AVCaptureSession rotation

Question

I'm trying to get my app to create a UIImage the correct way round.

Most of my code is taken from Apple examples...

@interface CameraManager () <AVCaptureVideoDataOutputSampleBufferDelegate>

@property (nonatomic, strong) CIContext *context;
@property (nonatomic, strong) AVCaptureDevice *rearCamera;

@end

@implementation CameraManager

- (id)init {
    if ((self = [super init])) {

        self.context = [CIContext contextWithOptions:nil];
        [self setupCamera];
        [self addStillImageOutput];
    }
    return self;
}

- (void)setupCamera
{
    self.session = [[AVCaptureSession alloc] init];
    [self.session beginConfiguration];

    [self.session setSessionPreset:AVCaptureSessionPresetPhoto];

    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    self.rearCamera = nil;
    for (AVCaptureDevice *device in devices) {
        if (device.position == AVCaptureDevicePositionBack) {
            self.rearCamera = device;
            break;
        }
    }

    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:self.rearCamera error:&error];
    [self.session addInput:input];

    AVCaptureVideoDataOutput *dataOutput = [[AVCaptureVideoDataOutput alloc] init];
    [dataOutput setAlwaysDiscardsLateVideoFrames:YES];

    NSDictionary *options = @{(id)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32BGRA)};
    [dataOutput setVideoSettings:options];

    [dataOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];

    [self.session addOutput:dataOutput];
    [self.session commitConfiguration];
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    // grab the pixel buffer
    CVPixelBufferRef pixelBuffer = (CVPixelBufferRef) CMSampleBufferGetImageBuffer(sampleBuffer);

    // create a CIImage from it, rotate it and zero the origin
    CIImage *image = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationLandscapeLeft) {
        image = [image imageByApplyingTransform:CGAffineTransformMakeRotation(M_PI)];
    }
    CGPoint origin = [image extent].origin;
    image = [image imageByApplyingTransform:CGAffineTransformMakeTranslation(-origin.x, -origin.y)];

    // set it as the contents of the UIImageView
    CGImageRef cgImage = [self.context createCGImage:image fromRect:[image extent]];
    UIImage *uiImage = [UIImage imageWithCGImage:cgImage];

    [[NSNotificationCenter defaultCenter] postNotificationName:@"image" object:uiImage];

    CGImageRelease(cgImage);
}

- (void)addStillImageOutput
{
    [self setStillImageOutput:[[AVCaptureStillImageOutput alloc] init]];
    NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey,nil];
    [[self stillImageOutput] setOutputSettings:outputSettings];

    AVCaptureConnection *videoConnection = nil;
    for (AVCaptureConnection *connection in [self.stillImageOutput connections]) {
        for (AVCaptureInputPort *port in [connection inputPorts]) {
            if ([[port mediaType] isEqual:AVMediaTypeVideo] ) {
                videoConnection = connection;
                break;
            }
        }
        if (videoConnection) {
            break;
        }
    }

    [[self session] addOutput:[self stillImageOutput]];
}

- (void)captureStillImage
{
    AVCaptureConnection *videoConnection = nil;
    for (AVCaptureConnection *connection in [[self stillImageOutput] connections]) {
        for (AVCaptureInputPort *port in [connection inputPorts]) {
            if ([[port mediaType] isEqual:AVMediaTypeVideo]) {
                videoConnection = connection;
                break;
            }
        }
        if (videoConnection) {
            break;
        }
    }

    NSLog(@"about to request a capture from: %@", [self stillImageOutput]);
    [[self stillImageOutput] captureStillImageAsynchronouslyFromConnection:videoConnection
                                                         completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error) {
                                                             CFDictionaryRef exifAttachments = CMGetAttachment(imageSampleBuffer, kCGImagePropertyExifDictionary, NULL);
                                                             if (exifAttachments) {
                                                                 NSLog(@"attachements: %@", exifAttachments);
                                                             } else {
                                                                 NSLog(@"no attachments");
                                                             }
                                                             NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
                                                             UIImage *image = [[UIImage alloc] initWithData:imageData];

                                                             [[NSNotificationCenter defaultCenter] postNotificationName:kImageCapturedSuccessfully object:image];
                                                         }];
}

This is my camera manager class code.

I am displaying the preview of the camera using the OutputSampleBufferDelegate (for various reasons).

I'm using the session output to "take a photo".

The method captureStillImage is the bit I'm trying to fix.

The photos are taken with the device in LandscapeLeft orientation (the interface is also LandscapeLeft).

The previews all show the correct way around and the exif data shows the width and height the correct way around too. (X = 3264, Y = 2448).

But when I display the UIImage it is rotated 90 degrees counter clockwise. The aspect ratio of the image is correct (i.e. everything looks fine, circles are still circles) just the rotation.

I have found several categories that claim to fix this.

I have also found several StackOverflow questions with answers that also claim to fix it.

None of these worked.

Does anyone know how to rotate this thing the right way around?

Answer 1

Adding the following code before you call captureStillImageAsynchronouslyFromConnection is what I do usually:

if ([videoConnection isVideoOrientationSupported]) {
    [videoConnection setVideoOrientation:[UIDevice currentDevice].orientation];
}

Answer 2

Maybe you should try setting image orientation after receiving image data in captureStillImageAsynchronouslyFromConnection completion block:

UIImage *image = [[UIImage alloc] initWithData:imageData];
image = [[UIImage alloc] initWithCGImage:image.CGImage scale:1.0f orientation:UIImageOrientationDown];