
从设备音频采集是有点比音频和视频播放更复杂，但仍然相当简单：
创建android.media.MediaRecorder的新实例。
设置使用MediaRecorder.setAudioSource音频源（）。你可能会想使用MediaRecorder.AudioSource.MIC。
使用MediaRecorder.setOutputFormat设置输出文件格式（）。
使用MediaRecorder.setOutputFile设置输出文件名（）。
设置使用MediaRecorder.setAudioEncoder音频编码器（）。
所谓MediaRecorder.prepare（）在MediaRecorder实例。
要启动音频采集，调用MediaRecorder.start（）。
要停止音频采集，调用MediaRecorder.stop（）。
当你与MediaRecorder实例来完成，它调用MediaRecorder.release（）。调用MediaRecorder.release（）总是建议立即释放资源。
例如：录制音频和播放录制的音频

下面的例子说明了类如何设置，启动和停止音频采集和播放录制的音频文件。

/** 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* application's AndroidManifest.xml file, with something like:** <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />* <uses-permission android:name="android.permission.RECORD_AUDIO" />**/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.WRAP_CONTENT,        0));    setContentView(ll);  }  @Override  public void onPause() {    super.onPause();    if (mRecorder != null) {      mRecorder.release();      mRecorder = null;    }    if (mPlayer != null) {      mPlayer.release();      mPlayer = null;    }  }}

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