Handling the AUDIO_BECOMING_NOISY Intent
Many well-written applications that play audio automatically stop playback when an event occurs that causes the audio to become noisy (ouput through external speakers). For instance, this might happen when a user is listening to music through headphones and accidentally disconnects the headphones from the device. However, this behavior does not happen automatically. If you don't implement this feature, audio plays out of the device's external speakers, which might not be what the user wants.You can ensure your app stops playing music in these situations by handling the
ACTION_AUDIO_BECOMING_NOISY
intent, for which you can register a receiver by adding the following
to your manifest:<receiver android:name=".MusicIntentReceiver"> <intent-filter> <action android:name="android.media.AUDIO_BECOMING_NOISY" /> </intent-filter> </receiver>This registers the
MusicIntentReceiver
class as a broadcast receiver for that intent. You should then
implement this class:public class MusicIntentReceiver implements android.content.BroadcastReceiver {
@Override
public void onReceive(Context ctx, Intent intent) {
if (intent.getAction().equals(
android.media.AudioManager.ACTION_AUDIO_BECOMING_NOISY)) {
// signal your service to stop playback
// (via an Intent, for instance)
}
}
}
Retrieving Media from a Content Resolver
Another feature that may be useful in a media player application is the ability to retrieve music that the user has on the device. You can do that by querying theContentResolver
for external media:ContentResolver contentResolver = getContentResolver();
Uri uri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
Cursor cursor = contentResolver.query(uri, null, null, null, null);
if (cursor == null) {
// query failed, handle error.
} else if (!cursor.moveToFirst()) {
// no media on the device
} else {
int titleColumn = cursor.getColumnIndex(android.provider.MediaStore.Audio.Media.TITLE);
int idColumn = cursor.getColumnIndex(android.provider.MediaStore.Audio.Media._ID);
do {
long thisId = cursor.getLong(idColumn);
String thisTitle = cursor.getString(titleColumn);
// ...process entry...
} while (cursor.moveToNext());
}
To use this with the MediaPlayer,
you can do this:long id = /* retrieve it from somewhere */; Uri contentUri = ContentUris.withAppendedId( android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, id); mMediaPlayer = new MediaPlayer(); mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mMediaPlayer.setDataSource(getApplicationContext(), contentUri); // ...prepare and start..
JetPlayer
The Android platform includes a JET engine that lets you add
interactive playback of JET audio content in your applications. You
can create JET content for interactive playback using the JetCreator
authoring application that ships with the SDK. To play and manage JET
content from your application, use the
JetPlayer
class.Playing JET content
This section shows you how to write, set up and play JET content. For a description of JET concepts and instructions on how to use the JetCreator authoring tool, see the JetCreator User Manual. The tool is available on Windows, OS X, and Linux platforms (Linux does not support auditioning of imported assets like with the Windows and OS X versions).Here's an example of how to set up JET playback from a
.jet
file stored on the SD card:JetPlayer jetPlayer = JetPlayer.getJetPlayer();
jetPlayer.loadJetFile("/sdcard/level1.jet");
byte segmentId = 0;
// queue segment 5, repeat once, use General MIDI, transpose by -1 octave
jetPlayer.queueJetSegment(5, -1, 1, -1, 0, segmentId++);
// queue segment 2
jetPlayer.queueJetSegment(2, -1, 0, 0, 0, segmentId++);
jetPlayer.play();
The SDK includes an example application — JetBoy — that shows how
to use JetPlayer
to create an interactive music soundtrack in your game. It also
illustrates how to use JET events to synchronize music and game
logic. The application is located at JetBoy
Audio Capture
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.
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;
}
}
}
Performing Audio Capture
Audio capture from the device is a bit more complicated than audio and video playback, but still fairly simple:- Create a new instance of
android.media.MediaRecorder. - Set the audio source using
MediaRecorder.setAudioSource(). You will probably want to useMediaRecorder.AudioSource.MIC. - Set output file format using
MediaRecorder.setOutputFormat(). - Set output file name using
MediaRecorder.setOutputFile(). - Set the audio encoder using
MediaRecorder.setAudioEncoder(). - Call
MediaRecorder.prepare()on the MediaRecorder instance. - To start audio capture, call
MediaRecorder.start(). - To stop audio capture, call
MediaRecorder.stop(). - When you are done with the MediaRecorder instance, call
MediaRecorder.release()on it. CallingMediaRecorder.release()is always recommended to free the resource immediately.
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