Android音频采集
jopen
12年前
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 * 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; } } }