topics/media/audio-capture.jd

page.title=Audio Capture
parent.title=Multimedia and Camera
parent.link=index.html
@jd:body

    <div id="qv-wrapper">
    <div id="qv">

<h2>In this document</h2>
<ol>
<li><a href="#audiocapture">Performing Audio Capture</a>
   <ol>
      <li><a href='#example'>Code Example</a></li>
   </ol>
</li>
</ol>

<h2>Key classes</h2>
<ol>
<li>{@link android.media.MediaRecorder}</li>
</ol>

<h2>See also</h2>
<ol>
  <li><a href="{@docRoot}guide/appendix/media-formats.html">Android Supported Media Formats</a></li>
  <li><a href="{@docRoot}guide/topics/data/data-storage.html">Data Storage</a></li>
  <li><a href="{@docRoot}guide/topics/media/mediaplayer.html">MediaPlayer</a>
</ol>

</div>
</div>

<p>The Android multimedia framework includes support for capturing and encoding a variety of common
audio formats, so that you can easily integrate audio into your applications. You can record audio
using the {@link android.media.MediaRecorder} APIs if supported by the device hardware.</p>

<p>This document shows you how to write an application that captures audio from a device
microphone, save the audio and play it back.</p>

<p class="note"><strong>Note:</strong> The Android Emulator does not have the ability to capture
audio, but actual devices are likely to provide these capabilities.</p>

<h2 id="audiocapture">Performing Audio Capture</h2>

<p>Audio capture from the device is a bit more complicated than audio and video playback, but still
fairly simple:</p>
<ol>
  <li>Create a new instance of {@link android.media.MediaRecorder android.media.MediaRecorder}.</li>
  <li>Set the audio source using
        {@link android.media.MediaRecorder#setAudioSource MediaRecorder.setAudioSource()}. You will
probably want to use
  <code>MediaRecorder.AudioSource.MIC</code>.</li>
  <li>Set output file format using
        {@link android.media.MediaRecorder#setOutputFormat MediaRecorder.setOutputFormat()}.
  </li>
  <li>Set output file name using
        {@link android.media.MediaRecorder#setOutputFile MediaRecorder.setOutputFile()}.
  </li>
  <li>Set the audio encoder using
        {@link android.media.MediaRecorder#setAudioEncoder MediaRecorder.setAudioEncoder()}.
  </li>
  <li>Call {@link android.media.MediaRecorder#prepare MediaRecorder.prepare()}
   on the MediaRecorder instance.</li>
  <li>To start audio capture, call
  {@link android.media.MediaRecorder#start MediaRecorder.start()}. </li>
  <li>To stop audio capture, call {@link android.media.MediaRecorder#stop MediaRecorder.stop()}.
  <li>When you are done with the MediaRecorder instance, call
{@link android.media.MediaRecorder#release MediaRecorder.release()} on it. Calling
{@link android.media.MediaRecorder#release MediaRecorder.release()} is always recommended to
free the resource immediately.</li>
</ol>

<h3 id="example">Example: Record audio and play the recorded audio</h3>
<p>The example class below illustrates how to set up, start and stop audio capture, and to play the
recorded audio file.</p>
<pre>
/*
 * 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:
 *
 * &lt;uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /&gt;
 * &lt;uses-permission android:name="android.permission.RECORD_AUDIO" /&gt;
 *
 */
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";
    }

    &#64;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);
    }

    &#64;Override
    public void onPause() {
        super.onPause();
        if (mRecorder != null) {
            mRecorder.release();
            mRecorder = null;
        }

        if (mPlayer != null) {
            mPlayer.release();
            mPlayer = null;
        }
    }
}
</pre>