Ich habe die Aufgabe einer Universität, visuelle Effekte zu erzielen und diese auf Videobilder anzuwenden, die mit der Kamera des Geräts aufgenommen wurden. Ich kann derzeit das Bild und die Anzeige abrufen, aber die Pixelfarbwerte nicht ändern.

Ich transformiere den Sample-Buffer in die Variable imageRef und wenn ich ihn in UIImage transformiere, ist alles in Ordnung.

Aber jetzt möchte ich mit imageRef Pixel für Pixel die Werte seiner Farbe ändern. In diesem Beispiel werden negative Farben angezeigt (ich muss kompliziertere Dinge tun, damit ich keine CIFilter verwenden kann), aber wenn ich den kommentierten Teil ausführe, stürzt er ab wegen schlechtem zugang.

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCaptureVideoDataOutputSampleBufferDelegate {

  let captureSession = AVCaptureSession()
  var previewLayer : AVCaptureVideoPreviewLayer?

  var captureDevice : AVCaptureDevice?

  @IBOutlet weak var cameraView: UIImageView!

  override func viewDidLoad() {
    super.viewDidLoad()

    captureSession.sessionPreset = AVCaptureSessionPresetMedium

    let devices = AVCaptureDevice.devices()

    for device in devices {
      if device.hasMediaType(AVMediaTypeVideo) && device.position == AVCaptureDevicePosition.Back {
        if let device = device as? AVCaptureDevice {
          captureDevice = device
          beginSession()
          break
        }
      }
    }
  }

  func focusTo(value : Float) {
    if let device = captureDevice {
      if(device.lockForConfiguration(nil)) {
        device.setFocusModeLockedWithLensPosition(value) {
          (time) in
        }
        device.unlockForConfiguration()
      }
    }
  }

  override func touchesBegan(touches: NSSet!, withEvent event: UIEvent!) {
    var touchPercent = Float(touches.anyObject().locationInView(view).x / 320)
    focusTo(touchPercent)
  }

  override func touchesMoved(touches: NSSet!, withEvent event: UIEvent!) {
    var touchPercent = Float(touches.anyObject().locationInView(view).x / 320)
    focusTo(touchPercent)
  }

  func beginSession() {
    configureDevice()

    var error : NSError?
    captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: &error))

    if error != nil {
      println("error: \(error?.localizedDescription)")
    }

    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)

    previewLayer?.frame = view.layer.frame
    //view.layer.addSublayer(previewLayer)

    let output = AVCaptureVideoDataOutput()
    let cameraQueue = dispatch_queue_create("cameraQueue", DISPATCH_QUEUE_SERIAL)
    output.setSampleBufferDelegate(self, queue: cameraQueue)
    output.videoSettings = [kCVPixelBufferPixelFormatTypeKey: kCVPixelFormatType_32BGRA]

    captureSession.addOutput(output)
    captureSession.startRunning()
  }

  func configureDevice() {
    if let device = captureDevice {
      device.lockForConfiguration(nil)
      device.focusMode = .Locked
      device.unlockForConfiguration()
    }
  }

  // MARK : - AVCaptureVideoDataOutputSampleBufferDelegate

  func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {
    let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
    CVPixelBufferLockBaseAddress(imageBuffer, 0)

    let baseAddress = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0)
    let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer)
    let width = CVPixelBufferGetWidth(imageBuffer)
    let height = CVPixelBufferGetHeight(imageBuffer)
    let colorSpace = CGColorSpaceCreateDeviceRGB()

    var bitmapInfo = CGBitmapInfo.fromRaw(CGImageAlphaInfo.PremultipliedFirst.toRaw())! | CGBitmapInfo.ByteOrder32Little

    let context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, bitmapInfo)
    let imageRef = CGBitmapContextCreateImage(context)

    CVPixelBufferUnlockBaseAddress(imageBuffer, 0)

    let data = CGDataProviderCopyData(CGImageGetDataProvider(imageRef)) as NSData
    let pixels = data.bytes

    var newPixels = UnsafeMutablePointer<UInt8>()

    //for index in stride(from: 0, to: data.length, by: 4) {

      /*newPixels[index] = 255 - pixels[index]
      newPixels[index + 1] = 255 - pixels[index + 1]
      newPixels[index + 2] = 255 - pixels[index + 2]
      newPixels[index + 3] = 255 - pixels[index + 3]*/
    //}

    bitmapInfo = CGImageGetBitmapInfo(imageRef)
    let provider = CGDataProviderCreateWithData(nil, newPixels, UInt(data.length), nil)

    let newImageRef = CGImageCreate(width, height, CGImageGetBitsPerComponent(imageRef), CGImageGetBitsPerPixel(imageRef), bytesPerRow, colorSpace, bitmapInfo, provider, nil, false, kCGRenderingIntentDefault)

    let image = UIImage(CGImage: newImageRef, scale: 1, orientation: .Right)
    dispatch_async(dispatch_get_main_queue()) {
      self.cameraView.image = image
    }
  }
}