ios - 设备相机数据(不是图像而是实际的相机属性)

Question

我需要访问我的设备相机数据(不是图像数据!已经有了)。例如，“针孔”fx 和 fy 以及我可能得到的任何其他东西。

目前，我正在使用带有自定义 UI 的 AVFoundation 的“AVCaptureSession”。但之前我使用了“UIImagePickerController”，它有一个名为

的委托(delegate)方法

imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any])

我能够从“信息”字典中检索到拍摄的照片。它还为我提供了有关相机及其功能的非常详细的信息。就目前而言，我不知道如何在“AVCaptureSession”摄影期间检索同样的详细信息。请帮忙

Answer 1

您需要使用 AVCapturePhotoOutput 而不是 AVCaptureStillImageOutput。

首先，下面的代码需要在您的类中添加以下变量

private let photoOutput = AVCapturePhotoOutput()
private var inProgressPhotoCaptureDelegates = [Int64 : AVPhotoCaptureDelegate]()
private let sessionQueue = DispatchQueue(label: "session queue", attributes: [], target: nil) // Communicate with the session     
private var videoDeviceOrientation : AVCaptureVideoOrientation = .portrait // this needs updated as the device orientation changes

在 AVSession 设置中添加照片输出

// Add photo output.
if session.canAddOutput(photoOutput) {
    session.addOutput(photoOutput)

    self.photoOutput.isHighResolutionCaptureEnabled = true
}

你的 capturePhoto() 函数应该设置如下

func capturePhoto(aspectRatio : Float, metaData : NSDictionary?) {
    sessionQueue.async {
        // Update the photo output's connection to match the video orientation of the video preview layer.
        if let photoOutputConnection = self.photoOutput.connection(with: AVMediaType.video) {
            photoOutputConnection.videoOrientation = self.videoDeviceOrientation
        }

        // Capture a JPEG photo with flash set to off and high resolution photo enabled.
        let photoSettings = AVCapturePhotoSettings()
        photoSettings.flashMode = .off
        photoSettings.isHighResolutionPhotoEnabled = true
        if photoSettings.availablePreviewPhotoPixelFormatTypes.count > 0 {
            photoSettings.previewPhotoFormat = [kCVPixelBufferPixelFormatTypeKey as String : photoSettings.availablePreviewPhotoPixelFormatTypes.first!]
        }

        // Use a separate object for the photo capture delegate to isolate each capture life cycle.
        let photoCaptureDelegate = MyAVPhotoCaptureDelegate(completed: { [unowned self] photoCaptureDelegate in
            // When the capture is complete, remove a reference to the photo capture delegate so it can be deallocated.
            self.sessionQueue.async { [unowned self] in
                self.inProgressPhotoCaptureDelegates[photoCaptureDelegate.requestedPhotoSettings.uniqueID] = nil
            }
        )

        /*
         The Photo Output keeps a weak reference to the photo capture delegate so
         we store it in an array to maintain a strong reference to this object
         until the capture is completed.
         */
        self.inProgressPhotoCaptureDelegates[photoCaptureDelegate.requestedPhotoSettings.uniqueID] = photoCaptureDelegate
        self.photoOutput.capturePhoto(with: photoSettings, delegate: photoCaptureDelegate)
    }
}

上面的 capturePhoto() 函数中引用的 MyAVPhotoCaptureDelegate 类需要按如下方式设置

class MyAVPhotoCaptureDelegate: NSObject, AVCapturePhotoCaptureDelegate {

    init(completed: @escaping (AVPhotoCaptureDelegate) -> ()) {
        self.completed = completed
    }

    private func didFinish() {
        completed(self)
    }

    func photoOutput(_ captureOutput: AVCapturePhotoOutput, willCapturePhotoFor resolvedSettings: AVCaptureResolvedPhotoSettings) {
    }

    func photoOutput(_ captureOutput: AVCapturePhotoOutput, didFinishProcessingPhoto photoSampleBuffer: CMSampleBuffer?, previewPhoto previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {
        if let photoSampleBuffer = photoSampleBuffer {
            let propertiesDictionary = NSMutableDictionary()

            if let exif = CMGetAttachment(photoSampleBuffer, kCGImagePropertyExifDictionary as NSString, nil) {
                if let exifDictionary = exif as? NSMutableDictionary {
                // view exif data
                }
            }

            photoData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: photoSampleBuffer, previewPhotoSampleBuffer: previewPhotoSampleBuffer)
        }
        else {
            print("Error capturing photo: \(String(describing:error))")
            return
        }
    }

    func photoOutput(_ captureOutput: AVCapturePhotoOutput, didFinishCaptureFor resolvedSettings: AVCaptureResolvedPhotoSettings, error: Error?) {

        // Use PHPhotoLibrary to save photoData to photo library
        ...
    }

    private let completed : (MyAVPhotoCaptureDelegate) -> ()
}

大部分代码来 self 的 AVCam 版本，删除了我的实现细节。我省略了保存到照片库的代码，但您可以从示例代码中提取它。你可以在我评论“查看exif数据”的地方查看exif数据