使用AVFoundation的视频的第一帧

Question

我正在尝试使用AVFoundation中的类来获取视频的第一帧.但它似乎根本没有得到一个图像.

我的代码目前看起来像这样

AVURLAsset* asset = [AVURLAsset URLAssetWithURL:[NSURL URLWithString:videoPath] options:nil];
AVAssetImageGenerator* imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
UIImage* image = [UIImage imageWithCGImage:[imageGenerator copyCGImageAtTime:CMTimeMake(0, 1) actualTime:nil error:nil]];
[videoFrame setImage:image];

视频路径的价值/var/mobile/Applications/02F42CBF-D8BD-4155-85F2-8CF1E55B5023/Documents/videos/1334300431637030.mp4绝对是一个视频,因为我可以播放它MPMoviePlayerViewController.我不确定我做错了什么,但任何建议都会有所帮助.

谢谢.

Answer 1

我解决了 显然使用[NSURL fileURLWithPath:videoPath]而不是[NSURL URLWithString:videoPath]使所有的差异.

Answer 2

我使用了null0pointer解决方案,但在一些视频中,我收到了第一帧旋转.要解决此问题,我将AVAssetImageGenerator的applyPreferredTrackTransform属性设置为TRUE.这段代码看起来像这样:

AVURLAsset* asset = [AVURLAsset URLAssetWithURL:fileURL options:nil];
AVAssetImageGenerator* imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
[imageGenerator setAppliesPreferredTrackTransform:TRUE];
UIImage* image = [UIImage imageWithCGImage:[imageGenerator copyCGImageAtTime:CMTimeMake(0, 1) actualTime:nil error:nil]];
[self.imageView setImage:image];

Answer 3

在Swift 4.0中执行此操作：

            // Assumes you have a local `fileURL`

            var avAsset = AVURLAsset(url: fileURL, options: nil)
            var imageGenerator = AVAssetImageGenerator(asset: avAsset)
            imageGenerator.appliesPreferredTrackTransform = true
            var thumbnail: UIImage?

            do {
                thumbnail = try UIImage(cgImage: imageGenerator.copyCGImage(at: CMTime(seconds: 0, preferredTimescale: 1), actualTime: nil))
            } catch let e as NSError {
                print("Error: \(e.localizedDescription)")
            }