Съемка экрана во время предварительного просмотра видео

Я пытаюсь захватить экран во время предварительного просмотра видео с помощью AVFoundation (AVCaptureDeviceInput и AVCaptureVideoDataOutput).

Запустить предварительный просмотр:

func startCamera(){
    var screenSize = UIScreen.mainScreen().bounds.size;
    self.previewView = UIView(frame: CGRectMake(0, 0, UIScreen.mainScreen().bounds.size.width, UIScreen.mainScreen().bounds.size.height));
    self.previewView.contentMode = UIViewContentMode.ScaleAspectFit
    self.view.addSubview(previewView);

    session.sessionPreset = AVCaptureSessionPresetHigh

    let devices = AVCaptureDevice.devices();
    // Loop through all the capture devices on this phone
    for device in devices {
        // Make sure this particular device supports video
        if (device.hasMediaType(AVMediaTypeVideo)) {
            // Finally check the position and confirm we've got the front camera
            if(device.position == AVCaptureDevicePosition.Back) {
                captureDevice = device as? AVCaptureDevice;
                if captureDevice != nil {
                    beginSession();
                    break;
                }
            }
        }
    }
}

func beginSession() {
    var err : NSError? = nil
    var deviceInput:AVCaptureDeviceInput = AVCaptureDeviceInput(device: captureDevice!, error: &err);

    if err != nil {
        println("error: \(err?.localizedDescription)");
    }
    if session.canAddInput(deviceInput){
        session.addInput(deviceInput);
    }

    videoDataOutput = AVCaptureVideoDataOutput()

    if let videoDataOutput = videoDataOutput {
        var rgbOutputSettings = [NSNumber(integer: kCMPixelFormat_32BGRA):kCVPixelBufferPixelFormatTypeKey]
        videoDataOutput.alwaysDiscardsLateVideoFrames=true;
        videoDataOutput.setSampleBufferDelegate(self, queue:self.videoDataOutputQueue)
        if session.canAddOutput(self.videoDataOutput){
            session.addOutput(self.videoDataOutput)
        }
        videoDataOutput.connectionWithMediaType(AVMediaTypeVideo).enabled = true

        if let previewLayer = AVCaptureVideoPreviewLayer(session: self.session) {
            self.previewLayer = previewLayer
            previewLayer.videoGravity = AVLayerVideoGravityResizeAspect
            previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.LandscapeRight

            var rootLayer :CALayer = self.previewView.layer;
            rootLayer.masksToBounds=true;
            previewLayer.frame = rootLayer.bounds;
            rootLayer.addSublayer(self.previewLayer);
            session.startRunning();

            delay(8, closure: { () -> () in
                self.processImage()
            })
        }
    }
}

Код для захвата экрана:

func processImage() {
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, false, 0)
    previewLayer!.renderInContext(UIGraphicsGetCurrentContext())
    // tried previewView!.layer.render... to no avail
    let previewImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    savePDFImage(previewImage, name: "front.pdf")
}

Возвращаемое изображение просто белое. Как я могу получить снимок экрана о том, что на экране при просмотре видео?

var videoDataOutput:AVCaptureVideoDataOutput?; var videoDataOutputQueue:dispatch_queue_t = dispatch_queue_create("VideoDataOutputQueue", DISPATCH_QUEUE_SERIAL); var stillImageOutput:AVCaptureStillImageOutput? var previewLayer:AVCaptureVideoPreviewLayer? var captureDevice:AVCaptureDevice? let session = AVCaptureSession() func beginSession() { var err : NSError? = nil var deviceInput:AVCaptureDeviceInput = AVCaptureDeviceInput(device: captureDevice!, error: &err); if err != nil { println("error: \(err?.localizedDescription)"); } if session.canAddInput(deviceInput){ session.addInput(deviceInput); } stillImageOutput = AVCaptureStillImageOutput() videoDataOutput = AVCaptureVideoDataOutput() if let videoDataOutput = videoDataOutput, stillImageOutput = stillImageOutput { videoDataOutput.alwaysDiscardsLateVideoFrames=true; videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey:Int(kCVPixelFormatType_32BGRA)] videoDataOutput.setSampleBufferDelegate(self, queue:self.videoDataOutputQueue) if session.canAddOutput(videoDataOutput){ session.addOutput(videoDataOutput) } stillImageOutput.outputSettings = [AVVideoCodecKey:AVVideoCodecJPEG] if session.canAddOutput(stillImageOutput) { session.addOutput(stillImageOutput) } videoDataOutput.connectionWithMediaType(AVMediaTypeVideo).enabled = true if let previewLayer = AVCaptureVideoPreviewLayer(session: self.session) { self.previewLayer = previewLayer previewLayer.videoGravity = AVLayerVideoGravityResizeAspect previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.LandscapeRight var rootLayer :CALayer = self.previewView.layer; rootLayer.masksToBounds=true; previewLayer.frame = rootLayer.bounds; rootLayer.addSublayer(self.previewLayer); session.startRunning(); } } } // this gets called periodically with an image func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!) { if let image = CheckResponse.imageFromSampleBuffer(sampleBuffer) { if keepImage(image) { AudioServicesPlaySystemSound(1108) session.stopRunning() } } } // This is in the Objective-C CheckResponse class to get an image from the buffer: + (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer { CVPixelBufferRef pb = CMSampleBufferGetImageBuffer(sampleBuffer); CIImage *ciimg = [CIImage imageWithCVPixelBuffer:pb]; // show result CIContext *context = [CIContext contextWithOptions:nil]; CGImageRef ref = [context createCGImage:ciimg fromRect:ciimg.extent]; UIImage *image = [UIImage imageWithCGImage:ref scale:1.0 orientation:(UIImageOrientationUp)]; CFRelease(ref); return image; }

Ответ 1