Develop Reference

MediaPlayer always repeats after 1 second

I have an mp3 file that should be played repeatedly.
I simply use this code:
mediaPlayer = MediaPlayer.create(_context, scanner);
mediaPlayer.setLooping(true);
mediaPlayer.start();
I have tested it on Android Studio simulator and it works fine, then I have tested it on my own phone and it works fine as well BUT when I connect my phone with a speaker device over Bluetooth, the sound will be played well at the first time but when it's getting replayed, it always starts after about 1 second. The duration of my mp3 file is 4 seconds. So there is always 1 second that is missing.
I have no idea what the reason for that issue could be. Is it because of my code? My speaker device? Bluetooth connection? What is it?

This may solve your issue its a bit roundabout because it creates a new MediaPlayer per loop. Not able to achieve Gapless audio looping so far on Android Its seems like this issue has been a thing for a while. If you don't want to do this you may want to explore using another library instead of MediaPlayer

How to use front and back camera at the same time?

I want to use both front and back cameras at the same time. I have used two surface views. I have tried to implement the code in following answer.
https://stackoverflow.com/a/24238301/6874315
The problem is that the camera API is now deprecated and the code was too old. I tried using the Camera 2 API in the same way but the camera instance won't open and i get a blank white screen.
I get the following two errors:
Camera 0 not available! java.lang.RuntimeException: Fail to connect to camera service
Camera 1 not available! java.lang.RuntimeException: Fail to connect to camera service
What i wanna do is capture picture from front and back camera simultaneously on a button click. But i'm not able to open both front and back cameras at the same time.
Is there anything that I do to use both cameras at same time?

Take a look at these answers:
https://stackoverflow.com/a/30444841/11338123
https://stackoverflow.com/a/52075569/11338123
I think it is possible in some devices and it is impossible in others

I don't sure that it is possible to use both cameras simultaneously. But, you could switching between two cameras like in this sample for short time interval.
Also you can modify you program to process camera images in the background thread in such way to avoid GUI freezing.
So, you may try to make a little changes in the sample to get front and back camera instances for testing your idea. Good luck!

Why sometimes my Android App restart without a logic explanation?

I'm developing a scientific app in Android Studio. It works smoothy.
The set of source code files is not small, but, as I don't have practically user interface, there is only one activity and there is no intent.
All initialization code is inside OnCreate. Most of times, my app preserves all data, when he gets out of the foreground.
However, maybe (I cannot find a pattern of this event) he loses all data and restart (shows a white screen for 2 / 3 seconds), even if the cell phone don't enter in lock screen and there are just 2 apps running.
There are situations that I comute for another app (like WhatsApp) and resumes for my app, and my data was gone. The app restart again.
There is no error message, no logcat. Nothing.
Mostly, when I lock the screen and enter again, all my app data is there.
PS: My orientation is locked.
PS 2: I've read all related question and there is no hint for me. Based in one answer, I've tried to put in onCreate the following code.
if (!isTaskRoot() {
&& getIntent().hasCategory(Intent.CATEGORY_LAUNCHER)
&& getIntent().getAction() != null
&& getIntent().getAction().equals(Intent.ACTION_MAIN)) {
finish();
return;
}
No changes for me.
Update:
I've stumbled in solution. it can be read in my own answer. it's related to undesired back button effect for one-activity-app (read here and here ).
For me, as my application has only one activity, back needs to be like a home button: exit the app but preserve all activity data. My app has a real exit button, where the user shows that really wants to do this.

It's my first app that I developing in mobile world and, for extension, Android world
Some problems seems to me like that it is only possible find the solution if one has a hint about its solution. it's a contradiction. One doesn't know but has to know to solve that don't know!
And, in this situation, it's not the case. No hints. Just question marks.
Before, I had not noticed any pattern. People sometimes act so automatically ... However, suddenly the penny dropped.
I've stumbled in solution. Fortunately!
Not in a million years could I suppose that if someone has an activity and presses Back button, (right button in the bottom), you practically quit the application, even if it remains as a running app for the left button in the bottom (app switcher button)
When I've noticed it, I start to research with another focus. And I've discovered two sources: Disable back button in android and Android - Simulate Home click
So the solution is simply to make the Back button act like the Home button (middle button in the bottom). Return to the home screen without losing application data.
And this is done simply by putting in the onCreate, for my only activity, the following code.
override fun onBackPressed() {
val i = Intent(Intent.ACTION_MAIN)
i.addCategory(Intent.CATEGORY_HOME)
startActivity(i)
}

App crashing after sleeping

I'm currently following some video tutorials on Android development, and it's gone fine up until the 8th tutorial, we make a splash screen, and after 2 seconds it's supposed to go to the main application. The problem is, after 2 seconds, the screen goes black and the app crashes.
Logcat Output
I followed the tutorial exactly as he did it, the only difference with mine is that I'm developing for 4.2 instead of 2.2.
I'm also using my Galaxy Note 2 instead of an emulator to test.
I did it all as he did, and pressed play, the app opened on my device and the splash screen was there for 2 seconds (i set it to 2000) and then the spinner (which I added) freezes. The screen goes black, and then it crashes and says "Unfortunately, The Basic Series has stopped."
I've tried both sleep(2000) and Thread.sleep(2000).
Code for the AndroidManifest.xml and the main.java are here
If anyone is curious, this is the video I was following.

avoid splash screens except if u really need them to do some preparation operations..
avoid Thread sleep otherwise you will face ANR crashes (use post runnable with delay instead)
avoid reading this hint: What is your activity class name? Menu, menu, MENU or uNeM?
not so good tutorial IMHO
not honorable mention: if u really want to do it in this (btw not recommended way) check video at 8:48 and try to add catch clause and log exception.

If you need to do some initializations , use AsyncTask , or a thread that upon completion will use Activity.runOnUiThread (so that it won't crash when doing UI operations).
If you need to just show the splash screen and close it after some time , use Handler.postDelayed .
In all possible solutions , don't forget to cancel them upon onPause/onDestroy (depending on what you do/need) , so that if the user has left the app (exited or left it in the background) , it won't open up with the new activity when he resumes it (or worse , show it while it has gone to the background) .

PulpCore music playback - loop sound and animate volume

I have been experimenting with PulpCore, trying to create my own tower defence game (not-playable yet), and I am enjoying it very much I ran into a problem that I can't quite figure out. I extended PulpCore with the JOrbis thing to allow OGG files to be played. Works fine. However, pulpCore seems to have a problem with looping the sound WHILE animating the volume level. I tried this with wav file too, to make sure it isn't jOrbis that breaks it. The code is like this:
Sound bgMusic = Sound.load("music/music.ogg");
Playback musicPlayback;
...
musicVolume = new Fixed(0.75);
musicPlayback = bgMusic.loop(musicVolume);
//TODO figure out why it's NOT looping when volume is animated
// musicVolume.animate(0, musicVolume.get(), FADE_IN_TIME);
This code, for as long as the last line is commented out, plays the music.ogg again and again in an endless loop (which I can stop by calling stop on the Playback object returned from loop(). However, I would like the music to fade in smoothly, so following the advice of the PulpCore API docs, I added the last line which will create the fade-in but the music will only play once and then stop. I wonder why is that? Here is a bit of the documentation:
Playback
pulpcore.sound.Sound.loop(Fixed level)
Loops this sound clip with the
specified volume level (0.0 to 1.0).
The level may have a property
animation attached.
Parameters: level
Returns: a Playback object for this
unique sound playback (one Sound can
have many simultaneous Playback
objects) or null if the sound could
not be played.
So what could be the problem? I repeat, with the last line, the sound fades in but doesn't loop, without it it loops but starts with the specified 0.75 volume level.
Why can't I animate the volume of the looped music playback? What am I doing wrong? Anyone has any experience with pulpCore and has come across this problem? Anyone could please download PulpCore and try to loop music which fades-in (out)?
note: I need to keep a reference to the Playback object returned so I can kill music later.

If the animate method only sets the option, it can work unpredictably - try switching this line with the loop itself, so the animation applies first.

Can you animate the volume on an unlooped playback, and then, at the end of that playback, start the loop at the fixed level?

Finally I managed to get an explanation and a simple work-around for this issue from the pulp core author. So here it is:
It is a PulpCore bug. When the output
volume is zero, the sound player stops
looping the sound.
To work around it, animate from a
value that is not zero, like this:
musicVolume.animate(0.0001, 1, FADE_IN_TIME);
Link to this on pulpcore Google groups