我试图从Swift中的视频中提取帧作为UIImages。我发现了几个Objective C解决方案,但我在Swift中找不到任何东西。假设以下是正确的,有人可以帮助我将以下内容转换为Swift或者给我自己如何做到这一点?
- (UIImage *)imageFromVideo:(NSURL *)videoURL atTime:(NSTimeInterval)time {
// courtesy of memmons
// http://stackoverflow.com/questions/1518668/grabbing-the-first-frame-of-a-video-from-uiimagepickercontroller
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
NSParameterAssert(asset);
AVAssetImageGenerator *assetIG =
[[AVAssetImageGenerator alloc] initWithAsset:asset];
assetIG.appliesPreferredTrackTransform = YES;
assetIG.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;
CGImageRef thumbnailImageRef = NULL;
CFTimeInterval thumbnailImageTime = time;
NSError *igError = nil;
thumbnailImageRef =
[assetIG copyCGImageAtTime:CMTimeMake(thumbnailImageTime, 60)
actualTime:NULL
error:&igError];
if (!thumbnailImageRef)
NSLog(@"thumbnailImageGenerationError %@", igError );
UIImage *image = thumbnailImageRef
? [[UIImage alloc] initWithCGImage:thumbnailImageRef]
: nil;
return image;
}
答案 0 :(得分:7)
它确实起作用了。
func imageFromVideo(url: URL, at time: TimeInterval) -> UIImage? {
let asset = AVURLAsset(url: url)
let assetIG = AVAssetImageGenerator(asset: asset)
assetIG.appliesPreferredTrackTransform = true
assetIG.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels
let cmTime = CMTime(seconds: time, preferredTimescale: 60)
let thumbnailImageRef: CGImage
do {
thumbnailImageRef = try assetIG.copyCGImage(at: cmTime, actualTime: nil)
} catch let error {
print("Error: \(error)")
return nil
}
return UIImage(cgImage: thumbnailImageRef)
}
但请记住,此功能是同步的,最好不要在主队列上调用它。
你可以这样做:
DispatchQueue.global(qos: .background).async {
let image = self.imageFromVideo(url: url, at: 0)
DispatchQueue.main.async {
self.imageView.image = image
}
}
或使用generateCGImagesAsynchronously
代替copyCGImage
。
答案 1 :(得分:0)
这是Dmitry解决方案的 SWIFT 5 替代方案,不必担心您正在排队吗?
public func imageFromVideo(url: URL, at time: TimeInterval, completion: @escaping (UIImage?) -> Void) {
DispatchQueue.global(qos: .background).async {
let asset = AVURLAsset(url: url)
let assetIG = AVAssetImageGenerator(asset: asset)
assetIG.appliesPreferredTrackTransform = true
assetIG.apertureMode = AVAssetImageGenerator.ApertureMode.encodedPixels
let cmTime = CMTime(seconds: time, preferredTimescale: 60)
let thumbnailImageRef: CGImage
do {
thumbnailImageRef = try assetIG.copyCGImage(at: cmTime, actualTime: nil)
} catch let error {
print("Error: \(error)")
return completion(nil)
}
DispatchQueue.main.async {
completion(UIImage(cgImage: thumbnailImageRef))
}
}
}
现在可以使用它:
imageFromVideo(url: videoUrl, at: 0) { image in
// Do something with the image here
}