Develop Reference

MediaPlayer audio playing stops when app enters in background (OREO)

I have a manager class with an array of MediaPlayer instances which is the manager for playing audio on my app. Until now, it worked perfectly in background and keep playing the audio when the device is blocked.
Now, starting with Oreo devices, the audio playing stops. Is there an easy way of forcing the device to keep alive the MediaPlayer instance which is playing the audio? I mean a simple way without using services or without creating custom bars on the notification bar of the device, which are the options I found for now here in Stack Overflow. Probably must be a simpler way.
This is the code I used to play an audio until now:
MediaPlayer mPlayer = new MediaPlayer();
AssetFileDescriptor fileDescriptor = ApplicationContextProvider.getContext().getAssets().openFd(res.getUrl());
long start = fileDescriptor.getStartOffset();
long end = fileDescriptor.getLength();
mPlayer.setDataSource(fileDescriptor.getFileDescriptor(), start, end);
mPlayer.prepareAsync();
mPlayer.setOnPreparedListener(new OnPreparedListener() {
#Override
public void onPrepared(MediaPlayer mp) {
mp.start();
}
});
mPlayer.setLooping(loop);
fileDescriptor.close();

Use foreground Serive. For details on why the service will no longer work watch
https://www.youtube.com/watch?v=Pumf_4yjTMc
It clearly says that background services will be stopped. For tutorial on Foreground Services watch:
https://www.youtube.com/watch?v=FbpD5RZtbCc
Remember you would also need to learn the notification channels starting Oreo. This guy has introduced that too.

Android interrupt media player with ringtone manager

I have used ringtonemanager previously in android studio and it seemed to lower the volume of any music that was playing in a different app to play the alert i was trying to play, then once my alert had completed the background music would then come back to normal volume (as the default alarm/notification would do) But now a year or so later im trying to implement this again but my alert cannot be heard over the music playing in Google Play Music.
Is this a change that now requires additional parameters to function as it used to?
Im using:
Uri notification =
RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM);
myRM = RingtoneManager.getRingtone(this.getContext(), notification);
myRM.play();
Many Thanks

Handling Changes in Audio Output seems what fits your need.
In short, you need to request audio focus before starting playing.
...
mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
mAudioManager.requestAudioFocus(null, mStreamType, AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK);
mRingtone.play();
AUDIOFOCUS_GAIN_TRANSIENT_MAY_DUCK
Used to indicate a temporary request of audio focus, anticipated to
last a short amount of time, and where it is acceptable for other
audio applications to keep playing after having lowered their output
level (also referred to as "ducking").
Remember to release audio focus when finishing..
if (mRingtone != null && mRingtone.isPlaying()) {
mRingtone.stop();
}
mRingtone = null;
if (mAudioManager != null) {
mAudioManager.abandonAudioFocus(null);
}

How to play sounds at accurate periods of time across different devices in Android

I'm developing a game in Android and I came across a very annoying, hard-to-find bug. The issue is that when you are using SoundPool to play your sounds, you can actually loop whatever sound you are playing. In this case, the issue is the "running steps" sound; this sound gets executed quite fast and continually (around every 400ms) when the main character is running.
Now when playing the sound on a regular (not so powerful) device e.g. Samsung SII, the sound is played every 500ms - however, if I run the very same code on another device (let's say, Samsung SIV, Samsung SIII), the sound plays twice or even three times faster.
It seems like the more powerful the device hardware specs are, the faster it plays. On some devices, it plays so fast that you almost hear one solid continuous sound. I've been looking for techniques to set a specific ratio on the time period between sound plays, but it doesn't work properly and the issue remains. Does anyone know how to fix it, either using SoundPool, MediaPlayer, or any other sound-controlling API on Android?

You could use an AudioTrack to play a continuous stream of PCM data, since you would pass a stream you could be sure about the interval between sounds. the downside could be a little delay when first starting the sound but it depends on the minimum buffer size, and it depends, I think, on android version and device. On my galaxy s2 android 4.1 it was about 20ms.if you think this could be an option I can post some code

The problem with just looping or using a regular interval for something like footsteps is that you have a possible decoupling of sound and visuals. If your sound gets delays or sped up, or your visuals get delayed or sped up, you would have to adjust for that delay dynamically and automatically. You already have that issue right here
A better solution would be to place a trigger on the exact event which should trigger the sound (in this case, the foot being placed down), which then plays the sound. This also means that if you have multiple sources of the sound (like multiple footsteps), you don't have to manually start the sound with the right interval.

I can't seem to replicate the issue on Galaxy Nexus and Nexus S, does that mean I fixed it? Or maybe you could show what you're doing differently from this:
SoundPool soundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 100);
Integer sound1 = soundPool.load(this, R.raw.file1, 1);
Integer sound2 = soundPool.load(this, R.raw.file2, 1);
playSound(sound1);
public void playSound(int sound) {
AudioManager mgr = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
float volume = mgr.getStreamVolume(AudioManager.STREAM_MUSIC)
/ mgr.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
soundPool.play(sound, volume, volume, 1, -1, 1.0f);
}

If the problem is that you want to control the interval between the discrete sounds, The easiest way to do this is with a handler.
Basically you start a sound playing which is an asynchronous process. Then you use a handler to schedule a message to play the next sound sometime in the future. It will take some trial and error to get it right, but you will be guaranteed that the sound will start at the same interval after the previous sound on every device.
Here is some code to illustrate what I am talking about.
Here is a handler implementation you could use:
handler = new Handler() {
/* (non-Javadoc)
* #see android.os.Handler#handleMessage(android.os.Message)
*/
#Override
public void handleMessage(Message msg) {
if (msg.what == NEXT_ITEM_MSG) {
playNextSound();
}
else if (msg.what == SEQUENCE_COMPLETE_MSG) {
// notify a listener
listener.onSoundComplete()
}
}
};
Then you could write playNextSound like this:
private void playNextSound() {
if (mRunning) {
// Get the first item
SoundSequenceItem item = currentSequence.getNextSequenceItem();
if (item == null) {
Message msg = handler.obtainMessage(SEQUENCE_COMPLETE_MSG);
handler.sendMessage(msg);
return;
}
// Play the sound
int iSoundResId = item.getSoundResId();
if (iSoundResId != -1) {
player.playSoundNow(soundResId);
}
// schedule a message to advance to next item after duration
Message msg = handler.obtainMessage(NEXT_ITEM_MSG);
handler.sendMessageDelayed(msg, item.getDuration());
}
}
and your SoundSequenceItem could just be a simple class that has a sound file resource id and a duration. If you want to keep playing the sound while the character is moving you could do something like this:
public void onSoundComplete() {
if (character.isRunning()) {
currentSequence.addSequenceItem(new SoundSequenceItem(R.id.footsteps,500);
playNextSound();
}
}
Or you could modify playNextSound to continually play the same sound. Mine is written this way to be able to play different sounds in sequence.

I have had a lot of problems developing apps which used sounds and stuff like that. I would not suggest you to use SoundPool since it is bug-affected, and also be aware that looping sounds with SoundPool won't work on devices which are 4.3 and higher, see this open issue, at AOSP - Issue tracker.
I think that the solution is to go native and use OpenSL ES o similar libraries.

Volume Channels

Such Problem: I have video file recorded with two sound channels. I tried to switch off left sound channel by this code:
MediaPlayer mp;
....
mp.setVolume(0.f, 1f);
... and on Tablet this work good (right volume channel sounds well). But then I tried it on googleTv which I connect to Samsung UE46ES6307U and this code did not work, sound swichs off.
Maybe it is bounds to Dolby Digital Plus / Dolby Pulse audio? Can I somehow programmatically discover how sound channels device has, and what volume in each chanels setuped?
Update:
On this forum http://www.googletvforum.org/forum/logitech-revue/375-audio-problems-logitech-revue.html in one of replies such message: "Logitech has not yet figured out how to pipe multichannel audio thru hdmi.you have to use the optical output. Which is ok."
"How are you constructing the MediaPlayer?"
Videoview vv;
...............
vv.setOnPreparedListener(new OnPreparedListener() {
#Override
public void onPrepared(MediaPlayer mp) {
mp.setVolume(0.f, 1f);
}
});
Update:
public class MainActivity extends Activity {
MediaPlayer mp = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (mp != null) {
mp.reset();
mp.release();
}
mp = MediaPlayer.create(this, R.raw.test);
mp.start();
}
public void onTurnOffLeft(View v){
mp.setVolume(0.f, 1.f);
}
public void onTurnOffRight(View v){
mp.setVolume(1.f, 0.f);
}
}
Method onTurnOffLeft switchs off all sound, and onTurnOffRight method has no effect.
Update2
I tried to play .ogg audio file codded with Vorbis codec - channels turns off well. But I tried to play video files codded with mp3, ac3, pcm, aac - and problem with turning off channels is still there... I need to turn off audio channels in video, but how to solve that problem, I do not know yet.

The MediaPlayer object is backed by different libraries across the devices (not the same between a tablet and a Google TV). How are you constructing the MediaPlayer?
One thing you may want to try is calling #reset() on the MediaPlayer right after it is constructed. By default when you use a "new" operator to construct a MediaPlayer instance it is in an IDLE state (at least on Google TV). By calling reset you allow your own OnErrorListener.onError() handler to be invoked. This will let you see if there is some underlying error that is not visible otherwise.
You may also want to look at AudioManager#setStreamVolume(int, int, int) which sets the volume of ALL streams of a particular type.
Edit 1:
Since you are just grabbing the VideoView from layout (I'm guessing since that code was omitted) after you setup the listener you should call reset on the video view.

Android - is it possible to find out which app has audiofocus?

There's an app on my phone that keeps taking audio focus, even when no sound is playing. I'm wondering as an app developer if I'd be able to inform the user which app it is, or if I can tell if my app has audio focus?

I strongly doubt that there is any public APIs can tell you which app having the focus at the moment.
You can keep track if your app has the audio focus by requesting it, e.g.:
AudioManager audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
boolean requestGranted = AudioManager.AUDIOFOCUS_REQUEST_GRANTED == audioManager.requestAudioFocus(listener, AudioManager.STREAM_MUSIC,
AudioManager.AUDIOFOCUS_GAIN);
if(requestGranted){
// you now has the audio focus
}
You should make sure to maintain a single instance of your listener when you request and abandon focus, see my answer here to troubleshoot common problems with audio focus
Here is an example of onAudioFocusChange():
#Override
public void onAudioFocusChange(int focus) {
switch (focus) {
case AudioManager.AUDIOFOCUS_LOSS:
Log.d(TAG,"AUDIOFOCUS_LOSS");
// stop and release your player
break;
case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT:
Log.d(TAG,"AUDIOFOCUS_LOSS_TRANSIENT");
// pause your player
break;
case AudioManager.AUDIOFOCUS_GAIN:
Log.d(TAG,"AUDIOFOCUS_GAIN");
// restore volume and resume player if needed
break;
case AudioManager.AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK:
Log.d(TAG,"AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK");
// Lower volume
break;
}
}

Maybe this method does what you want:
AudioManager.isMusicActive()
http://developer.android.com/reference/android/media/AudioManager.html#isMusicActive%28%29