How do I save the video in the correct orientation?

Question

I have a camera in my app that can change the orientation.
Initially, the camera orientation is set from the current device orientation.

captureSession.addOutput(videoOutput!)
cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
cameraPreviewLayer?.connection?.videoOrientation = AVCaptureVideoOrientation(rawValue: UIDevice.current.orientation.rawValue) ?? .portrait

When rotating, I change the camera orientation.

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        coordinator.animate(alongsideTransition: nil) { _ in UIView.setAnimationsEnabled(true) }
        UIView.setAnimationsEnabled(false)
        super.viewWillTransition(to: size, with: coordinator)

        Logger.Log("VIEW WILL TRANSITION")
        if let videoOrientation = AVCaptureVideoOrientation(rawValue: UIDevice.current.orientation.rawValue) {
            Logger.Log("videoOrientation updated")
            cameraPreviewLayer?.connection?.videoOrientation = videoOrientation
        }

        cameraPreviewLayer?.frame.size = size
    }

After the recording is completed, I transfer the video URL to the AVPlayer. And you can see that the player plays the video in the wrong orientation.

if let _ = link {
            let player = AVPlayer(url: link!)
            self.player = player
            self.player?.play()

        }

For example, this is how I record in landscape orientation.

And I get the following result. Although the result should look the other way around.

On the server, it is also stored in the wrong orientation.

I watched this question. But it seems I already assign the orientation when recording.

I also watched this question. I tried to see if the video that the player plays is different in different orientations. But I always get the same result.

func playLink(){
        if let _ = link {
            let player = AVPlayer(url: link!)
            self.player = player
            self.player?.play()

        }

        let videoAssetTrack = self.player?.currentItem?.asset.tracks(withMediaType: .video).first
        let videoTransform = videoAssetTrack?.preferredTransform

        Logger.Log("videoTransform = \(videoTransform)")
    }

videoTransform = Optional(__C.CGAffineTransform(a: 0.0, b: 1.0, c: -1.0, d: 0.0, tx: 1080.0, ty: 0.0))

Help me please, what should I do to get the correct result on the output?

Answer 1

Apparently at first I did the wrong thing in this answer.
I just took out the connection and orientation as global fields of the whole class and addressed them.
Now I have added the following code and this solves my problem.

var currentOrientation: AVCaptureVideoOrientation?
var videoConnection: AVCaptureConnection?

captureSession.addOutput(videoOutput!)

            videoConnection = videoOutput!.connection(with: .video)

            if (videoConnection!.isVideoOrientationSupported) {
                Logger.Log("connection!.isVideoOrientationSupported")
                if let capOr = AVCaptureVideoOrientation(rawValue: UIDevice.current.orientation.rawValue) {
                    Logger.Log("connection!.videoOrientation = \(capOr.rawValue)")
                    currentOrientation = capOr
                    videoConnection!.videoOrientation = currentOrientation!
                } else {
                    currentOrientation = .portrait
                    videoConnection!.videoOrientation = currentOrientation!
                }
            }

cameraPreviewLayer?.connection?.videoOrientation = currentOrientation! 

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        coordinator.animate(alongsideTransition: nil) { _ in UIView.setAnimationsEnabled(true) }
        UIView.setAnimationsEnabled(false)
        super.viewWillTransition(to: size, with: coordinator)

        Logger.Log("VIEW WILL TRANSITION")
        if let videoOrientation = AVCaptureVideoOrientation(rawValue: UIDevice.current.orientation.rawValue) {
            Logger.Log("videoOrientation updated = \(videoOrientation.rawValue)")

            currentOrientation = videoOrientation
            videoConnection?.videoOrientation = currentOrientation!
            cameraPreviewLayer?.connection?.videoOrientation = currentOrientation!
        }

        cameraPreviewLayer?.frame.size = size
    }