I'm writing an Android music player, and is stuck on audio focus issue.
It seems like audio focus mainly affects media button receiving, but after reading the document I have no idea about when to gain and give up focus.
My music app will run in background, and need to detect play/pause button every time. That is, even when my app is not running, a user should be able to press headset's play button and start music.
It seems I should never give up audio focus, so why should I implement it?
Does anyone know practically how audio focus should be used? Thank you!
It seems like audio focus mainly affects media button receiving, but
after reading the document I have no idea about when to gain and give
up focus.
They both are separate functionalities, and thus have separate listeners. You may have audio focus taken away from you but you may still choose to respond to play pause hardware keys
That is, even when my app is not running, a user should be able to
press headset's play button and start music.
I am assuming that you meant by the above line is that you are still playing music but not showing an activity. To keep listening to hardware button press, dont unregister your media button receiver(dont call audioManager.unregisterMediaButtonEventReceiver(receiver) yet).
It seems I should never give up audio focus, so why should I implement
it?
you dont give up the focus , it gets taken from you. To handle that gracefully you have AudioFocus listener. For ex, consider an incoming phone call. Would you still like to continue playing your music?
Related
I have been reading the Android documentation on "Audio Focus", and the best-practices they lay out, but one thing alludes me...
Games need music pretty much the whole time, so it makes sense to request Audio Focus OnStart, but this can lead to a bad user experience.
If my App requests Audio Focus, and something is currently playing music already (eg. Samsung Music Player), my request will forcefully stop their music. The only special case I know of is if you request Audio Focus while the user is in a Phone Conversation.
I think what the user expects to happen, is if they are not already listening to music (or podcast, or whatever), then the game music should play. However, if they are already listening to their own music, then the game should not play music (but still play sound effects).
This is how things work on Xbox, Windows Phone, PS3, etc.
Is this just how it is on Android? Has anyone come up with a nice work around?
Note: I am familiar with AudioManager.IOnAudioFocusChangeListener. I am speaking specifically about the initial request for Audio Focus.
The other special case to avoid stopping something from playing when requesting audio focus is to allow it to duck, but that applies to transient loss which isn't what you would be doing. There's no way to know if another app is playing audio unfortunately so you will either take the audio and kill the music or you can not request the audio and hope for the best.
It might be worth prompting the user on launch if they are listening to their own music and if so then your game music will remain silent.
In my application I want to get start time of music player when user started and end time when it stops.I don't want to start any music player in my app. I just want to track user activity in device. So i want my application to get any notification when user started the music .
Do I get any intent for music player started and it stopped.Or do I get any intent for when user opens music files.
Is there any other method other than intent to capture the start time and and time when user starts music player.
Well you can implement the interface 'AudioManager.OnAudioFocusChangeListener' in which there is a method 'onAudioFocusChange' which lets you know if audio focus has been changed, and it can also tell if focus was gained or lost.
See this link, it explains the Audio Focus in detail. An application must gain audio focus through a request, and you can implement the 'AudioManager.OnAudioFocusChangeListener' and if there is focus gain, you can detect if the media player is running, (because some other application such as you tube may gain focus to play its audio), see this to see how to detect which application or service is currently running. You can find if audio has started to play, and if it was the media player or not.
Hope this helps. It was interesting question and I have learned some new things while searching for the answer!
I play a song in background, and the screen is off now. I press the volume key, the volume of the music stream changes. How can it happen? I have searched for a long time for a solution about how to detect the volume keys press event when screen off, but I don't know how to solve the problem so far.
you need a BroadcastReceiver that listens to the according broadcasts. see a similar question here.
If you wish to control the volume of audio played through your app, make use of setVolumeControlStream() method. It directs volume key presses to the audio stream you specify.
setVolumeControlStream(AudioManager.STREAM_MUSIC);
I'm playing some music from a service with Androids MediaPlayer. When the music is playing, the music volume can be changed by the volume rocker keys. However I don't want that the user can change the music volume during playback.
How can this be done?
It is possible when getting the keydown event and returning true, but that only works when the app is on top. Since I play the music from a service, it is also played when the screen is off or the app in background, so the volume can still be changed.
Another idea I had is to call
setVolumeControlStream( AudioManager.STREAM_RING );
after having started playing the music, but I can't call this from a service but only from an activity...
Or is it possible to play the music on another stream (Ring or alarm), but let the volume rocker still change the music stream?
Any ideas?
'You cannot intercept the key while your application is in background, but instead of listening to the KeyPress itself. You can register a ContentObserver'
Is there a broadcast action for volume changes?
Since I haven't found another way to do it, I check in a timer about 5 times per second if the volume has been changed. If it has, I change it back.
This is a really ugly solution, but it works and if there is no other way to do it, I have to leave it like this.
The only really horrible thing is that the volume dialog shows up when you press the volume rocker. Is there a way to disable the volume dialog?
Or do you know a better solution?
I am trying to figure out what is the correct (new) approach for handling the Intent.ACTION_MEDIA_BUTTON in Froyo. In pre 2.2 days we had to register a BroadcastReceiver (either permanently or at run-time) and the Media Button events would arrive, as long as no other application intercepts them and aborts the broadcast.
Froyo seems to still somewhat support that model (at least for the wired headset), but it also introduces the registerMediaButtonEventReceiver, and unregisterMediaButtonEventReceiver methods that seem to control the "transport focus" between applications.
During my experiments, using registerMediaButtonEventReceiver does cause both the bluetooth and the wired headset button presses to be routed to the application's broadcast receiver (the app gets the "transport focus"), but it looks like any change in the audio routing (for example unplugging the headset) shits the focus back to the default media player.
What is the logic behind the implementation in Android 2.2? What is correct way to handle transport controls? Do we have to detect the change in the audio routing and try to re-gain the focus?
This is an issue that any 3rd party media player on the Android platform has to deal with, so I hope that somebody (probably a Google Engineer) can provide some guidelines that we can all follow. Having a standard approach may make headset button controls a bit more predictable for the end users.
Stefan
Google has a detailed blog post on implementing the newer 2.2 AudioManager media button event receiver while maintaining backwards compatibility with older devices.
http://android-developers.blogspot.com/2010/06/allowing-applications-to-play-nicer.html
After some experiments, I was able to get a working solution with the new transport and audio focus infrastructure in Android 2.2.
What I end up doing is requesting both the Audio Focus (using AudioManager.requestAudioFocus) and the Trasport Focus (using AudioManagter.registerMediaButtonEventReceiver) every time my application starts playback.
requestAudioFocus takes a callback that is called when the audio focus is taken away from you (for example the internal player starts a playback). In my case I just pause the playback in my application if the focus is taken permanently. Same callback also now tells you that the focus is taken only temporary (for example the Nav system is talking) so you can "duck" your playback - lower the volume or pause and resume after it is done talking.
The only issue remaining is that the built in Music Player takes the transport focus every time you connect a Bluetooth headset. This has the effect where the first press of the Play button on the headset after connecting it, always starts the playback in the default Music Player.
There is probably a way to detect the headset connection and "hijack" the transport focus. In my case, I decided to not "fight" the default player, and get the transport focus back when the user manually starts the playback in my application.
If somebody has more insight or knows of a better way of handling the transport/audio focus, please share it.
I also have this same issue with the media button registration.
Periodically the Android returns the media button registration to the default music player. I have not been able to figure out why. This can happen while may application is actively playing as well as while my application playback is paused.
After a number of users complained that their Bluetooth pause and play control buttons would periodically stop working to control my application, I implemented code that re-registers my application by calling registerMediaButtonEventReceiver every 2 seconds. This allows me to get the button registration back and for the most part avoids the time window where where the user presses a Bluetooth media button and the default media player ends up responding.
My application is holding the audio focus during this entire time period, but still loses the Bluetooth button events periodically while it has audio focus. My application always unregisters the media button event receiver if it is called with a notification that it is losing the audio focus, and then registers again if it is later called when a temporary audio focus loss returns the audio focus.
The work around to keep the 2 second timer running and re-registering has been working, but I would like to get rid of this 2 second timer if someone has found a work around for the media button registration periodically switching back to the default media player.