I have an App that does the pretty standard operation:
It plays audio (streamed or in filesystem) when the app is in 1) Foreground mode, 2) Screen locked state 3)Background mode.
This was working fine in all iOS prior to iOS5.
I have been using MPMoviePlayerController (Because it can play streamed and local file system audio)
I have the following setup:
info.plist has Background Mode set to "Audio"
I have Audiosession setup as shown at http://developer.apple.com/library/ios/#qa/qa1668/_index.html
NSError *activationError = nil;
AVAudioSession *mySession = [AVAudioSession sharedInstance];
[mySession setCategory: AVAudioSessionCategoryPlayback error: &activationError];
if (activationError) { /* handle the error condition */ }
[mySession setActive: YES error: &activationError];
if (activationError) { /* handle the error condition */ }
I have background timer enabled that gets stopped at the end of audio playback
UIBackgroundTaskIdentifier newId = [[UIApplication sharedApplication]
beginBackgroundTaskWithExpirationHandler:NULL];
I have the Moveplayer's useApplicationAudioSession = NO
I have subscribed to the following events to detect and handle various playback state and to start a new audio file at the end of current file.
MPMoviePlayerLoadStateDidChangeNotification
MPMoviePlayerPlaybackDidFinishNotification
MPMoviePlayerPlaybackStateDidChangeNotification
MPMoviePlayerNowPlayingMovieDidChangeNotification
Problem:
With this the audio starts to play and when the application is put to background state or if the phone is locked, the audio continues to play. But, after when I start another audio file,
I start getting PlaybackDidFinishNotification immediately with the state set to Playback ended (But the file was never played)
The same code plays audio files in foreground mode (After the current audio file ends, the next file is started without any problem)
Is there anything new in iOS5 I should be doing to get this to work? I read through the MPMoviePlayerController class reference and I couldn't see anything specific for iOS5.
Thanks in advance.
Finally figured out the issue. This is solved in this post in apple dev forums (needs login to see). That post was applicable to AVPlayer but also fixes the problem with MPMoviePlayerController as well.
Basically, this is an excerpt from that post:
your app must support remote control events! These are the audio
controller interface prex/nex/play/pause on the left of the multitask
switcher taskbar (not sure about the proper name of the thing). You
to this ensuring your view becomes First Controller and then calling
> [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
in viewDidLoad. Once you do this, your Player will no longer return
NO!!
My situation was different and I'm only answering here (and in the other SO question) to help future searchers on this error message. This does not answer the original question.
My app plays a sound OR a song but when I first coded it could play both. And in testing I always tested with a song. I played the song in the usual way:
self.musicQuery = [MPMediaQuery songsQuery];
[_musicQuery addFilterPredicate:[MPMediaPropertyPredicate predicateWithValue:selectedSongID forProperty:MPMediaItemPropertyPersistentID comparisonType:MPMediaPredicateComparisonEqualTo]];
[_musicQuery setGroupingType:MPMediaGroupingTitle];
[_myPlayer setQueueWithQuery:_musicQuery];
[_myPlayer play];
Weeks passed and I started testing with the sound, played with AVAudioPlayer. My app started freezing for 5 seconds and I'd get the MediaPlayer: Message playbackState timed out message in the Console.
It turns out that passing a query that was empty was causing the freeze and the message. Changing my app's logic to only play a song when there was a song to play fixed it.
Related
Apple resources contain a lot of informations but there's one thing which I can't clearly understand reading about audio and notification.
Is it possible to make an app, running in background which produce sound (even if phone is locked and/or silenced) and when it's happend user must solve eg. equation to turn it off?
p.s. For now I mostly use Cordova framework but Obj-C tip will also be nice.
Yes it is posssible.
You can use UILocalNotification for this.
Also apple allows apps that are playing music in background.
Please check these links for the background task feature:
ManagingYourApplicationsFlow
ios multitasking background tasks
How to handle background audio playing while ios device is locked or on another
You can change Local Notifications for NSTimers (keeping them alive in inactive mode with https://github.com/mruegenberg/MMPDeepSleepPreventer) and calculate the time interval for each alarm. That way you can then play an audio even with the screen locked and the sound off pasting this in your - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions:
// Let the sound run with the screen blocked
NSError *setCategoryErr = nil;
NSError *activationErr = nil;
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error:&setCategoryErr];
[[AVAudioSession sharedInstance] setActive:YES error:&activationErr];
But you will have some problems:
The app must be playing an audio file each 10 seconds so it doesn´t deep sleep and kills all NSTimers.
Apple could reject your app for doing so.
You can´t close the app with the home button, otherwise, it won´t work.
You must open the app every time you need to use the alarm (you can´t schedule and forget).
When the alarm fires, you only have the lock screen of the iPhone and need to unlock it first and then stop the alarm from inside the app.
In Apple they don´t want competitors for their alarm clock app, that's for sure! Almost all the alarm clock apps you see in the App Store use this poor approach.
I have a codebase which plays audio and video perfectly. I have converted that into a small framework and started using it as a part of another code. When i do this, there is no audio output.... I am unable to hear any audio output while it is being played. All the Audio player delegate methods are being called but there is no sound. The same is happening with Videos as well. All the videos are being played with out sound. Its like watching a silent movie.... Any ideas? I am using AVAudioPlayer for playing audio files and MPMoviePlayerController for playing videos.
edit : This happens only on device. It works all fine in simulator
Just came across this post, I was doing the same thing, and actually AVAduioSession is needed to play audio thru speaker/headset. So having AVAudioSession is a must.
//REALLY NEED THIS LINE FOR MUSIC TO PLAY TO SPEAKER
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
and for background playing, add these 2 lines and change setting in plist to allow background mode
[[AVAudioSession sharedInstance] setActive: YES error: nil];
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
So stupid of me.... The problem was with the volume button on iPad. The volume button in iPad with iOS 5 has some weird bug. It does not update itself when we toggle the button between screen lock and audio output. I guess this is bug from apple and filed a bug. Hope they solve this in their next update.
I am using MPMoviePlayerController to play streaming audio. I'm trying to get background audio working correctly. Right now, audio continues to play when you exit the app - the lock-screen and multi-tasking bar controls even work.
When a song finishes, the app is supposed to advance to the next track and play it. It works when the app is open but not when it is in the background (a song finishes but does not advance to the next track). If a song finishes and you re-open the app, however, the next song will start up immediately.
I am currently using NSNotificationCenter to keep track of when tracks end to advance to the next track (in my app delegate). Again, it works like a charm when the app is open. Is there a better way to do this to keep audio playing after a song is done?
I had this issue lately. Hope the answer helps other people.
If you have a playlist for example and want to play the next song while in background mode or lock mode add this line of code on your viewDidLoad:
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
This makes the app supports remote control events.
We have a volume slider on the audio player in our iphone app. It streams music from our server. All is well initially until the point that some background operation happens on the iPhone.
Eg: The Mail app downloads new mails in the background and that makes a little audio sound
or
I receive a new SMS and that gives a little sound alert.
In such cases, the volume of our music player increases or decreases abruptly. The slider stays where it is, but the volume pitch changes. The only way to get where it was before is pause and play again and then the volume re-adjusts.
Any idea how to solve this issue?
Thank you in advance
Swap
Sounds like a classic Audio Session Category issue.
Check the Audio Session Programming Guide on Configuring your Audio Session.
Specifically, try to setup your application audio session towards AVAudioSessionCategoryPlayback.
NSError *setCategoryError = nil;
[[AVAudioSession sharedInstance]
setCategory: AVAudioSessionCategoryPlayback
error: &setCategoryError];
if (setCategoryError) { /* handle the error condition */ }
My app uses NSTimer and it appears that NSTimer doesn't fire when the iPhone goes into the stand-by mode (either by pressing the hardware button or by the idle timer).
When I activate the iPhone again, my app is still in the foreground. What happens to third party apps when the iPhone is the stand-by mode?
Although it's not evident here, I believe the original poster did find an answer to his question by starting a thread (available here) in the iPhone Developer Forums (which I eventually had to find myself because the information wasn't shared here).
In case someone else has the same question and finds the page in the future, here's a helpful response that was posted by someone on the Apple forum called "eskimo1" (which I have edited slightly such that it is easier to read without having the context provided by the entire original thread):
Regarding iPhone app status terminology, "active" does not mean "awake", it means "attached to the GUI". Think of it being analogous to "frontmost" in Mac OS X. When you lock the device your app deactivates but the device may or may not go to sleep
iPhone OS rarely sleeps if the device is connected to main power (i.e., via USB). It can sleep if running on battery, however.
A short time after the screen is locked (20 seconds according to Oliver Drobnik), the device sleeps. This is like closing the lid on your laptop; all activity on the main CPU halts.
This does not happen if the device is playing audio in the right audio session. See DTS Q&A QA1626 "Audio Session - Ensuring audio playback continues when screen is locked" for details.
Note that the idleTimerDisabled property (which can be turned on to prevent the screen from turning off while the app is running) is about locking the screen after user inactivity. It's not directly related to system sleep (it's indirectly related in that the system may sleep shortly after it's locked).
See Application Interruptions in the iPhone OS Programming Guide, especially the applicationWillResignActive and applicationDidBecomeActive events. (The whole guide is certainly worth reading.) When You ignore the events, the timer seems to go on for a while and then stops. Sounds logical, the application could easily drain the battery if kept running. And what exactly happens to the application? I guess it simply does not get any CPU time – it freezes and only thaws when You turn the machine back “on.”
My first advice is do not disable the idle timer, that is just a hack. If you want to keep a timer alive during UI events run the timer on the current run loop using NSCommonModes:
// create timer and add it to the current run loop using common modes
self.timer = [NSTimer timerWithTimeInterval:.1 target:self selector:#selector(handleTimer) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
I used the information on this post for a small sample that I was building. This is the code that I used when I initiated the playback to prevent the audio from stopping:
AudioSession.Category = AudioSessionCategory.MediaPlayback;
And when the application is done with the playback to reset to the original value:
AudioSession.Category = AudioSessionCategory.SoloAmbientSound;
The full sample is here:
http://github.com/migueldeicaza/monotouch-samples/tree/master/StreamingAudio/
I was faced with this issue recently in an app I am working on that uses several timers and plays some audio prompts and made two relatively simple changes:
In the AppDelegate I implemented the following methods and there mere presence allows the app to continue when the screen is locked
// this receives the notification when the device is locked
- (void)applicationWillResignActive:(UIApplication *)application
{
}
// this receives the notification that the application is about to become active again
- (void)applicationWillBecomeActive:(NSNotification *)aNotification
{
}
references: UIApplicationDelegate Protocol Reference & NSApplication Class Reference in the API doc (accessible via Xcode, just search for applicationWillBecomeActive).
Made the main viewcontroller class an AVAudioPlayerDelegate and used this code from Apple's "AddMusic" sample to make the audio alerts the app played mix nicely into the iPod audio etc...
I just dropped this code into a method that is called during viewDidLoad. If this interests you, you fall into the "who should read this doc" category for this: Audio Session Programming Guide
// Registers this class as the delegate of the audio session.
[[AVAudioSession sharedInstance] setDelegate: self];
// The AmbientSound category allows application audio to mix with Media Player
// audio. The category also indicates that application audio should stop playing
// if the Ring/Siilent switch is set to "silent" or the screen locks.
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryAmbient error: nil];
// Activates the audio session.
NSError *activationError = nil;
[[AVAudioSession sharedInstance] setActive: YES error: &activationError];
I believe your application should run normally when suspended. (think Pandora Radio)
Check to see if your timer is being deallocated due to your view being hidden or some other event occurring.