如何使用cv :: VideoCapture访问视频的最后一帧?
在OpenCVViewController.h中:
@interface OpenCVViewController : UIViewController {
cv::VideoCapture *_videoCapture;
cv::Mat _lastFrame;
AVCaptureVideoPreviewLayer *_previewLayer;
UIView *_videoPreviewView;
}
@property(nonatomic, retain) IBOutlet UIButton *captureButton;
@property(nonatomic, retain) IBOutlet UIView *videoPreviewView;
@property(nonatomic, retain) AVCaptureVideoPreviewLayer *previewLayer;
- (IBAction)capture:(id)sender;
@end
在OpenCVViewController.mm中:
- (void)viewDidLoad {
[super viewDidLoad];
_videoCapture = new cv::VideoCapture;
if (!_videoCapture->open(CV_CAP_AVFOUNDATION)) {
NSLog(@"Open video camera failed");
}
AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPresetHigh;
CALayer *viewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
_previewLayer.frame = _videoPreviewView.bounds;
[_videoPreviewView.layer addSublayer:_previewLayer];
AVCaptureDevice *device = [AVCaptureDeviceInput defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = nil;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input) {
NSLog(@"Error opening camera: %@", error);
}
[session addInput:input];
[session startRunning];
}
- (IBAction)capture:(id)sender {
_captureButton.enabled = NO;
if (_videoCapture && _videoCapture->grab()) {
(*_videoCapture) >> _lastFrame; //Line is hit
}
else {
NSLog("Failed to grab frame");
}
}
按下捕获按钮时,我想抓取videoCapture中的最后一帧并将数据保存到_lastFrame中。使用上面显示的方法,在IBAction中,_last框架为空。
是否有其他方法可以抓取一个帧并使用_lastFrame稍后处理图像?
提前致谢!使用iOS 6和opencv2框架
答案 0 :(得分:0)
您应该尝试使用VideoCapture::read,它结合了grab()和retrieve()。
另外,我认为read()和retrieve()都返回对VideoCapture Buffer的引用,因此你需要使用cvCloneImage()来操作框架。