Getting image from AVCaptureMovieFileOutput without switching - swift

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>