ios - iOS相机脸部追踪(Swift 3 Xcode 8)

我正在尝试制作一个简单的摄像头应用程序，使前置摄像头可以检测到面部。
这应该足够简单:

创建一个从UIImage继承的CameraView类，并将其放置在UI中。确保它实现了AVCaptureVideoDataOutputSampleBufferDelegate以便实时处理摄像机中的帧。

class CameraView: UIImageView, AVCaptureVideoDataOutputSampleBufferDelegate

在实例化CameraView时调用的handleCamera函数中，设置AVCapture会话。添加来自摄像机的输入。

override init(frame: CGRect) {
    super.init(frame:frame)

    handleCamera()
}

func handleCamera () {
    camera = AVCaptureDevice.defaultDevice(withDeviceType: .builtInWideAngleCamera,
                                           mediaType: AVMediaTypeVideo, position: .front)
    session = AVCaptureSession()

    // Set recovered camera as an input device for the capture session
    do {
        try input = AVCaptureDeviceInput(device: camera);
    } catch _ as NSError {
        print ("ERROR: Front camera can't be used as input")
        input = nil
    }

    // Add the input from the camera to the capture session
    if (session?.canAddInput(input) == true) {
        session?.addInput(input)
    }

创建输出。创建一个串行输出队列，以将数据传递给AVCaptureVideoDataOutputSampleBufferDelegate(在本例中为类本身)处理。将输出添加到会话。

    output = AVCaptureVideoDataOutput()

    output?.alwaysDiscardsLateVideoFrames = true
    outputQueue = DispatchQueue(label: "outputQueue")
    output?.setSampleBufferDelegate(self, queue: outputQueue)

    // add front camera output to the session for use and modification
    if(session?.canAddOutput(output) == true){
        session?.addOutput(output)
    } // front camera can't be used as output, not working: handle error
    else {
        print("ERROR: Output not viable")
    }

设置摄像机预览视图并运行会话

    // Setup camera preview with the session input
    previewLayer = AVCaptureVideoPreviewLayer(session: session)
    previewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
    previewLayer?.connection.videoOrientation = AVCaptureVideoOrientation.portrait
    previewLayer?.frame = self.bounds
    self.layer.addSublayer(previewLayer!)

    // Process the camera and run it onto the preview
    session?.startRunning()

由委托运行的captureOutput函数中的

，将接收到的样本缓冲区转换为CIImage以便检测人脸。如果发现人脸，请提供反馈。

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

let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
let cameraImage = CIImage(cvPixelBuffer: pixelBuffer!)


let accuracy = [CIDetectorAccuracy: CIDetectorAccuracyHigh]
let faceDetector = CIDetector(ofType: CIDetectorTypeFace, context: nil, options: accuracy)
let faces = faceDetector?.features(in: cameraImage)

for face in faces as! [CIFaceFeature] {

      print("Found bounds are \(face.bounds)")

      let faceBox = UIView(frame: face.bounds)

      faceBox.layer.borderWidth = 3
      faceBox.layer.borderColor = UIColor.red.cgColor
      faceBox.backgroundColor = UIColor.clear
      self.addSubview(faceBox)

      if face.hasLeftEyePosition {
          print("Left eye bounds are \(face.leftEyePosition)")
      }

      if face.hasRightEyePosition {
          print("Right eye bounds are \(face.rightEyePosition)")
      }
  }
}

我的问题是:我可以使相机运行，但是由于我尝试了从互联网上进行的多种编码操作，因此我从未能够通过captureOutput检测到人脸。应用程序没有输入函数，或者由于变量不起作用而导致崩溃，通常是sampleBuffer变量为nul。
我究竟做错了什么？

最佳答案

您需要将captureOutput函数参数更改为以下内容:func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!)
您的captureOutput函数在缓冲区丢失时调用，而不是在从相机获取缓冲区时调用。

关于ios - iOS相机脸部追踪(Swift 3 Xcode 8)，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43389445/