Question

I have an app that plays some background music, when a certain button is pushed, it pushes a new view using the navigation controller. That new view has a MPMoviePlayerController and an AVCaptureSession with a shared AudioSession. After that view is dismissed, the sound in the background is really soft compared to how it was. What is it that is causing the volume to be so subdued after playing?

NSError* error4 = nil;
AVAudioSession* audioSession = [AVAudioSession sharedInstance];
if (![audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:&error4]) {
    NSLog(@"AVAudioSession setCategory failed: %@", [error4 localizedDescription]);
}

// Set audio session property "allow mixing" to true so audio can be recorded while it is playing
UInt32 allowMixing = true;
OSStatus status = AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryMixWithOthers, sizeof(allowMixing), &allowMixing);
if (status != kAudioSessionNoError) {
    NSLog(@"AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryMixWithOthers) failed: %ld", status);
}

// Activate the audio session
error4 = nil;
if (![audioSession setActive:YES error:&error4]) {
    NSLog(@"AVAudioSession setActive:YES failed: %@", [error4 localizedDescription]);
}
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [paths objectAtIndex:0];

NSString *proud = [[documentsDirectoryPath stringByAppendingPathComponent:@"imissyou"] stringByAppendingPathComponent:selectedCountry];

NSURL  *movieURL = [[NSURL fileURLWithPath:proud] retain];
player =

[[MPMoviePlayerController alloc] initWithContentURL: movieURL];
player.useApplicationAudioSession=YES;

[player prepareToPlay];
player.controlStyle = MPMovieControlStyleNone;
player.allowsAirPlay = NO;
player.scalingMode = MPMovieScalingModeFill;   

player.view.frame = self.view.frame;

[self.view insertSubview:player.view belowSubview:vImagePreview];

[player setFullscreen:YES animated:YES];

// ...

[[NSNotificationCenter defaultCenter] 
 addObserver:self
 selector:@selector(movieFinishedCallback:)
 name:MPMoviePlayerPlaybackDidFinishNotification
 object:player];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(exitedFullscreen:) name:MPMoviePlayerDidExitFullscreenNotification object:player];


[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(moviePlayerWillExitFullscreen:)
                                             name:MPMoviePlayerWillExitFullscreenNotification
                                           object:player];


[player play];


session = [[AVCaptureSession alloc] init];
[session beginConfiguration];
session.sessionPreset = AVCaptureSessionPresetMedium;

CALayer *viewLayer = self.vImagePreview.layer;
NSLog(@"viewLayer = %@", viewLayer);

AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
captureVideoPreviewLayer.frame = self.vImagePreview.bounds;
[captureVideoPreviewLayer setCornerRadius:14];
[captureVideoPreviewLayer setBorderWidth:3.0];
[captureVideoPreviewLayer setBorderColor:[[UIColor whiteColor] CGColor]];
[[vImagePreview layer] setCornerRadius:14];


[[vImagePreview layer] setBorderWidth:3.0];


[[vImagePreview layer] setBorderColor:[[UIColor whiteColor] CGColor]];

[self.vImagePreview.layer addSublayer:captureVideoPreviewLayer];
[captureVideoPreviewLayer release];
AVCaptureDevice *device = [self frontFacingCameraIfAvailable];
NSError *error = nil;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input) {
    // Handle the error appropriately.
    NSLog(@"ERROR: trying to open camera: %@", error);
}

AVCaptureDevice *audioCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
NSError *error2 = nil;
AVCaptureDeviceInput *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioCaptureDevice error:&error2];






AVCaptureMovieFileOutput *movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];

NSString *archives = [documentsDirectoryPath stringByAppendingPathComponent:@"archives"];
NSString *editedfilename = [[selectedCountry lastPathComponent] stringByDeletingPathExtension];
NSString *datestring = [[editedfilename stringByAppendingString:@" "] stringByAppendingString:currentTime];
NSLog(@"%@", datestring);
NSString *outputpathofmovie = [[archives stringByAppendingPathComponent:datestring] stringByAppendingString:@".mp4"];
NSURL *outputURL = [[NSURL alloc] initFileURLWithPath:outputpathofmovie];
[session addInput:input];
[session addInput:audioInput];
[session addOutput:movieFileOutput];
[session commitConfiguration];
[session startRunning];
[movieFileOutput startRecordingToOutputFileURL:outputURL recordingDelegate:self];
[movieURL release];
[outputURL release];

Answer 1

I got it figured out now. I had category set to PlayAndRecord. I changed it to Ambient (which also allows to record audio while playing audio) and removed property of OverrideCategoryMixWithOthers, leaving just

OSStatus propertySetError = 0; 
UInt32 allowMixing = true; 
propertySetError |= AudioSessionSetProperty(kAudioSessionProperty_OtherMixableAudioShouldDuck, sizeof(allowMixing), &allowMixing);