Add audio to my video when recording - Swift 4 - ios

Question

I'm trying to add audio when I record video. I know that I have to record it separately and combine them when I save the file, but I cant figure out the syntax or where to add my audio device and where to combine the files.
Most of the information available is based on older deprecated syntax or only deal with one subject (Video, vs. Audio etc.)
I have different functions for preparing the session, displaying the session and recording the session and saving the outputFile that looks like this code that is based on the tutorial from "Zero2Launch" https://www.youtube.com/watch?v=7TqXrMnfJy8
but for the life of me I cant figure out what to do with the audio.
func setupCaptureSession() {
captureSession.sessionPreset = AVCaptureSession.Preset.hd1920x1080
}
func setupDevice() {
let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: AVMediaType.video, position: AVCaptureDevice.Position.unspecified)
let devices = deviceDiscoverySession.devices
for device in devices {
if device.position == AVCaptureDevice.Position.back {
backCamera = device
} else if device.position == AVCaptureDevice.Position.front {
frontCamera = device
}
}
currentDevice = backCamera
}
func setupInputOutput() {
do {
let captureDeviceInput = try AVCaptureDeviceInput(device: currentDevice!)
captureSession.addInput(captureDeviceInput)
videoFileOutput = AVCaptureMovieFileOutput()
captureSession.addOutput(videoFileOutput!)
} catch {
print(error)
}
}
func setupPreviewLayer() {
cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
cameraPreviewLayer?.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
cameraPreviewLayer?.frame = self.view.frame
self.view.layer.insertSublayer(cameraPreviewLayer!, at: 0)
}
func startRunningCaptureSession() {
captureSession.startRunning()
}
func recordVideo() {
if !isRecording {
isRecording = true
UIView.animate(withDuration: 0.5, delay: 0.0, options: [.repeat, .autoreverse, .allowUserInteraction], animations: { () -> Void in
self.recordButton.transform = CGAffineTransform(scaleX: 0.5, y: 0.5)
}, completion: nil)
let outputPath = NSTemporaryDirectory() + "output.mov"
let outputFileURL = URL(fileURLWithPath: outputPath)
videoFileOutput?.startRecording(to: outputFileURL, recordingDelegate: self)
} else {
isRecording = false
UIView.animate(withDuration: 0.5, delay: 1.0, options: [], animations: { () -> Void in
self.recordButton.transform = CGAffineTransform(scaleX: 1.0, y: 1.0)
}, completion: nil)
recordButton.layer.removeAllAnimations()
videoFileOutput?.stopRecording()
}
}
func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) {
if error != nil {
print(error)
return
}
UISaveVideoAtPathToSavedPhotosAlbum(outputFileURL.relativePath, self, nil, nil)
}

Answer 1

You don't need to save audio separately and merge them. You have only to do add audioDeviceInput to your session inputs and AVCaptureMovieFileOutput will do everything for you. try to change setupInputOutput method
func setupInputOutput() {
guard let audioDevice = AVCaptureDevice.default(for: .audio) else { return }
do {
let captureDeviceInput = try AVCaptureDeviceInput(device: currentDevice!)
let audioDeviceInput = try AVCaptureDeviceInput(device: audioDevice)
captureSession.addInput(captureDeviceInput)
captureSession.addInput(audioDeviceInput)
videoFileOutput = AVCaptureMovieFileOutput()
captureSession.addOutput(videoFileOutput!)
} catch {
print(error)
}
}
there are second way to record video and audio using AVCaptureVideoDataOutput, AVCaptureAudioDataOutput and AVAssetWriter classes but a little complicate. if you don't need to change video or audio buffer in realtime it better to use AVCaptureMovieFileOutput