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iospreviewcropavcapturesession

Cropping an AVCaptureSession preview

I'm displaying a video preview of a 320x320 capture window, and using videoGravity to have it fill the square:

captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

I'm then grabbing a photo quality image from the session and cropping it, starting at 0, 0. The problem I have is the saved image shows more to the top (but not left) of the frame than the preview. I'd like to basically only see the top of the frame, it seems I'm seeing the middle section, hope I'm explaining myself properly.

Here is the code snippet if it helps:

AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
captureVideoPreviewLayer.frame = _cameraView.bounds;
[_cameraView.layer addSublayer:captureVideoPreviewLayer];
captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

Thanks in advance for any help.

Cheers.

Solution

  • I couldn't figure out how to do this, so I decided to fix it by changing the cropping region instead of the preview region.