Question

这是Apple的代码（来自Technical Q＆amp; A QA1702），用于从视频缓冲区获取UIImage。不幸的是，返回的图像旋转了90度。如何编辑它以使返回的图像正确定向？

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer 
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
    CVPixelBufferLockBaseAddress(imageBuffer, 0); 

    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); 

    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
    size_t width = CVPixelBufferGetWidth(imageBuffer); 
    size_t height = CVPixelBufferGetHeight(imageBuffer); 

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 

    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, 
                                                 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 

    CGImageRef quartzImage = CGBitmapContextCreateImage(context); 
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);

    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace);

    UIImage *image = [UIImage imageWithCGImage:quartzImage];

    CGImageRelease(quartzImage);

    return (image);
}

Answer 1

取决于您使用的是前置摄像头还是后置摄像头

int frontCameraImageOrientation = UIImageOrientationLeftMirrored;
int backCameraImageOrientation = UIImageOrientationRight;

UIImage *image = [[UIImage alloc] initWithCGImage:newImage scale:(CGFloat)1.0 orientation:frontCameraImageOrientation];

Answer 2

您可以更改videoOrientation，这样您就可以获得正确的图像

connection.videoOrientation = AVCaptureVideoOrientationPortrait

因为默认情况下，视频方向不是肖像。

Answer 3

只需旋转上下文

只需以弧度旋转上下文即可。此调用会将上下文旋转90度。

CGFloat degrees = 90.f;
CGFloat radians = degrees * (M_PI / 180.f);
CGContextRotateCTM(context, radians);

您可以轻松设置此方法以获得所需的方向并相应地旋转。

旋转从视频帧中获取的CGImage

3 个答案:

只需旋转上下文