Getting image from AVCaptureMovieFileOutput without switching

Question

I would like to prevent lags when the app switches between video-recording and photo-taking: by using only AVCaptureMovieFileOutput and getting a snapshot from it when captured an image.

Just like how SnapChat does.

Is it possible somehow? I haven't found any releated articles about this.

I don't want to switch between outputs, because it lags

The code:

@IBOutlet var cameraView: UIView!

@IBOutlet var cameraSwitchButton: UIButton!
@IBOutlet var captureButtonView: CaptureButton!
@IBOutlet var cameraFlashButton: UIButton!

var captureSession = AVCaptureSession()
let movieOutput = AVCaptureMovieFileOutput()
var activeInput: AVCaptureDeviceInput!
var previewLayer = AVCaptureVideoPreviewLayer()

var outputURL: URL!

var connection : AVCaptureConnection!


override func viewDidLoad() {

    if setupSession() {
        setupPreview()
        startSession()
        connection = movieOutput.connection(with: AVMediaType.video)
        if (connection?.isVideoStabilizationSupported)! {
            connection?.preferredVideoStabilizationMode = AVCaptureVideoStabilizationMode.off
        }
    }


    let tapGesture = UITapGestureRecognizer(target: self, action: #selector(captureButtonTapped))
    let longGesture = UILongPressGestureRecognizer(target: self, action: #selector(captureButtonLongPressed))
    tapGesture.numberOfTapsRequired = 1
    captureButtonView.addGestureRecognizer(tapGesture)
    captureButtonView.addGestureRecognizer(longGesture)

}

@objc func captureButtonTapped(){

    ?? TAKE PHOTO HERE ??


}
var isRecordingVideo : Bool = false
@objc func captureButtonLongPressed(sender : UILongPressGestureRecognizer){
    if sender.state == .began {
        isRecordingVideo = true

        startRecording()
        captureButtonView.startTimer(duration: 10.0)

    }

    if sender.state == .ended || sender.state == .failed || sender.state == .cancelled {
        captureButtonView.clear()
        isRecordingVideo = false
        stopRecording()
    }
}


func setupPreview() {
    // Configure previewLayer
    previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    previewLayer.frame = cameraView.bounds
    previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
    cameraView.layer.addSublayer(previewLayer)
}

//MARK:- Setup Camera

func setupSession() -> Bool {

    captureSession.sessionPreset = AVCaptureSession.Preset.high

    // Setup Camera
    let camera = AVCaptureDevice.default(for: AVMediaType.video)

    do {
        let input = try AVCaptureDeviceInput(device: camera!)
        if captureSession.canAddInput(input) {
            captureSession.addInput(input)
            activeInput = input
        }
    } catch {
        print("Error setting device video input: \(error)")
        return false
    }

    // Setup Microphone
    let microphone = AVCaptureDevice.default(for: AVMediaType.audio)

    do {
        let micInput = try AVCaptureDeviceInput(device: microphone!)
        if captureSession.canAddInput(micInput) {
            captureSession.addInput(micInput)
        }
    } catch {
        print("Error setting device audio input: \(error)")
        return false
    }


    // Movie output
    if captureSession.canAddOutput(movieOutput) {
        captureSession.addOutput(movieOutput)
    }

    return true
}

func setupCaptureMode(_ mode: Int) {

}

//MARK:- Camera Session
func startSession() {


    if !captureSession.isRunning {
        videoQueue().async {
            self.captureSession.startRunning()
        }
    }
}

func stopSession() {
    if captureSession.isRunning {
        videoQueue().async {
            self.captureSession.stopRunning()
        }
    }
}

func videoQueue() -> DispatchQueue {
    return DispatchQueue.main
}

func currentVideoOrientation() -> AVCaptureVideoOrientation {
    var orientation: AVCaptureVideoOrientation

    switch UIDevice.current.orientation {
    case .portrait:
        orientation = AVCaptureVideoOrientation.portrait
    case .landscapeRight:
        orientation = AVCaptureVideoOrientation.landscapeLeft
    case .portraitUpsideDown:
        orientation = AVCaptureVideoOrientation.portraitUpsideDown
    default:
        orientation = AVCaptureVideoOrientation.landscapeRight
    }

    return orientation
}

func startCapture() {

    startRecording()

}

func tempURL() -> URL? {
    let directory = NSTemporaryDirectory() as NSString

    if directory != "" {
        let path = directory.appendingPathComponent(NSUUID().uuidString + ".mp4")
        return URL(fileURLWithPath: path)
    }

    return nil
}


func startRecording() {

    if movieOutput.isRecording == false {


        if (connection?.isVideoOrientationSupported)! {
            connection?.videoOrientation = currentVideoOrientation()
        }

        let device = activeInput.device
        if (device.isSmoothAutoFocusSupported) {
            do {
                try device.lockForConfiguration()
                device.isSmoothAutoFocusEnabled = false
                device.unlockForConfiguration()
            } catch {
                print("Error setting configuration: \(error)")
            }

        }

        outputURL = tempURL()
        movieOutput.startRecording(to: outputURL, recordingDelegate: self)

    }
    else {
        stopRecording()
    }

}

func stopRecording() {

    if movieOutput.isRecording == true {
        movieOutput.stopRecording()
    }
}


func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) {
    if (error != nil) {
        print("Error recording movie: \(error!.localizedDescription)")
    } else {

        UISaveVideoAtPathToSavedPhotosAlbum(outputURL.path, nil, nil, nil)

        _ = outputURL as URL

    }
    outputURL = nil
}

Answer 1

I wasn't able to find a way using only AVCaptureMovieFileOutput, however you can add an additional photo output and trigger photos without having to switch between the outputs.

I'm short on time at the moment but this should get you going till I can edit with more info.

(See EDIT with full implementation below, and limited force unwrapping)

First off setup an additional var for a photo output in your view controller

// declare an additional camera output var
var cameraOutput = AVCapturePhotoOutput()

// do this in your 'setupSession' func where you setup your movie output
cameraOutput.isHighResolutionCaptureEnabled = true
captureSession.addOutput(cameraOutput)

Declare a function to capture your photo using the cameraOutput:

func capturePhoto() {
    // create settings for your photo capture
    let settings = AVCapturePhotoSettings()
    let previewPixelType = settings.availablePreviewPhotoPixelFormatTypes.first!
    let previewFormat = [
        kCVPixelBufferPixelFormatTypeKey as String: previewPixelType,
        kCVPixelBufferWidthKey as String: UIScreen.main.bounds.size.width,
        kCVPixelBufferHeightKey as String: UIScreen.main.bounds.size.height
        ] as [String : Any]
    settings.previewPhotoFormat = previewFormat
    cameraOutput.capturePhoto(with: settings, delegate: self)
}

and conform to the AVCapturePhotoCaptureDelegate.

I created a separate class called VideoFeed to manage the video capture session, so this sample is an extension of that class. I'll update with more info on this later.

The loadImage(data: Data) function calls a delegate with the image. You can ignore that call if you put this directly in your view controller, and save or do whatever you like with the generated photo:

extension VideoFeed: AVCapturePhotoCaptureDelegate {
    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photoSampleBuffer: CMSampleBuffer?, previewPhoto previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {
        guard error == nil else {
            print("Photo Error: \(String(describing: error))")
            return
        }

        guard let sampleBuffer = photoSampleBuffer,
            let previewBuffer = previewPhotoSampleBuffer,
            let outputData =  AVCapturePhotoOutput
            .jpegPhotoDataRepresentation(forJPEGSampleBuffer: sampleBuffer, previewPhotoSampleBuffer: previewBuffer) else {
                    print("Oops, unable to create jpeg image")
            return
        }

        print("captured photo...")
        loadImage(data: outputData)
    }

    func loadImage(data: Data) {
        let dataProvider = CGDataProvider(data: data as CFData)
        let cgImageRef: CGImage! = CGImage(jpegDataProviderSource: dataProvider!, decode: nil, shouldInterpolate: true, intent: .defaultIntent)
        let image = UIImage(cgImage: cgImageRef, scale: 1.0, orientation: UIImageOrientation.right)
        // do whatever you like with the generated image here...
        delegate?.processVideoSnapshot(image)
    }
}

EDIT:

Here's the complete implementation I used in my test project.

First I moved all the AVFoundation specific code into it's own VideoFeed class and created some callbacks to the view controller.

This separates concerns and limits the view controllers responsibilities to:

• Adding the preview layer to the view
• Triggering and handling the captured image/screenshot
• Starting/stopping video file recording.

Here's the ViewController implementation:

ViewController.swift

import UIKit
import AVFoundation


class ViewController: UIViewController, VideoFeedDelegate {

    @IBOutlet var cameraView: UIView!

    var videoFeed: VideoFeed?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        // end session
        videoFeed?.stopSession()
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        // request camera access
        AVCaptureDevice.requestAccess(for: AVMediaType.video) { [weak self] granted in
            guard granted != false else {
                // TODO: show UI stating camera cannot be used, update in settings app...
                print("Camera access denied")
                return
            }
            DispatchQueue.main.async {

                if self?.videoFeed == nil {
                    // video access was enabled so setup video feed
                    self?.videoFeed = VideoFeed(delegate: self)
                } else {
                    // video feed already available, restart session...
                    self?.videoFeed?.startSession()
                }

            }
        }
    }

    // MARK: VideoFeedDelegate
    func videoFeedSetup(with layer: AVCaptureVideoPreviewLayer) {

        // set the layer size
        layer.frame = cameraView.layer.bounds

        // add to view
        cameraView.layer.addSublayer(layer)
    }

    func processVideoSnapshot(_ image: UIImage?) {

        // validate
        guard let image = image else {
            return
        }

        // SAVE IMAGE HERE IF DESIRED

        // for now just showing in a lightbox/detail view controller
        let storyboard = UIStoryboard(name: "Main", bundle: Bundle(for: AppDelegate.self))
        let vc = storyboard.instantiateViewController(withIdentifier: "LightboxViewController") as! LightboxViewController
        vc.previewImage = image
        navigationController?.pushViewController(vc, animated: true)
    }

    @IBAction func captureButtonTapped(_ sender: Any){

        // trigger photo capture from video feed...
        // this will trigger a callback to the function above with the captured image
        videoFeed?.capturePhoto()
    }
}

Here's the full implementation of the VideoFeed class.

Using this approach allows you to reuse the video functionality in other projects more easily without having it tightly coupled to the view controller.

VideoFeed.swift

import UIKit
import AVFoundation

/// Defines callbacks associated with the VideoFeed class. Notifies delegate of significant events.
protocol VideoFeedDelegate: class {

    /// Callback triggered when the preview layer for this class has been created and configured. Conforming objects should set and maintain a strong reference to this layer otherwise it will be set to nil when the calling function finishes execution.
    ///
    /// - Parameter layer: The video preview layer associated with the active captureSession in the VideoFeed class.
    func videoFeedSetup(with layer: AVCaptureVideoPreviewLayer)

    /// Callback triggered when a snapshot of the video feed has been generated.
    ///
    /// - Parameter image: <#image description#>
    func processVideoSnapshot(_ image: UIImage?)
}

class VideoFeed: NSObject {

    // MARK: Variables

    /// The capture session to be used in this class.
    var captureSession = AVCaptureSession()

    /// The preview layer associated with this session. This class has a
    /// weak reference to this layer, the delegate (usually a ViewController 
    /// instance) should add this layer as a sublayer to its preview UIView. 
    /// The delegate will have the strong reference to this preview layer.
    weak var previewLayer: AVCaptureVideoPreviewLayer?

    /// The output that handles saving the video stream to a file.
    var fileOutput: AVCaptureMovieFileOutput?

    /// A reference to the active video input
    var activeInput: AVCaptureDeviceInput?

    /// Output for capturing frame grabs of video feed
    var cameraOutput = AVCapturePhotoOutput()

    /// Delegate to receive callbacks about significant events triggered by this class.
    weak var delegate: VideoFeedDelegate?

    /// The capture connection associated with the fileOutput. 
    /// Set when fileOutput is created.
    var connection : AVCaptureConnection?


    // MARK: Public accessors

    /// Public initializer. Accepts a delegate to receive callbacks with the preview layer and any snapshot images.
    ///
    /// - Parameter delegate: A reference to an object conforming to VideoFeedDelegate 
    /// to receive callbacks for significant events in this class.
    init(delegate: VideoFeedDelegate?) {
        self.delegate = delegate
        super.init()
        setupSession()
    }

    /// Public accessor to begin a capture session.
    public func startSession() {
        guard captureSession.isRunning == false else {
            return
        }

        captureSession.startRunning()
    }

    /// Public accessor to end the current capture session.
    public func stopSession() {

        // validate
        guard captureSession.isRunning else {
            return
        }

        // end file recording if the session ends and we're currently recording a video to file
        if let isRecording = fileOutput?.isRecording, isRecording {
            stopRecording()
        }

        captureSession.stopRunning()
    }

    /// Public accessor to begin file recording.
    public func startRecording() {

        guard fileOutput?.isRecording == false else {
            stopRecording()
            return
        }

        configureVideoOrientation()
        disableSmoothAutoFocus()

        guard let url = tempURL() else {
            print("Unable to start file recording, temp url generation failed.")
            return
        }

        fileOutput?.startRecording(to: url, recordingDelegate: self)
    }

    /// Public accessor to end file recording.
    public func stopRecording() {
        guard fileOutput?.isRecording == true else {
            return
        }

        fileOutput?.stopRecording()
    }

    /// Public accessor to trigger snapshot capture of video stream.
    public func capturePhoto() {

        // create settings object
        let settings = AVCapturePhotoSettings()

        // verify that we have a pixel format type available
        guard let previewPixelType = settings.availablePreviewPhotoPixelFormatTypes.first else {
            print("Unable to configure photo capture settings, 'availablePreviewPhotoPixelFormatTypes' has no available options.")
            return
        }

        let screensize = UIScreen.main.bounds.size

        // setup format configuration dictionary
        let previewFormat: [String : Any] = [
            kCVPixelBufferPixelFormatTypeKey as String: previewPixelType,
            kCVPixelBufferWidthKey as String: screensize.width,
            kCVPixelBufferHeightKey as String: screensize.height
            ]
        settings.previewPhotoFormat = previewFormat

        // trigger photo capture
        cameraOutput.capturePhoto(with: settings, delegate: self)
    }

    // MARK: Setup functions

    /// Handles configuration and setup of the session, inputs, video preview layer and outputs.
    /// If all are setup and configured it starts the session.
    internal func setupSession() {

        captureSession.sessionPreset = AVCaptureSession.Preset.high
        guard setupInputs() else {
            return
        }

        setupOutputs()
        setupVideoLayer()
        startSession()
    }

    /// Sets up capture inputs for this session.
    ///
    /// - Returns: Returns true if inputs are successfully setup, else false.
    internal func setupInputs() -> Bool {

        // only need access to this functionality within this function, so declare as sub-function
        func addInput(input: AVCaptureInput) {
            guard captureSession.canAddInput(input) else {
                return
            }

            captureSession.addInput(input)
        }

        do {
            if let camera = AVCaptureDevice.default(for: AVMediaType.video) {
                let input = try AVCaptureDeviceInput(device: camera)
                addInput(input: input)
                activeInput = input
            }

            // Setup Microphone
            if let microphone = AVCaptureDevice.default(for: AVMediaType.audio) {
                let micInput = try AVCaptureDeviceInput(device: microphone)
                addInput(input: micInput)
            }

            return true
        } catch {
            print("Error setting device video input: \(error)")
            return false
        }
    }

    internal func setupOutputs() {

        // only need access to this functionality within this function, so declare as sub-function
        func addOutput(output: AVCaptureOutput) {
            if captureSession.canAddOutput(output) {
                captureSession.addOutput(output)
            }
        }

        // file output
        let fileOutput = AVCaptureMovieFileOutput()
        captureSession.addOutput(fileOutput)

        if let connection = fileOutput.connection(with: .video), connection.isVideoStabilizationSupported {
            connection.preferredVideoStabilizationMode = .off
            self.connection = connection
        }

        cameraOutput.isHighResolutionCaptureEnabled = true
        captureSession.addOutput(cameraOutput)

    }

    internal func setupVideoLayer() {
        let layer =  AVCaptureVideoPreviewLayer(session: captureSession)
        layer.videoGravity = AVLayerVideoGravity.resizeAspectFill
        delegate?.videoFeedSetup(with: layer)
        previewLayer = layer
    }

    // MARK: Helper functions

    /// Creates a url in the temporary directory for file recording.
    ///
    /// - Returns: A file url if successful, else nil.
    internal func tempURL() -> URL? {
        let directory = NSTemporaryDirectory() as NSString

        if directory != "" {
            let path = directory.appendingPathComponent(NSUUID().uuidString + ".mp4")
            return URL(fileURLWithPath: path)
        }

        return nil
    }

    /// Disables smooth autofocus functionality on the active device, 
    /// if the active device is set and 'isSmoothAutoFocusSupported' 
    /// is supported for the currently set active device.
    internal func disableSmoothAutoFocus() {

        guard let device = activeInput?.device, device.isSmoothAutoFocusSupported else {
            return
        }

        do {
            try device.lockForConfiguration()
            device.isSmoothAutoFocusEnabled = false
            device.unlockForConfiguration()
        } catch {
            print("Error disabling smooth autofocus: \(error)")
        }

    }

    /// Sets the current AVCaptureVideoOrientation on the currently active connection if it's supported.
    internal func configureVideoOrientation() {

        guard let connection = connection, connection.isVideoOrientationSupported,
        let currentOrientation = AVCaptureVideoOrientation(rawValue: UIApplication.shared.statusBarOrientation.rawValue) else {
                return
        }

        connection.videoOrientation = currentOrientation
    }
}

// MARK: AVCapturePhotoCaptureDelegate
extension VideoFeed: AVCapturePhotoCaptureDelegate {

    // iOS 11+ processing
    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
        guard error == nil, let outputData = photo.fileDataRepresentation() else {
            print("Photo Error: \(String(describing: error))")
            return
        }

        print("captured photo...")
        loadImage(data: outputData)
    }

    // iOS < 11 processing
    func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photoSampleBuffer: CMSampleBuffer?, previewPhoto previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {

        if #available(iOS 11.0, *) {
            // use iOS 11-only feature
            // nothing to do here as iOS 11 uses the callback above
        } else {
            guard error == nil else {
                print("Photo Error: \(String(describing: error))")
                return
            }

            guard let sampleBuffer = photoSampleBuffer,
                let previewBuffer = previewPhotoSampleBuffer,
                let outputData =  AVCapturePhotoOutput
                .jpegPhotoDataRepresentation(forJPEGSampleBuffer: sampleBuffer, previewPhotoSampleBuffer: previewBuffer) else {
                        print("Image creation from sample buffer/preview buffer failed.")
                        return
            }

            print("captured photo...")
            loadImage(data: outputData)
        }
    }

    /// Creates a UIImage from Data object received from AVCapturePhotoOutput 
    /// delegate callback and sends to the VideoFeedDelegate for handling.
    ///
    /// - Parameter data: Image data.
    internal func loadImage(data: Data) {
        guard let dataProvider = CGDataProvider(data: data as CFData), let cgImageRef: CGImage = CGImage(jpegDataProviderSource: dataProvider, decode: nil, shouldInterpolate: true, intent: .defaultIntent) else {
            return
        }
        let image = UIImage(cgImage: cgImageRef, scale: 1.0, orientation: UIImageOrientation.right)
        delegate?.processVideoSnapshot(image)
    }
}

extension VideoFeed: AVCaptureFileOutputRecordingDelegate {

    func fileOutput(_ output: AVCaptureFileOutput, didStartRecordingTo fileURL: URL, from connections: [AVCaptureConnection]) {
        print("Video recording started: \(fileURL.absoluteString)")
    }

    func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) {

        guard error == nil else {
            print("Error recording movie: \(String(describing: error))")
            return
        }

        UISaveVideoAtPathToSavedPhotosAlbum(outputFileURL.path, nil, nil, nil)
    }
}

For anyone else making use of this, don't forget to add permissions to your info.plist for access to the camera, photo library and microphone.

<key>NSCameraUsageDescription</key>
<string>Let us use your camera</string>
<key>NSPhotoLibraryAddUsageDescription</key>
<string>save to images</string>
<key>NSMicrophoneUsageDescription</key>
<string>for sound in video</string>