AVFoundation: Take High Quality Still Image in Video-Session - objective-c

Question

I am anlysing live-images in a Capture-Session of Type AVMediaTypeVideo. How can I capture a high-quality-still image (not the low-resolution sample buffer), at certain events=
var videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
var device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
var previewLayer: AVCaptureVideoPreviewLayer?
var captureSession = AVCaptureSession()
let cameraOutput = AVCapturePhotoOutput()
//called in view did load
private func setupCamera() {
let input = try? AVCaptureDeviceInput(device: videoCaptureDevice)
captureSession.sessionPreset = AVCaptureSessionPreset640x480
if self.captureSession.canAddInput(input) {
self.captureSession.addInput(input)
}
self.previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
let videoDataOutput = AVCaptureVideoDataOutput()
if self.captureSession.canAddOutput(videoDataOutput){
self.captureSession.addOutput(videoDataOutput)
videoDataOutput.setSampleBufferDelegate(self, queue: DispatchQueue.main)
}
}
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
// sampleBuffer is analysed
// if result is positive, I would like to take a high quality picture
}

Answer 1

Here's a little snippet that I use in my apps. I hope this will be helpful
private func takePhoto() -> Void
{
if let videoConnection = stillImageOutput!.connection(withMediaType: AVMediaTypeVideo)
{
videoConnection.videoOrientation = AVCaptureVideoOrientation.portrait
stillImageOutput?.captureStillImageAsynchronously(from: videoConnection, completionHandler: { (sampleBuffer, error) in
guard let buffer = sampleBuffer else
{
return
}
let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(buffer)
let dataProvider = CGDataProvider(data: imageData as! CFData)
let cgImageRef = CGImage(jpegDataProviderSource: dataProvider!,
decode: nil,
shouldInterpolate: true,
intent: CGColorRenderingIntent.defaultIntent)
// The image taked
let image: UIImage = UIImage(cgImage: cgImageRef!, scale: 1.0, orientation: UIImageOrientation.right)
// Detenemos la captura de imagenes
self.captureSession!.stopRunning()
})
}
}
If you don't set the sessionPreset property of your captureSession variable, by default his values is AVCapture​Session​Preset​High. The only preset that is higher than this is AVCaptureSessionPresetPhoto