无法从iPhone X上的双摄像头拍摄双张照片

Question

我试图同时从iPhoneX上的远摄和广角相机捕捉。这是我初始化设备的方式：

let captureDevice = AVCaptureDevice.default(.builtInDualCamera, for: .video, position: .back)

我要求为AVPhotoOutput提供双张照片：

let photoSettings = AVCapturePhotoSettings()

photoSettings.isDualCameraDualPhotoDeliveryEnabled = true

capturePhotoOutput.capturePhoto(with: photoSettings, delegate: self)

但是，我遇到了这个错误：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[AVCapturePhotoOutput setDualCameraDualPhotoDeliveryEnabled:] Dual Camera dual photo delivery is not supported in this configuration'

我需要启用或禁用其他设置吗？

Answer 1

您必须确保正确配置了捕获设备，捕获会话和捕获输出：

1. 使用以下设置（在您的代码中已经正确）获取捕获设备：AVCaptureDeviceTypeBuiltInDualCamera，AVMediaTypeVideo，AVCaptureDevicePositionBack

2. 使用您刚刚在1中检索到的设备创建AVCaptureDeviceInput。

3. 创建AVCaptureSession并将其sessionPreset设置为AVCaptureSessionPresetPhoto
4. 创建AVCapturePhotoOutput
5. 将创建的AVCaptureDeviceInput和AVCapturePhotoOutput添加到AVCaptureSession
6. 将AVCapturePhotoOutput的dualCameraDualPhotoDeliveryEnabled设置为YES
7. 开始捕获会话

对应的代码（目标C）：

// Create capture device discovery session to retrieve devices matching our
// needs
// -------------------------------------------------------------------------------
AVCaptureDeviceDiscoverySession*    captureDeviceDiscoverySession = [AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInDualCamera]
                                                                                                                           mediaType:AVMediaTypeVideo
                                                                                                                            position:AVCaptureDevicePositionBack];

// Loop through the retrieved devices and select correct one
// -------------------------------------------------------------------------------
for(AVCaptureDevice* device in [captureDeviceDiscoverySession devices])
{
    if(device.position == AVCaptureDevicePositionBack)
    {
        self.captureDevice = device;
        break;
    }
}

// Get camera input
// -------------------------------------------------------------------------------
NSError*                error               = nil;
AVCaptureDeviceInput*   videoDeviceInput    = [AVCaptureDeviceInput deviceInputWithDevice:self.captureDevice error:&error];

if(!videoDeviceInput)
{
    NSLog(@"Could not retrieve camera input, error: %@", error);
    return;
}

// Initialize capture session
// -------------------------------------------------------------------------------   
self.captureSession                 = [[AVCaptureSession alloc] init];
self.captureSession.sessionPreset   = AVCaptureSessionPresetPhoto;

// Add video device input and photo data output to our capture session
// -------------------------------------------------------------------------------
self.captureOutput  = [AVCapturePhotoOutput new];
[self.captureSession beginConfiguration];
if(![self.captureSession canAddOutput:self.captureOutput])
{
    NSLog(@"Cannot add photo output!");
    return;
}

[self.captureSession addInput:videoDeviceInput];
[self.captureSession addOutput:self.captureOutput];
[self.captureSession commitConfiguration];

// Configure output settings AFTER input & output have been added to the session
// -------------------------------------------------------------------------------
if(self.captureOutput.isDualCameraDualPhotoDeliverySupported)
    self.captureOutput.dualCameraDualPhotoDeliveryEnabled = YES;

// Create video preview layer for this session, and add it to our preview UIView
// -------------------------------------------------------------------------------
AVCaptureVideoPreviewLayer* videoPreviewLayer   = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
videoPreviewLayer.videoGravity                  = AVLayerVideoGravityResizeAspect;
videoPreviewLayer.frame                         = self.view.bounds;
[self.view.layer addSublayer:videoPreviewLayer];

// Start capturing session
// -------------------------------------------------------------------------------
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
    [self.captureSession startRunning];
});

1. 以后，对于要从AVCapturePhotoOutput请求的每张照片，请使用dualCaperaDualPhotoDeliveryEnabled设置为YES的AVCapturePhotoSettings

代码（目标C）：

AVCapturePhotoSettings* settings = [AVCapturePhotoSettings photoSettingsWithFormat:@{AVVideoCodecKey: AVVideoCodecTypeJPEG}];
settings.dualCameraDualPhotoDeliveryEnabled = YES;
[self.captureOutput capturePhotoWithSettings:settings delegate:self];