ios – 如何使用AVCaptureVideoDataOutput录制视频

{

    var captureDevice = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo) as AVCaptureDevice

    var error: NSError? = nil

    do {

        //remove the prevIoUs inputs
        let inputs = cameraSession.inputs as! [AVCaptureDeviceInput]
        for oldInput:AVCaptureDeviceInput in inputs {
            cameraSession.removeInput(oldInput)
        }
        cameraSession.beginConfiguration()

        if cameraPosition.isEqualToString("Front") {
            captureDevice = cameraWithPosition(.Front)!
        }
        else {
            captureDevice = cameraWithPosition(.Back)!
        }

        let deviceInput = try AVCaptureDeviceInput(device: captureDevice)

        if (cameraSession.canAddInput(deviceInput) == true) {
            cameraSession.addInput(deviceInput)
        }

        let dataOutput = AVCaptureVideoDataOutput()
        dataOutput.videoSettings = [(kCVPixelBufferPixelFormatTypeKey as Nsstring) : NSNumber(unsignedInt: kCVPixelFormatType_420YpCbCr8BiPlanarFullRange)]
        dataOutput.alwaysdiscardsLateVideoFrames = true

        if (cameraSession.canAddOutput(dataOutput) == true) {
            cameraSession.addOutput(dataOutput)
        }

        let audioCheck = AVCaptureDevice.devicesWithMediaType(AVMediaTypeAudio)
        if audioCheck.isEmpty {
            print("no audio device")
            return
        }

        let audioDevice: AVCaptureDevice! = audioCheck.first as! AVCaptureDevice

        var audioDeviceInput: AVCaptureDeviceInput?

        do {
            audioDeviceInput = try AVCaptureDeviceInput(device: audioDevice)
        } catch let error2 as NSError {
            error = error2
            audioDeviceInput = nil
        } catch {
            fatalError()
        }

        if error != nil{
            print(error)
            let alert = UIAlertController(title: "Error",message: error!.localizedDescription,preferredStyle: .Alert)
            alert.addAction(UIAlertAction(title: "OK",style: .Default,handler: nil))
            self.presentViewController(alert,animated: true,completion: nil)
        }
        if cameraSession.canAddInput(audioDeviceInput){
            cameraSession.addInput(audioDeviceInput)
        }

        cameraSession.commitConfiguration()

        let queue = dispatch_queue_create("com.invasivecode.videoQueue",disPATCH_QUEUE_SERIAL)
        dataOutput.setSampleBufferDelegate(self,queue: queue)

    }
    catch let error as NSError {
        NSLog("\(error),\(error.localizedDescription)")
    }
}

使用AVCaptureMovieFileOutput可以使用照片库中的输出视频保存

movieFileOutput.startRecordingToOutputFileURL( outputFilePath,recordingDelegate: self)

但是我使用AVCaptureVideoDataOutput作为输出,以便从代理人获取的元数据进行额外的工作,并尝试录制视频,但无法获取任何方法来开始和停止录制视频.

建议如何使用AVCaptureVideoDataOutput录制视频