ios - captureStillImageAsynchronouslyFromConnection 中 UIImage 的方向：AVCaptureConnection 的连接

Question

我正在使用以下方法从AVCaptureStillImageOutput捕获帧

- (void)captureImage:(void(^)(NSError*, UIImage*))completionHandler {
    AVCaptureConnection *connection = [_photoOutput connectionWithMediaType:AVMediaTypeVideo];
    if (connection != nil) {
        [_photoOutput captureStillImageAsynchronouslyFromConnection:connection completionHandler:
         ^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {

             if (imageDataSampleBuffer != nil && error == nil) {
                 NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                 if (jpegData) {
                     UIImage *image = [UIImage imageWithData:jpegData];
                     if (completionHandler != nil) {
                         completionHandler(nil, image);
                     }
                 } else {
                     if (completionHandler != nil) {
                         completionHandler([SCRecorder createError:@"Failed to create jpeg data"], nil);
                     }
                 }
             } else {
                 if (completionHandler != nil) {
                     completionHandler(error, nil);
                 }
             }
         }];
    } else {
        if (completionHandler != nil) {
            completionHandler([SCRecorder createError:@"Camera session not started or Photo disabled"], nil);
        }
    }
}

即使使用纵向做

if ([captureConnection isVideoOrientationSupported]) {
    captureConnection.videoOrientation = AVCaptureVideoOrientationPortrait;
}

我无法在缓冲区中旋转生成的图像。

我试图直接从缓冲区和旋转中获取图像

    // Create a UIImage from sample buffer data
- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer  {
    // Get a CMSampleBuffer's Core Video image buffer for the media data
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    // Lock the base address of the pixel buffer
    CVPixelBufferLockBaseAddress(imageBuffer, 0);

    // Get the number of bytes per row for the pixel buffer
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);

    // Get the number of bytes per row for the pixel buffer
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    // Get the pixel buffer width and height
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);

    // Create a device-dependent RGB color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // Create a bitmap graphics context with the sample buffer data
    CGContextRef context1 = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                  bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);

    // Create a Quartz image from the pixel data in the bitmap graphics context
    CGImageRef quartzImage = CGBitmapContextCreateImage(context1);
    // Unlock the pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);

    // Free up the context and color space
    CGContextRelease(context1);
    CGColorSpaceRelease(colorSpace);

    // Create an image object from the Quartz image
    //I modified this line: [UIImage imageWithCGImage:quartzImage]; to the following to correct the orientation:
    UIImage *image =  [UIImage imageWithCGImage:quartzImage scale:1.0 orientation:UIImageOrientationRight];

    // Release the Quartz image
    CGImageRelease(quartzImage);

    return (image);
}

但是我应该从captureStillImageAsynchronouslyFromConnection:connection传递的CMSampleBufferRef得到的结果CVImageBufferRef是 nil：

[_photoOutput captureStillImageAsynchronouslyFromConnection:connection completionHandler:
         ^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
   CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(imageDataSampleBuffer); 
// The image buffer ref is nil.

如果我尝试旋转直接从输出数据缓冲区获取的图像表示，例如：

NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                 if (jpegData) {
                     UIImage *image = [UIImage imageWithData:jpegData];
                      UIImage *image =  [UIImage imageWithCGImage:quartzImage scale:1.0 orientation:UIImageOrientationRight]; 
             }

生成的 UIImage 它没有得到正确的方向，通过 XCode QuickLook 和 po 来查看它。