Fetracking iOS Camera (Swift 3 Xcode 8)

Question

I am trying to make a simple camera application where the front camera can detect faces. This should be simple enough:

• Create a CameraView class that inherits from UIImage and places it in the user interface. Make sure that it implements AVCaptureVideoDataOutputSampleBufferDelegate to process camera frames in real time.

  class CameraView: UIImageView, AVCaptureVideoDataOutputSampleBufferDelegate 
  

• Inside the handleCamera function that is called when the CameraView is instantiated, configure an AVCapture session. Add camera input.

  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)
      }
  

• Create a conclusion. Create a sequential output queue to pass data that will then be processed using AVCaptureVideoDataOutputSampleBufferDelegate (in this case the class itself). Add output to the session.

      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")
      }
  

•     // 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()
  

• captureOutput, , CIImage . , .

  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)")
        }
    }
  }
  

: , , , captureOutput, . , - , , , sampleBuffer nul. ?

Answer 1

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

captureOutput , .