AVCaptureSession and background audio iOS 7

问题

Whenever I start an AVCaptureSession running with the microphone as an input it cancels whatever background music is currently running (iPod music for instance). If I comment out the line adding the audio input, the background audio continues.

Does anyone know a way to record video clips with the microphone while continuing to allow background audio to play? Also there is error, when you trying to record video and the music is currently playing.

A tried to do like this:

[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error: nil];
UInt32 doSetProperty = 1;
AudioSessionSetProperty (kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(doSetProperty), &doSetProperty);
[[AVAudioSession sharedInstance] setActive: YES error: nil];

But \'AudioSessionSetProperty\' is deprecated: first deprecated in iOS 7.0

So I tried to do like this:

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *setCategoryError = nil; 
[audioSession setCategory:AVAudioSessionCategoryPlayback
              withOptions:AVAudioSessionCategoryOptionMixWithOthers
                    error:&setCategoryError];
[audioSession setActive:YES error:nil];

But finally it didn\'t work. Thanks for help!

回答1:

You can use the AVAudioSessionCategoryOptionMixWithOthers. For instance,

AVAudioSession *session = [AVAudioSession sharedInstance];
[session setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionMixWithOthers error:nil];

After that, you can use the AVAudioPlayer simultaneously with AVCaptureSession.

However, the above code leads to very low volume. If you want normal volume, use the AVAudioSessionCategoryOptionDefaultToSpeaker with AVAudioSessionCategoryOptionMixWithOthers as follows,

[session setCategory:AVAudioSessionCategoryPlayAndRecord  withOptions:AVAudioSessionCategoryOptionMixWithOthers|AVAudioSessionCategoryOptionDefaultToSpeaker error:nil];

This goes well.

回答2:

In your AppDelegate:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //Stop app pausing other sound.
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord
                                     withOptions:AVAudioSessionCategoryOptionDuckOthers | AVAudioSessionCategoryOptionDefaultToSpeaker
                                           error:nil];
}

Where you are allocating AVCaptureSession:

AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.automaticallyConfiguresApplicationAudioSession = NO;

This code will allow you to play background music and run AVCaptureSession with the microphone.

SWIFT UPDATE:

AppDelegate:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    //Stop app pausing other sound.
    do{
        try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayAndRecord, 
                                            withOptions: [.DuckOthers, .DefaultToSpeaker])
    }
    catch {

    }

    return true
}

Where you are allocating AVCaptureSession:

let session = AVCaptureSession()
session.automaticallyConfiguresApplicationAudioSession = false

来源：https://stackoverflow.com/questions/21869802/avcapturesession-and-background-audio-ios-7

标签

ios

objective-c

avcapturesession

avaudiosession

avcapturedevice