captureOutput:didOutputSampleBuffer:from 连接中的方向问题：

Question

我正在尝试处理 AVCaptureSession 的每一帧并在 UIImageView 中预览过滤后的图像。它可以工作，但 UIImageView 中的图像出现旋转（并且扭曲）。我一直试图在这里和谷歌中寻找答案，但我找不到任何有效的解决方案...有人知道要尝试什么吗？

顺便说一句，我正在使用 Swift 3.0

这是我正在使用的代码：

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {

    let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    let attachments = CMCopyDictionaryOfAttachments(kCFAllocatorMalloc, sampleBuffer!, kCMAttachmentMode_ShouldPropagate)
    let coreImage = CIImage(cvImageBuffer: pixelBuffer!, options: attachments as! [String : Any]?)
    var filteredImage = UIImage(ciImage: coreImage, scale: 1.0, orientation: UIImageOrientation.right)

    if filter {
        NSLog("FILTER ACTIVATED")
        let filterType = CIFilter(name: "CISepiaTone")
        filterType?.setValue(coreImage, forKey: kCIInputImageKey)
        filterType?.setValue(0.5, forKey: kCIInputIntensityKey)
        filteredImage = UIImage(ciImage: filterType!.value(forKey: kCIOutputImageKey) as! CIImage!, scale: filteredImage.scale, orientation: UIImageOrientation.right)
    }

    DispatchQueue.main.async() {
        self.imageViewPreview.image = filteredImage // UIImageView
    }
}

这就是我在预览中看到的：

UIImageView预览

提前非常感谢

Answer 1

我找到了！事实证明我必须在该方法中添加行

connection.videoOrientation = AVCaptureVideoOrientation.portrait

...

Answer 2

对于 iOS 17+：

创建一个rotationCoordinator变量：

private var rotationCoordinator: AVCaptureDevice.RotationCoordinator?

在

configurePreviewLayer()

中分配旋转协调器：

func configurePreviewLayer(_ view: UIView) {
    guard let videoDevice = AVCaptureDevice.default(.builtInWideAngleCamera,
                                                    for: .video,
                                                    position: .back) else { return }
        
    previewLayer = AVCaptureVideoPreviewLayer(session: session)
    previewLayer?.videoGravity = .resizeAspectFill
        
    guard let previewLayer = previewLayer else { return }
    view.layer.addSublayer(previewLayer)
        
    rotationCoordinator = AVCaptureDevice.RotationCoordinator(device: videoDevice, previewLayer: previewLayer)
}

然后用它来将

videoRotationAngle

分配给

connection

中的

captureOutput()

：

func captureOutput(_ output: AVCaptureOutput,
                      didOutput sampleBuffer: CMSampleBuffer,
                      from connection: AVCaptureConnection) {
    guard let coordinator = rotationCoordinator else { return }
    connection.videoRotationAngle = coordinator.videoRotationAngleForHorizonLevelCapture
        
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }
        
    let ciImage = CIImage(cvImageBuffer: imageBuffer)
    let context = CIContext()
    guard let cgImage = context.createCGImage(ciImage, from: ciImage.extent) else { return }
        
    currentFrame = UIImage(cgImage: cgImage)
}

注意使用

videoRotationAngleForHorizonLevelCapture

而不是

videoRotationAngleForHorizonLevelPreview

。