How to output a CIFilter to a Camera view?

Question

I\'m just starting out in Objective-C and I\'m trying to create a simple app where it shows the camera view with a blur effect on it. I got the Camera output working with the AV

Answer 1

Here's something to get you started. This is an updated version of the code from the following link.
https://gist.github.com/eladb/9662102

The trick is to use the AVCaptureVideoDataOutputSampleBufferDelegate.
With this delegate, you can use imageWithCVPixelBuffer to construct a CIImage from your camera buffer.

Right now though I'm trying to figure out how to reduce lag. I'll update asap.

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Update: Latency is now minimal, and on some effects unnoticeable. Unfortunately, it seems that blur is one of the slowest. You may want to look into vImage.

---

#import "ViewController.h"
#import 
#import 

@interface ViewController () {

}

@property (strong, nonatomic) CIContext *coreImageContext;
@property (strong, nonatomic) AVCaptureSession *cameraSession;
@property (strong, nonatomic) AVCaptureVideoDataOutput *videoOutput;
@property (strong, nonatomic) UIView *blurCameraView;
@property (strong, nonatomic) CIFilter *filter;
@property BOOL cameraOpen;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.blurCameraView = [[UIView alloc]initWithFrame:[[UIScreen mainScreen] bounds]];
    [self.view addSubview:self.blurCameraView];

    //setup filter
    self.filter = [CIFilter filterWithName:@"CIGaussianBlur"];
    [self.filter setDefaults];
    [self.filter setValue:@(3.0f) forKey:@"inputRadius"];

    [self setupCamera];
    [self openCamera];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)setupCamera
{
    self.coreImageContext = [CIContext contextWithOptions:@{kCIContextUseSoftwareRenderer : @(YES)}];

    // session
    self.cameraSession = [[AVCaptureSession alloc] init];
    [self.cameraSession setSessionPreset:AVCaptureSessionPresetLow];
    [self.cameraSession commitConfiguration];

    // input
    AVCaptureDevice *shootingCamera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    AVCaptureDeviceInput *shootingDevice = [AVCaptureDeviceInput deviceInputWithDevice:shootingCamera error:NULL];
    if ([self.cameraSession canAddInput:shootingDevice]) {
        [self.cameraSession addInput:shootingDevice];
    }

    // video output
    self.videoOutput = [[AVCaptureVideoDataOutput alloc] init];
    self.videoOutput.alwaysDiscardsLateVideoFrames = YES;
    [self.videoOutput setSampleBufferDelegate:self queue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0)];
    if ([self.cameraSession canAddOutput:self.videoOutput]) {
        [self.cameraSession addOutput:self.videoOutput];
    }

    if (self.videoOutput.connections.count > 0) {
        AVCaptureConnection *connection = self.videoOutput.connections[0];
        connection.videoOrientation = AVCaptureVideoOrientationPortrait;
    }

    self.cameraOpen = NO;
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    // Get a CMSampleBuffer's Core Video image buffer for the media data
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    // turn buffer into an image we can manipulate
    CIImage *result = [CIImage imageWithCVPixelBuffer:imageBuffer];

    // filter
    [self.filter setValue:result forKey:@"inputImage"];

    // render image
    CGImageRef blurredImage = [self.coreImageContext createCGImage:self.filter.outputImage fromRect:result.extent];
    dispatch_async(dispatch_get_main_queue(), ^{
        self.blurCameraView.layer.contents = (__bridge id)blurredImage;
        CGImageRelease(blurredImage);
    });
}

- (void)openCamera {
    if (self.cameraOpen) {
        return;
    }

    self.blurCameraView.alpha = 0.0f;
    [self.cameraSession startRunning];
    [self.view layoutIfNeeded];

    [UIView animateWithDuration:3.0f animations:^{

        self.blurCameraView.alpha = 1.0f;

    }];

    self.cameraOpen = YES;
}