AVAssetImageGenerator provides images rotated

Question

When obtaining a UIImage of a video via AVAssetImageGenerator, I'm getting back images rotated (well, technically they're not) when the video is shot in portrait orientation. How can I tell what orientation the video was shot and then rotate the image properly?

AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:url options:nil];
AVAssetImageGenerator *generate = [[AVAssetImageGenerator alloc] initWithAsset:asset];
NSError *err = NULL;
CMTime time = CMTimeMake(0, 60);
CGImageRef imgRef = [generate copyCGImageAtTime:time actualTime:NULL error:&err];
[generate release];
UIImage *currentImg = [[UIImage alloc] initWithCGImage:imgRef];

score 239 · Accepted Answer · answered Mar 18 '11 at 03:51

239

The easiest way is to just set the appliesPreferredTrackTransform property on the image generator to YES, then it should automatically do the transformation for you.

answered Mar 18 '11 at 03:51

Anomie

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Many thanks! I skimmed the docs but the name of this property just didn't suggest to me it had anything to do with the problem. – E-Madd Mar 18 '11 at 04:02
For some reason, setting it to `YES` (also tried `NO` too, no difference) didn't do anything and it's still rotated. (the asset is encapsulated by a `GPUImageMovie`, if that helps). – Can Poyrazoğlu Apr 17 '17 at 07:03

score 25 · Answer 2 · answered Apr 29 '14 at 19:52

The copy and paste solution to create image with the recording orientation using the previous answer.

AVURLAsset* asset = [AVURLAsset URLAssetWithURL:url options:nil];
AVAssetImageGenerator* imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
imageGenerator.appliesPreferredTrackTransform = YES;
CGImageRef cgImage = [imageGenerator copyCGImageAtTime:CMTimeMake(0, 1) actualTime:nil error:nil];
UIImage* image = [UIImage imageWithCGImage:cgImage];

CGImageRelease(cgImage);

score 8 · Answer 3 · answered May 13 '18 at 07:09

Here is the solution in swift version 4:

func thumbnailImageForFileUrl(_ fileUrl: URL) -> UIImage? {
    let asset = AVAsset(url: fileUrl)
    let imageGenerator = AVAssetImageGenerator(asset: asset)
    imageGenerator.appliesPreferredTrackTransform = true

    do {

        let thumbnailCGImage = try imageGenerator.copyCGImage(at: CMTimeMake(1, 60), actualTime: nil)
        return UIImage(cgImage: thumbnailCGImage)

    } catch let err {
        print(err)
    }

    return nil
}

score 1 · Answer 4 · answered Mar 17 '22 at 12:58

the easiest way is

imageGenerator.appliesPreferredTrackTransform = true

the hardest way is to change image orientation by this code:

let orient: UIImage.Orientation = isVertical ? .left: .up
imageView.image = UIImage(cgImage: image.cgImage!, scale: image.scale, orientation: orient)

AVAssetImageGenerator provides images rotated

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