Didoutputsamplebuffer Delegate Not Called

didOutputSampleBuffer delegate not called

I found the problem of my error! It's because the delegate that was being called has to be created in the same view controller. here is the modified code:

import UIKit
import AVFoundation
import Accelerate

var customPreviewLayer: AVCaptureVideoPreviewLayer?

class ViewController: UIViewController,     AVCaptureVideoDataOutputSampleBufferDelegate {

var captureSession: AVCaptureSession?
var dataOutput: AVCaptureVideoDataOutput?
//var customPreviewLayer: AVCaptureVideoPreviewLayer?

@IBOutlet weak var camView: UIView!

override func viewWillAppear(animated: Bool) {
    super.viewDidAppear(animated)
    //setupCameraSession()
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    //captureSession?.startRunning()
    setupCameraSession()
    self.captureSession?.startRunning()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func setupCameraSession() {
    // Session
    self.captureSession = AVCaptureSession()
    self.captureSession!.sessionPreset = AVCaptureSessionPreset1920x1080
    // Capture device
    let inputDevice: AVCaptureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
    var deviceInput = AVCaptureDeviceInput()
    // Device input
    //var deviceInput: AVCaptureDeviceInput? = AVCaptureDeviceInput.deviceInputWithDevice(inputDevice, error: error)
    do {
        deviceInput = try AVCaptureDeviceInput(device: inputDevice)

    } catch let error as NSError {
        // Handle errors
        print(error)
    }
    if self.captureSession!.canAddInput(deviceInput) {
        self.captureSession!.addInput(deviceInput)
    }
    // Preview
    customPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    customPreviewLayer!.frame = camView.bounds
    customPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspect
    customPreviewLayer?.connection.videoOrientation = AVCaptureVideoOrientation.Portrait
    self.camView.layer.addSublayer(customPreviewLayer!)
    print("Cam layer added")

    self.dataOutput = AVCaptureVideoDataOutput()
    self.dataOutput!.videoSettings = [
        String(kCVPixelBufferPixelFormatTypeKey) : Int(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)
    ]

    self.dataOutput!.alwaysDiscardsLateVideoFrames = true
    if self.captureSession!.canAddOutput(dataOutput) {
        self.captureSession!.addOutput(dataOutput)
    }
    self.captureSession!.commitConfiguration()
    let queue: dispatch_queue_t = dispatch_queue_create("VideoQueue", DISPATCH_QUEUE_SERIAL)
    //let delegate = VideoDelegate()
    self.dataOutput!.setSampleBufferDelegate(self, queue: queue)
}

 func captureOutput(captureOutput: AVCaptureOutput, didOutputSampleBuffer sampleBuffer: CMSampleBufferRef, fromConnection connection: AVCaptureConnection) {
    print("buffered")
    let imageBuffer: CVImageBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer)!
    CVPixelBufferLockBaseAddress(imageBuffer, 0)
    let width: size_t = CVPixelBufferGetWidthOfPlane(imageBuffer, 0)
    let height: size_t = CVPixelBufferGetHeightOfPlane(imageBuffer, 0)
    let bytesPerRow: size_t = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, 0)
    let lumaBuffer: UnsafeMutablePointer = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0)
    let grayColorSpace: CGColorSpaceRef = CGColorSpaceCreateDeviceGray()!
    let context: CGContextRef = CGBitmapContextCreate(lumaBuffer, width, height, 8, bytesPerRow, grayColorSpace, CGImageAlphaInfo.PremultipliedLast.rawValue)!//problematic

    let dstImageFilter: CGImageRef = CGBitmapContextCreateImage(context)!
    dispatch_sync(dispatch_get_main_queue(), {() -> Void in
        customPreviewLayer!.contents = dstImageFilter as AnyObject
    })
}

}

AVCaptureVideoDataOutput captureOutput not being called

You need to define the didOutputSampleBuffer delegate callback to actually receive the captured frames:

func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {
    print("captured \(sampleBuffer)")
}

p.s. I'm not sure about macOS, but viewWillAppear may not be a good place to do initialisation because on iOS at least it can be called multiple times.

AVCaptureOutput didOutputSampleBuffer stops getting called

Your problem is actually referenced in the Docs, Specifically;

If your application is causing samples to be dropped by retaining the
provided CMSampleBufferRef objects for too long, but it needs access
to the sample data for a long period of time, consider copying the
data into a new buffer and then releasing the sample buffer (if it was
previously retained) so that the memory it references can be reused.

Essentially, you need to keep the callback operation as simple as possible, and should you need to perform further processing on the frame passed to you in the callback, you need to copy it to a new buffer and perform the processing in the background. Also, Keep in mind that Core Foundation object must explicitly be retained and released.

A further consideration is memory pressure. Frames contain lots of data, retaining too many will cause your app to crash.

captureOutput not being called

You made a mistake in declaration of required sample buffer delegate method:

captureOutput(_:didOutputSampleBuffer:from:).

Please check it and make sure it is:

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!)

PS: Pay attention on how parameters of that method are declared. All parameters have '!' which means automatic unwrapping.

AVCaptureDeviceOutput not calling delegate method captureOutput

Your session is a local variable. Its scope is limited to viewDidLoad. Since this is a new project, I assume it's safe to say that you're using ARC. In that case that object won't leak and therefore continue to live as it would have done in the linked question, rather the compiler will ensure the object is deallocated before viewDidLoad exits.

Hence your session isn't running because it no longer exists.

(aside: the self.theImage.image = ... is unsafe since it performs a UIKit action of the main queue; you probably want to dispatch_async that over to dispatch_get_main_queue())

So, sample corrections:

@implementation YourViewController
{
     AVCaptureSession *session;
}

- (void)viewDidLoad {

    [super viewDidLoad];

    // Initialize AV session    
        session = [AVCaptureSession new];

        if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone)
            [session setSessionPreset:AVCaptureSessionPreset640x480];
        else
         /* ... etc ... */
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {

        NSLog(@"delegate method called");

        CGImageRef cgImage = [self imageFromSampleBuffer:sampleBuffer];

        dispatch_sync(dispatch_get_main_queue(),
        ^{
            self.theImage.image = [UIImage imageWithCGImage: cgImage ];
            CGImageRelease( cgImage );
         });
}

Most people advocate using an underscore at the beginning of instance variable names nowadays but I omitted it for simplicity. You can use Xcode's built in refactor tool to fix that up after you've verified that the diagnosis is correct.

I moved the CGImageRelease inside the block sent to the main queue to ensure its lifetime extends beyond its capture into a UIImage. I'm not immediately able to find any documentation to confirm that CoreFoundation objects have their lifetime automatically extended when captured in a block.

A function is not getting called inside a delegate method - IOS/Swift

I was able to find a way to get my work done.But couldn't find what is wrong with my previous code. This is how it looks like

func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {

    let seconds: Int64 = 1 * Int64(NSEC_PER_SEC);

    let time = dispatch_time(DISPATCH_TIME_NOW, seconds);

    dispatch_after(time, dispatch_get_main_queue(), {
        //piece of code i want to run
    });
}

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