AVFoundation - Why my image would fail on output?

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I don't know why my capture raw data would return null. Input and Output of the capture seems to declared correctly. I am trying to have r,g,b color of specific pixel from live camera view. I am not sure which part of the function is not making it work.

---

#import "PCamViewController.h"

@interface PCamViewController ()

@end

@implementation PCamViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self startSession];    
}

- (AVCaptureSession *)session
{
    if (!_session) {
        _session = [[AVCaptureSession alloc]init];
    }
    return _session;
}

- (AVCaptureDeviceInput *)deviceInput
{
    if (!_deviceInput) {
        _deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] error:nil];
    }
    return _deviceInput;
}

- (void) startSession {

    [self.session addInput:self.deviceInput];

    AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
    [previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    CALayer *rootLayer = [self.captureView layer];
    [rootLayer setMasksToBounds:YES];
    CGRect boundCapture = self.captureView.bounds;
    [previewLayer setFrame:boundCapture];
    [rootLayer insertSublayer:previewLayer atIndex:0];

    [self.session startRunning];

    stillImageOutput = [AVCaptureStillImageOutput new];
    if ([_session canAddOutput:stillImageOutput])
        [_session addOutput:stillImageOutput];

    NSLog(@"session activated");
}

- (IBAction)captureImage:(UIButton *)sender {
    NSLog(@"captureImage button pushed");
    AVCaptureConnection *stillImageConnection = [stillImageOutput connectionWithMediaType:AVMediaTypeVideo];

    [stillImageOutput captureStillImageAsynchronouslyFromConnection:[[stillImageOutput connections] objectAtIndex:0] completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error) {
        CVImageBufferRef cameraFrame = CMSampleBufferGetImageBuffer(imageSampleBuffer);
        CVPixelBufferLockBaseAddress(cameraFrame, 0);
        GLubyte *rawImageBytes = CVPixelBufferGetBaseAddress(cameraFrame);
        size_t bytesPerRow = CVPixelBufferGetBytesPerRow(cameraFrame);
        NSData *dataForRawBytes = [NSData dataWithBytes:rawImageBytes length:bytesPerRow * CVPixelBufferGetHeight(cameraFrame)];
        // Do whatever with your bytes
        NSLog(@"%@", dataForRawBytes);
        NSLog(@"%@", rawImageBytes);
        //NSLog(@"%@", imageSampleBuffer);

        CVPixelBufferUnlockBaseAddress(cameraFrame, 0);
    }];
}
@end

asked 46 secs ago

fkkcloud

41