When my app launches, there are rumors that I can decide if any currently playing music is stopped or not.
My goal is to use Audio Queue Services, because I believe that's the most powerful audio technology in iPhone OS.
So, could I really decide that when my app launches? How? Which one of the many audio technologies on the iPhone OS is responsible for managing this?
See the class MPMusicPlayerController and the class method +iPodMusicPlayer
Related
I'm doing some audio streaming with iOS 7's Multipeer Connectivity framework. The streaming works well, but when I put the app on background it stops working.
Someone can tell me if this is a framework limitation, or I'm doing something wrong?
And, if it is a framework limitation, is it possible to do something to avoid this?
Can I use Background Tasks, to keep streaming and music working on background?
Is possible do this? If is not possible, do any alternatives exist for MultiPeer audio streaming between iOS devices?.
I´m using this example: https://github.com/tonyd256/TDAudioStreamer.
Explained on this page: http://robots.thoughtbot.com/streaming-audio-to-multiple-listeners-via-ios-multipeer-connectivity.
Thanks a lot!
On the Apple documentation for playing audio in the background (scroll down a bit). Some relevant paragraphs:
When the UIBackgroundModes key contains the audio value, the system’s media frameworks automatically prevent the corresponding app from being suspended when it moves to the background. As long as it is playing audio or video content or recording audio content, the app continues to run in the background. However, if recording or playback stops, the system suspends the app.
You can use any of the system audio frameworks to work with background audio content, and the process for using those frameworks is unchanged.
This means that iOS should recognize that you're playing audio through Core Audio, and keep your app unsuspended, as long as you've correctly configured your app for playing audio in the background.
Because your app is not suspended while playing media files, callbacks operate normally while your app is in the background. In your callbacks, though, you should do only the work necessary to provide data for playback. For example, a streaming audio app would need to download the music stream data from its server and push the current audio samples out for playback. Apps should not perform any extraneous tasks that are unrelated to playback.
You should be able to operate normally as long as your app is still playing audio, and is allowed to do what it needs to in order to continue playing audio. This means that you should be able to continue to use MPC in the background to receive the audio data and play it.
Be sure to read the entire documentation on the subject, especially regarding Audio Sessions.
iOS devices get limited cpu cycles for explicit purposes when they have been backgrounded by the user.
According to Apple's documentation on multitasking and execution in the background, the following types of apps are supported, but have to be explicitly declared:
Apps that play audible content to the user while in the background, such as a music player app
Apps that record audio content while in the background.
Apps that keep users informed of their location at all times, such as a navigation app
Apps that support Voice over Internet Protocol (VoIP)
Apps that need to download and process new content regularly
Apps that receive regular updates from external accessories
Your case falls under Apps that play audible content to the user while in the background, such as a music player app. You can find more information from the link provided above.
For example, if I start a song in Pandora and then open Safari to browse the web the Pandora song will keep playing. However, if I start a song in Pandora and then open my app it kills the Pandora song. How do I let Pandora keep playing while my app is running?
You need to tell the iOS system what behavior it should use to integrate the two audio sessions. By default it cancels the background audio when you use audio. But this behavior can be modified as described in the AVAudioSession docs here.
To quote:
Working with Music Players
To play audio from a user’s iPod library along with your own sounds
(as described in iPod Library Access Programming Guide), you must use
a so-called mixable category configuration for your audio session.
There are two, alternative ways to configure an audio session as
mixable:
Use the AVAudioSessionCategoryAmbient (or the equivalent
kAudioSessionCategory_AmbientSound) category—which is always mixable.
Use the mixable category override property
kAudioSessionProperty_OverrideCategoryMixWithOthers, as described in
“Fine-Tuning the Category,” to make an otherwise nonmixable playback
category mixable. Having used one of these options, your sounds will
not interrupt a music player—and neither will a music player’s sounds
interrupt yours.
There are two reasons why your app might "kill" the background app:
It starts to play music of its own
You use too much memory for it to keep playing and the OS closes the background app
There is no special option you need to select; you just need to be a "good citizen."
I'm an inexperienced XCode use and programmer in general so keep that in mind. I'm trying to use the microphone on the iPhone while at the same time allowing the user to play audio while using the "iPod music picker", but when the user selects music and plays it the recorder stops working? I have no idea what is going on here? Also, on a side note, how do you implement forward and back iPod buttons?
Thanks so much!
Sounds like this is an Audio Session issue - you're probably in a mode where you can either play or record, but not both at the same time.
Check out the Audio Session Programming Guide which should explain how to configure your session.
AVAudioSessionCategoryPlayAndRecord — Use this category for an application that inputs and outputs audio. The input and output need not occur simultaneously, but can if needed. This is the category to use for audio chat applications.
AVAudioSessionCategoryAmbient - This category allows audio from the iPod, Safari, and other built-in applications to play while your application is playing audio. You could, for example, use this category for an application that provides a virtual musical instrument that a user plays along to iPod audio.
I'm using SimpleAudioEngine to play my sounds and I was wondering if there is anyway to check if iPod music is playing when the app is launched. If so, I want it to continue playing. I'm starting to think it may be called the simple engine for a reason as it doesn't allow features like this, where AVAudioEngine does...
Thanks :)
You should check out the official Audio Session Programming Guide and make sure that you are setting the correct session category. You will want to pick the category that allows your audio to mix with the iPod audio.
I'm writing an iPhone app that uses OpenAL. When the application starts, the music playing in background stops.
The music actually stops playing when I initialize the OpenAL library.
My question is, is there any way to use OpenAL while letting the background music play?
You need to change the Audio Session Category to kAudioSessionCategory_AmbientSound instead of kAudioSessionCategory_SoloAmbientSound which is the default.
You can find out more about it in the Audio Session Programming Guide. Here's a link to the relevant part of the documentation.