如何在横屏模式下捕获AVFoundation而不是竖屏模式

Question

需要帮助，已经修复了几个小时但没有成功。

我想捕捉图像并在AVCaptureVideoPreviewLayer中显示预览，它以横向模式显示。然而，当我抓取图像时，它以纵向模式显示。

我不确定原因，希望有人可以帮助我 :)

谢谢阅读。

实时查看时 捕获并在uiimageview中显示时

- (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 captureSession] 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 isVideoOrientationSupported]) 
        {
            UIInterfaceOrientation orientation = [UIApplication sharedApplication].statusBarOrientation;

             if (orientation == UIInterfaceOrientationLandscapeLeft ) {
                 //NSLog(@"2222UIInterfaceOrientationLandscapeLeft");

            [videoConnection setVideoOrientation:AVCaptureVideoOrientationLandscapeLeft];
             }
             if (orientation == UIInterfaceOrientationLandscapeRight ) 
             {//NSLog(@"222UIInterfaceOrientationLandscapeRight");

            [videoConnection setVideoOrientation:AVCaptureVideoOrientationLandscapeRight];
             }

        }
        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];

        //NSData *jpgImageData = UIImageJPEGRepresentation(image, 0.9);
        //UIImage *jpgImage = [[UIImage alloc]initWithData:jpgImageData];
        [self setStillImage:image];
        self.imageExifDict = (__bridge NSDictionary *)exifAttachments;
                ////NSLog(@"NSdictionary from CFDict %@",self.imageExifDict);
//
        [[NSNotificationCenter defaultCenter] postNotificationName:kImageCapturedSuccessfully object:nil];

            }];
}

我将NSData中的图像转换为UIImage。

self.capturedImage.image = [[self captureManager] stillImage];

- Desmond

---

你能贴一些代码吗？我也遇到了同样的问题，想在AVCaptureVideoPreviewLayer中显示横向模式。 - user2545330

@user2545330编辑了我的帖子。希望它有所帮助！ - Desmond

Answer 1

我使用了这个C函数：

UIImage *scaleAndRotateImage(UIImage *image)
{
int kMaxResolution = 2048; // Or whatever

CGImageRef imgRef = image.CGImage;

CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);

CGAffineTransform transform = CGAffineTransformIdentity;
CGRect bounds = CGRectMake(0, 0, width, height);
if (width > kMaxResolution || height > kMaxResolution) {
    CGFloat ratio = width/height;

    if (ratio > 1) {
        bounds.size.width = kMaxResolution;
        bounds.size.height = bounds.size.width / ratio;
    }
    else {
        bounds.size.height = kMaxResolution;
        bounds.size.width = bounds.size.height * ratio;
    }
}

CGFloat scaleRatio = bounds.size.width / width;
CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef));
CGFloat boundHeight;
UIImageOrientation orient = image.imageOrientation;
switch(orient) {

    case UIImageOrientationUp: //EXIF = 1
        transform = CGAffineTransformIdentity;
        break;

    case UIImageOrientationUpMirrored: //EXIF = 2
        transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0);
        transform = CGAffineTransformScale(transform, -1.0, 1.0);
        break;

    case UIImageOrientationDown: //EXIF = 3
        transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
        transform = CGAffineTransformRotate(transform, M_PI);
        break;

    case UIImageOrientationDownMirrored: //EXIF = 4
        transform = CGAffineTransformMakeTranslation(0.0, imageSize.height);
        transform = CGAffineTransformScale(transform, 1.0, -1.0);
        break;

    case UIImageOrientationLeftMirrored: //EXIF = 5
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width);
        transform = CGAffineTransformScale(transform, -1.0, 1.0);
        transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
        break;

    case UIImageOrientationLeft: //EXIF = 6
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeTranslation(0.0, imageSize.width);
        transform = CGAffineTransformRotate(transform, 3.0 * M_PI / 2.0);
        break;

    case UIImageOrientationRightMirrored: //EXIF = 7
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeScale(-1.0, 1.0);
        transform = CGAffineTransformRotate(transform, M_PI / 2.0);
        break;

    case UIImageOrientationRight: //EXIF = 8
        boundHeight = bounds.size.height;
        bounds.size.height = bounds.size.width;
        bounds.size.width = boundHeight;
        transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
        transform = CGAffineTransformRotate(transform, M_PI / 2.0);
        break;

    default:
        [NSException raise:NSInternalInconsistencyException format:@"Invalid image orientation"];

}

UIGraphicsBeginImageContext(bounds.size);

CGContextRef context = UIGraphicsGetCurrentContext();

if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) {
    CGContextScaleCTM(context, -scaleRatio, scaleRatio);
    CGContextTranslateCTM(context, -height, 0);
}
else {
    CGContextScaleCTM(context, scaleRatio, -scaleRatio);
    CGContextTranslateCTM(context, 0, -height);
}

CGContextConcatCTM(context, transform);

CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef);
UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

return imageCopy;
}

这个：

int kMaxResolution = 2048; // Or whatever

因为我在使用具有该分辨率的新iPad。

更多信息：http://blog.logichigh.com/2008/06/05/uiimage-fix/

- silvaric

Answer 2

你漏掉了一件事情... 根据应用的方向设置AVCaptureVideoPreviewLayer方向。

例如： 对于iOS 6及以上版本，请使用

previewLayer.connection.videoOrientation=AVCaptureVideoOrientationLandscapeLeft;

适用于iOS 5

previewLayer.orientation=AVCaptureVideoOrientationLandscapeLeft;

- user3608500