didOutputSampleBuffer Delegate Never Gets Called (iOS / Swift 3) - ios

Question

I am trying to keep track of the sample buffer rate of a video recording.
I have a view controller with AVCaptureFileOutputRecordingDelegate and AVCaptureVideoDataOutputSampleBufferDelegate and then setting the buffer output like so:
sessionQueue.async { [weak self] in
if let `self` = self {
let movieFileOutput = AVCaptureMovieFileOutput()
let bufferQueue = DispatchQueue(label: "bufferRate", qos: .userInteractive, attributes: .concurrent)
let theOutput = AVCaptureVideoDataOutput()
theOutput.videoSettings = [(kCVPixelBufferPixelFormatTypeKey as NSString): NSNumber(value:kCVPixelFormatType_32BGRA)]
theOutput.alwaysDiscardsLateVideoFrames = true
theOutput.setSampleBufferDelegate(self, queue: bufferQueue)
if self.session.canAddOutput(theOutput) {
self.session.addOutput(theOutput)
print("ADDED BUFFER OUTPUT")
}
if self.session.canAddOutput(movieFileOutput) {
self.session.beginConfiguration()
self.session.addOutput(movieFileOutput)
self.session.sessionPreset = AVCaptureSessionPresetHigh
if let connection = movieFileOutput.connection(withMediaType: AVMediaTypeVideo) {
if connection.isVideoStabilizationSupported {
connection.preferredVideoStabilizationMode = .auto
}
}
self.session.commitConfiguration()
self.movieFileOutput = movieFileOutput
DispatchQueue.main.async { [weak self] in
if let `self` = self {
self.recordButton.isEnabled = true
}
}
}
}
}
Additionally, I have the function put into place to read the buffer:
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
print("captured \(sampleBuffer)")
}
The problem is that when running the camera, it records correctly like it is supposed to (code not shown as it is working like normal) but the captureOutput sample buffer never gets called. What am I doing wrong? I assume it has to do with the way I am setting it up?

Answer 1

Make sure the delegate signature is correct with Swift 3 syntax.
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection)
I was using Swift 2.3 syntax and compiler did not warn me of the issue. try to type out the didOut sampleBuffer and check if XCode autocorrects the proper syntax for that delegate method.