Video Buffer Output with Swift - ios

Question

My goal is to take the video buffer and ultimately convert it to NSData but I do not understand how to access the buffer properly. I have the captureOutput function but I have not been successful if converting the buffer and I'm not sure I am actually collecting anything in the buffer. This is all using swift code, I have found some examples using Objective-C but I am not able to understand the Obj-c code well enough to figure it out.
var captureDevice : AVCaptureDevice?
var videoCaptureOutput = AVCaptureVideoDataOutput()
var bounds: CGRect = UIScreen.mainScreen().bounds
let captureSession = AVCaptureSession()
var captureConnection: AVCaptureMovieFileOutput?
override func viewDidLoad() {
super.viewDidLoad()
captureSession.sessionPreset = AVCaptureSessionPreset640x480
let devices = AVCaptureDevice.devices()
for device in devices {
if (device.hasMediaType(AVMediaTypeVideo)) {
if device.position == AVCaptureDevicePosition.Back {
captureDevice = device as? AVCaptureDevice
if captureDevice != nil {
beginSession()
}
}
}
}
}
func beginSession() {
var screenWidth:CGFloat = bounds.size.width
var screenHeight:CGFloat = bounds.size.height
var err : NSError? = nil
captureSession.addInput(AVCaptureDeviceInput(device: captureDevice, error: &err)!)
if err != nil {
println("Error: \(err?.localizedDescription)")
}
videoCaptureOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey:kCVPixelFormatType_32BGRA]
videoCaptureOutput.alwaysDiscardsLateVideoFrames = true
captureSession.addOutput(videoCaptureOutput)
videoCaptureOutput.setSampleBufferDelegate(self, queue: dispatch_queue_create("sample buffer delegate", DISPATCH_QUEUE_SERIAL))
if captureSession.canAddOutput(self.videoCaptureOutput) {
captureSession.addOutput(self.videoCaptureOutput)
}
func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) {
// I think this is where I can get the buffer info.
}

Answer 1

In the AVCaptureVideoDataOutputSampleBufferDelegate method, captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!), you can get the buffer info
let formatDescription: CMFormatDescription = CMSampleBufferGetFormatDescription(sampleBuffer)
let imageBuffer: CVImageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
CVPixelBufferLockBaseAddress(imageBuffer, 0)
var imagePointer: UnsafeMutablePointer<Void> = CVPixelBufferGetBaseAddress(imageBuffer)
let bufferSize: (width: Int, height: Int) = (CVPixelBufferGetHeight(imageBuffer), CVPixelBufferGetWidth(imageBuffer))
println("Buffer Size: \(bufferSize.width):\(bufferSize.height)")