iOS AVAudioSession ducking is slow and synchronous - ios

In iOS, I'm trying to duck the Music app's music when playing some sound effects. In case you don't know, "ducking" simply means that the music volume gets a bit down before playing my sound, then the sound plays, and then the music volume gets back its initial volume.
For ducking, I'm setting AVAudioSession category to AVAudioSessionCategoryAmbient with option AVAudioSessionCategoryOptionDuckOthers, and then activating/deactivating the session (and playing the sound in-between, obviously). It works well, but the volume changes seem to be done in the same thread as the call, and the app hangs while the volume is being modified.
If you want to replicate the behavior, I think the fastest route is to start a new SpriteKit project, which will give you the sample, ship rotating project. Then put the following code in the touchesBegan:withEvent method:
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryAmbient withOptions: AVAudioSessionCategoryOptionDuckOthers error: nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
[[AVAudioSession sharedInstance] setActive:NO error:nil];
Next run the app in an iOS device, put some music in the Music app and touch the screen to create ships and duck the music. You'll hear the ducking, but also see the ships freezing on the screen.
Is this normal? What would be the simplest way to avoid the app freezing while the ducking is made?
By the way, I'm using an iPhone 5S on iOS 8.1. Also, I'm using this in a Unity3D plugin. How can I duck the Music app from Unity itself?

You can try putting the AVAudioSession calls on a different thread. Then they won't be blocking the main (UI) thread. This is especially for setActive, which takes a noticeable amount of time to complete.
dispatch_queue_t myQueue = dispatch_queue_create("com.myname.myapp", nil);
dispatch_async(myQueue, ^{
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryAmbient withOptions: AVAudioSessionCategoryOptionDuckOthers error: nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
});
This question also seems relevant: iOS AudioSessionSetActive() blocking main thread?

Related

How can you configure AVAudioSession to duck music and pause spoken audio?

I'm working on a navigation app that uses AVSpeechSynthesizer to call out directions. If I'm playing a podcast I would like to be able to pause the audio while a direction is spoken and resume it afterwards. This is successfully achieved using:
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback
withOptions:AVAudioSessionCategoryOptionInterruptSpokenAudioAndMixWithOthers
error:nil];
However, if I play music using the above code the instruction gets mixed with the music without the volume of the music being reduced - making it difficult to hear the instruction. So I tried:
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback
withOptions:AVAudioSessionCategoryOptionDuckOthers
error:nil];
Now the background music reduces in volume, which is what I want, but when I play spoken audio (i.e. a podcast) it is no longer paused and instead gets mixed with the instruction - albeit at a reduced volume.
What I really want is something like: AVAudioSessionCategoryOptionInterruptSpokenAudioAndDuckWithOthers. However, that doesn't exist. I know that this combination is possible, because other apps (like Waze) have this behaviour.
I know that you can detect when audio is playing using:
BOOL isOtherAudioPlaying = [[AVAudioSession sharedInstance] isOtherAudioPlaying];
But, I couldn't find a way of determining if that Audio was spoken or not. If I could I could set things up according to what is playing at any given time. Can anyone help with this, preferably in Objective C?
This is how it's done:
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback
withOptions:AVAudioSessionCategoryOptionDuckOthers | AVAudioSessionCategoryOptionInterruptSpokenAudioAndMixWithOthers
error:nil];
Works a charm!

iOS: Keep playing music in background with Spotify SDK

I'm using the Spotify iOS SDK and have a question about the background music.
When a user locks the phone or presses the Home button I want my app to continue to play the music. How is this possible?
I've tested
NSError *setCategoryErr = nil;
NSError *activationErr = nil;
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error:&setCategoryErr];
[[AVAudioSession sharedInstance] setActive:YES error:&activationErr];
Together with adding "Required background modes" to the apps plist.
Does this require that the AVAudioPlayer is used? Since I'm using the Spotify streamingPlayer its not possible.
Background playback should work just fine. You do need the audio item in your UIBackgroundModes Info.plist entry, though. Also, make sure you test on a device - I know remote control events don't work in the iOS Simulator, and that might be the case for background audio as well.
The iOS SDK will automatically set up the AVAudioSession for you, so you don't need to do that.
You might find this answer helpful, which is more in-depth: Background Audio with cocoalibspotify.

iOS MPMoviePlayerViewController stop playing when screen locks

I implement MPMoviePlayerViewController to play video and I enable airPlay and works great but the problem is when the screen on the ipad locks. My question is how can make sure the MPMoviePlayerViewController still in airPlay even when the screen locks. Any of you knows how can I make this work?
Where as Apple thinks that When user can't see the video what is the benefit to runs consistently? So there is no need to play Video when you can't see it. Apple pauses it when app goes to background or screen locks. If you still want to play it you can add notification to start and stop when you go to background and come to foreground.
Hope this helps.
In your Info.plist file, add the key "Required background modes" with the value "App plays audio or streams audio/video using AirPlay".
Also, when you receive the notification MPMoviePlayerIsAirPlayVideoActiveDidChangeNotification, add these lines:
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
And add this line to your dealloc method:
[[AVAudioSession sharedInstance] setActive:NO error:nil];

Deactivating avaudiosession after going back from videoviewcontroller

I am trying to play video in background everything works just fine and the video play and get pause normally in background.But the only problem is whenever I go back from the from my
videoviewcontroller(the view on which is played to menu), the video still remains in the background and you can see it as Musicplayer position. How can this be removed once I get out of videoviewcontroller
I have tried
NSError *error;
[[AVAudioSession sharedInstance] setActive:NO error:&error];
NSLog(#"ERROR: %#", error);
output
ERROR: (null)
this code removes the video from the background
[[AVAudioSession sharedInstance] setCategory:nil error:nil];
but if now if want to play the video again it will not play in background mode
From Apple's:AVAudioSession class documentation
It says
Deactivating your session will fail if any associated audio objects (such as queues, converters, players or recorders) are currently running.
So you need to stop any/all of this audio objects before calling the setActive:No
I had had similar issues while trying to perform this before stopping my audio queue.
In mi case I was using an external audio library (Dirac) and I just needed to call an AudioQueueStop method from this library before.

Background Audio in iOS

I'm trying to build an iOS App (iOS > 5.0). It should play music files when a timer, set by the user, ends. Here is my setup what if done so far:
I use avplayer
I've set Background Modes in my plist to "App plays Audio"
in my appDelegate I have:
NSError *sessionError = nil;
[[AVAudioSession sharedInstance] setDelegate:self];
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&sessionError];
before a song is going to be played a set:
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&sessionError];
[[AVAudioSession sharedInstance] setActive:YES error:&sessionError];
i notify my application on "playerItemDidPlayToEnd", stop the player and tell other apps like the music.app to become active again
_avPlayer = nil;
NSError *sessionError = nil;
[[AVAudioSession sharedInstance] setActive:NO withFlags:AVAudioSessionSetActiveFlags_NotifyOthersOnDeactivation error:&sessionError];
This works fine. You can have your music app playing in background. My App starts to play a song the music app fades away. My song is played and if its finished the music app continues to play. But only as long as my app isn't in background.
In background I get the error:
Error Domain=NSOSStatusErrorDomain Code=560161140 "The operation couldn\u2019t be completed. (OSStatus error 560161140.)"
Is it possible that both combinations of, playing in background (on custom events) and switching between f.e. music.app and my app in background isn't possible?
Here a the code of my player model: http://pastie.org/4830995
I think your problem might be with background handling. You need to override this function on app delegate.
- (void)applicationDidEnterBackground:(UIApplication *)application
{
__block UIBackgroundTaskIdentifier task = 0;
task=[application beginBackgroundTaskWithExpirationHandler:^{
NSLog(#"Expiration handler called %f",[application backgroundTimeRemaining]);
[application endBackgroundTask:task];
task=UIBackgroundTaskInvalid;
}];
}
your application will get killed after 6 minutes unless sound is played. If your user set timer for more then 6 minutes, what you could do is to play short quite sound every 5.5 minutes to keep you app alive and start new background task. Also you have to consider that lot of thing will not get executed in background. I did some stuff somewhat similar to what you are doing. What I did was created custom subclass of NSObject witch handled music playback and application expiration stuff. And made it a strong property on my delegate as lot of functions and notifications will not run on you VC in the background.
Although if you just want to play a sound this might not be the best approach. Maybe just sending local notification would do.
Hope this helped.
Did you register your app to keep running in the background as an audio app? To do so, add the UIBackgroundModes key to your Info.plist file and set its value to audio.

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