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Android.com

Multimedia and Camera >

# Audio Capture

## In this document

1. Performing Audio Capture
   1. Code Example

## Key classes

1. `MediaRecorder`

## See also

1. Android Supported Media Formats
2. Data Storage
3. MediaPlayer

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 `MediaRecorder` APIs if supported by the device hardware.

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

Note: The Android Emulator does not have the ability to capture audio, but actual devices are likely to provide these capabilities.

## Performing Audio Capture

Audio capture from the device is a bit more complicated than audio and video playback, but still fairly simple:

1. Create a new instance of `android.media.MediaRecorder`.
2. Set the audio source using `MediaRecorder.setAudioSource()`. You will probably want to use `MediaRecorder.AudioSource.MIC`.
3. Set output file format using `MediaRecorder.setOutputFormat()`.
4. Set output file name using `MediaRecorder.setOutputFile()`.
5. Set the audio encoder using `MediaRecorder.setAudioEncoder()`.
6. Call `MediaRecorder.prepare()` on the MediaRecorder instance.
7. To start audio capture, call `MediaRecorder.start()`.
8. To stop audio capture, call `MediaRecorder.stop()`.
9. When you are done with the MediaRecorder instance, call `MediaRecorder.release()` on it. Calling `MediaRecorder.release()` is always recommended to free the resource immediately.

### Example: Record audio and play the recorded audio

The example class below illustrates how to set up, start and stop audio capture, and to play the recorded audio file.

    /*
     * 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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