音频将使AVCaptureSession终止

Question

我写了一个应用程序来录制来自iPhone的视频。它工作得很好，但有一个大问题。当AVCaptureSession开始运行时，用户尝试播放他们库(IPod)中的音频。此操作将使AVCaptureSession终止。有什么想法可以防止用户尝试播放音频或解决这个问题吗？

这是我的密码：

videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];           
audioDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];

AVCaptureDeviceInput *videoDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:videoDevice error:nil];
AVCaptureDeviceInput *audioDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:audioDevice error:nil];

movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];

captureSession = [[AVCaptureSession alloc] init];

[captureSession beginConfiguration];
[captureSession setSessionPreset:AVCaptureSessionPresetHigh];
[captureSession addInput:videoDeviceInput];
[captureSession addInput:audioDeviceInput];
[captureSession addOutput:movieFileOutput];
[captureSession commitConfiguration];

[captureSession startRunning];

Answer 1

这对我起了作用：

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

}

Answer 2

您需要使用NSNotificationCenter。使用下面的代码(我还包括一些其他有用的方法)，并为AVCaptureSessionWasInterruptedNotification编写一个方法，它将以任何方式处理捕获中断。我希望这能帮上忙。

NSNotificationCenter *notify = [NSNotificationCenter defaultCenter];
[notify addObserver: self selector: @selector(onVideoError:) name: AVCaptureSessionRuntimeErrorNotification object: captureSession];
[notify addObserver: self selector: @selector(onVideoInterrupted:) name: AVCaptureSessionWasInterruptedNotification object: captureSession];
[notify addObserver: self selector: @selector(onVideoEnded:) name: AVCaptureSessionInterruptionEndedNotification object: captureSession];
[notify addObserver: self selector: @selector(onVideoDidStopRunning:) name: AVCaptureSessionDidStopRunningNotification object: captureSession];
[notify addObserver: self selector: @selector(onVideoStart:) name: AVCaptureSessionDidStartRunningNotification object: captureSession];

Answer 3

尝试干扰音频会话！

下面是关于您可以做什么的快速猜测，但是我还没有在iPod中具体地尝试过这一点：

OSStatus status = noErr;
status |= AudioSessionInitialize(CFRunLoopGetMain(), kCFRunLoopCommonModes, PVAudioSessionInterruptionListener, NULL);

    status |= AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(UInt32), &(UInt32){kAudioSessionCategory_PlayAndRecord});

    status |= AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryMixWithOthers,
                                      sizeof(UInt32),
                                      &(UInt32){true});

    status |= AudioSessionSetProperty(kAudioSessionProperty_OtherMixableAudioShouldDuck,
                                      sizeof(UInt32),
                                      &(UInt32){false});

status |= AudioSessionSetActive(YES);

if (status != noErr) {
    NSLog(@"ERROR: There was an error in setting the audio session");
}

我还对环境音频类别有了一些运气(尽管它给出了一个错误，它似乎允许在录制视频时播放音频)：

    status |= AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(UInt32), &(UInt32){kAudioSessionCategory_AmbientSound});