63

我正在尝试从 iphone 3GS 相机拍摄的视频中获取缩略图（第一帧），以便显示它。这该怎么做？

4

12 回答 12

73 
-(UIImage *)generateThumbImage : (NSString *)filepath
{
    NSURL *url = [NSURL fileURLWithPath:filepath];

    AVAsset *asset = [AVAsset assetWithURL:url];
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];
    imageGenerator.appliesPreferredTrackTransform = YES;
    CMTime time = [asset duration];
    time.value = 0;
    CGImageRef imageRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:NULL];
    UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);  // CGImageRef won't be released by ARC

    return thumbnail;
}

您可以使用 time.value 获取帧假设您想要 1 秒帧然后使用

time.value = 1000 //Time in milliseconds
于 2014-01-20T09:44:52.070 回答
69

这个问题的答案是现在可以在 4.0 iOS 中使用 AVFoundation 获取缩略图，下面的类属性 url 是电影 url 的代码就可以解决问题（您可以随时获取缩略图，在示例中位于时间 0)

-(void)generateImage
{
    AVURLAsset *asset=[[AVURLAsset alloc] initWithURL:self.url options:nil];
    AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    generator.appliesPreferredTrackTransform=TRUE;
    [asset release];
    CMTime thumbTime = CMTimeMakeWithSeconds(0,30);

    AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error){
        if (result != AVAssetImageGeneratorSucceeded) {
            NSLog(@"couldn't generate thumbnail, error:%@", error);
        }
        [button setImage:[UIImage imageWithCGImage:im] forState:UIControlStateNormal];
        thumbImg=[[UIImage imageWithCGImage:im] retain];
        [generator release];
    };

    CGSize maxSize = CGSizeMake(320, 180);
    generator.maximumSize = maxSize;
    [generator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:[NSValue valueWithCMTime:thumbTime]] completionHandler:handler];

}
于 2010-12-02T00:43:29.407 回答
23 
NSURL *videoURL = [NSURL fileURLWithPath:url];

MPMoviePlayerController *player = [[MPMoviePlayerController alloc] initWithContentURL:videoURL];

        UIImage *thumbnail = [player thumbnailImageAtTime:1.0 timeOption:MPMovieTimeOptionNearestKeyFrame];

        //Player autoplays audio on init
        [player stop];
        [player release];

检查此链接以获取替代方案： thumbnailImageAtTime: now deprecated - 什么是替代方案？

于 2011-05-17T06:54:09.907 回答
14

我找到的最好的方法...MPMoviePlayerController thumbnailImageAtTime:timeOption

于 2010-08-25T03:46:24.513 回答
14

斯威夫特 2.0

您可以通过两种方式快速生成 1. AVFoundation 2. MPMoviePlayerController

1. 

    func generateThumnail(url : NSURL) -> UIImage{
            var asset : AVAsset = AVAsset.assetWithURL(url) as AVAsset
            var assetImgGenerate : AVAssetImageGenerator = AVAssetImageGenerator(asset: asset)
            assetImgGenerate.appliesPreferredTrackTransform = true
            var error       : NSError? = nil
            var time        : CMTime = CMTimeMake(1, 30)
            var img         : CGImageRef = assetImgGenerate.copyCGImageAtTime(time, actualTime: nil, error: &error)
            var frameImg    : UIImage = UIImage(CGImage: img)!
            
            return frameImg
        }

2. 

    override func viewDidLoad() {
            super.viewDidLoad()
            var moviePlayer         : MPMoviePlayerController!  = MPMoviePlayerController(contentURL: moviePlayManager.movieURL)
            moviePlayer.view.frame   = CGRect(x: self.view.frame.origin.x, y: self.view.frame.origin.y, width:
                                       self.view.frame.size.width, height: self.view.frame.height)
            moviePlayer.fullscreen   = true
            moviePlayer.controlStyle = MPMovieControlStyle.None
            NSNotificationCenter.defaultCenter().addObserver(self,
        selector: "videoThumbnailIsAvailable:",
        name: MPMoviePlayerThumbnailImageRequestDidFinishNotification,
        object: nil)


        let thumbnailTimes = 3.0
        moviePlayer.requestThumbnailImagesAtTimes([thumbnailTimes],
                timeOption: .NearestKeyFrame)
        }
    
    func videoThumbnailIsAvailable(notification: NSNotification){
        
        if let player = moviePlayer{
            let thumbnail =
            notification.userInfo![MPMoviePlayerThumbnailImageKey] as? UIImage
            
            if let image = thumbnail{
                
                /* We got the thumbnail image. You can now use it here */
                println("Thumbnail image = \(image)")
            }
        }
于 2015-03-09T06:55:35.073 回答
8

斯威夫特 2 代码：

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

    var time = asset.duration
    //If possible - take not the first frame (it could be completely black or white on camara's videos)
    time.value = min(time.value, 2)

    do {
        let imageRef = try imageGenerator.copyCGImageAtTime(time, actualTime: nil)
        return UIImage(CGImage: imageRef)
    }
    catch let error as NSError
    {
        print("Image generation failed with error \(error)")
        return nil
    }
}
于 2015-08-08T16:36:32.480 回答
8

对于 Swift 3.0

func createThumbnailOfVideoFromFileURL(_ strVideoURL: String) -> UIImage?{

let asset = AVAsset(url: URL(string: strVideoURL)!)
let assetImgGenerate = AVAssetImageGenerator(asset: asset)
assetImgGenerate.appliesPreferredTrackTransform = true
let time = CMTimeMakeWithSeconds(Float64(1), 100)
do {
  let img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
  let thumbnail = UIImage(cgImage: img)
  return thumbnail
} catch {
  /* error handling here */
}
return nil   }
于 2016-12-23T14:39:19.743 回答
2

斯威夫特 4

func generateThumbnail(for asset:AVAsset) -> UIImage? {
    let assetImgGenerate : AVAssetImageGenerator = AVAssetImageGenerator(asset: asset)
    assetImgGenerate.appliesPreferredTrackTransform = true
    let time = CMTimeMake(value: 1, timescale: 2)
    let img = try? assetImgGenerate.copyCGImage(at: time, actualTime: nil)
    if img != nil {
        let frameImg  = UIImage(cgImage: img!)
       return frameImg
    }
    return nil
}

如何使用：

   func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    picker.dismiss(animated: true) {

        switch mediaType {
        case kUTTypeMovie:
            guard info[UIImagePickerController.InfoKey.mediaType] != nil, let url = info[UIImagePickerController.InfoKey.mediaURL] as? URL else { return }
            let asset = AVAsset(url: url)
            guard let img = self.generateThumbnail(for: asset) else {
                print("Error: Thumbnail can be generated.")
                return
            }
            print("Image Size: \(img.size)")
            break
        default:
            break
        }
    }
}
于 2019-01-10T04:45:29.357 回答
2

对于斯威夫特 5

import AVKit

代码：

// Get Thumbnail Image from URL
fileprivate func getThumbnailFromUrl(_ url: String?, _ completion: @escaping ((_ image: UIImage?)->Void)) {

    guard let url = URL(string: url ?? "") else { return }
    DispatchQueue.main.async {
        let asset = AVAsset(url: url)
        let assetImgGenerate = AVAssetImageGenerator(asset: asset)
        assetImgGenerate.appliesPreferredTrackTransform = true

        let time = CMTimeMake(value: 2, timescale: 1)
        do {
            let img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
            let thumbnail = UIImage(cgImage: img)
            completion(thumbnail)
        } catch {
            print("Error :: ", error.localizedDescription)
            completion(nil)
        }
    }
}

用法 :: 取一个图像视图

@IBOutlet weak var imgThumbnail: UIImageView!

然后在以 URL为参数调用getThumbnailFromUrl缩略图的方法之后String

self.getThumbnailFromUrl(videoURL) { [weak self] (img) in

        guard let _ = self else { return }
        if let img = img {
            self?.imgThumbnail.image = img
        }
    }

请试试这个，如果它使用完整然后请评论 谢谢

于 2019-10-04T06:40:22.183 回答
1

也许这对面临同样问题的其他人很有用。我需要一个简单的解决方案来为图像、PDF 和视频创建缩略图。为了解决这个问题，我创建了以下库。

https://github.com/prine/ROThumbnailGenerator

用法非常简单： var thumbnailImage = ROThumbnail.getThumbnail(url)

它在内部具有三种不同的实现，并根据文件扩展名创建缩略图。如果您需要另一个文件扩展名的缩略图创建器，您可以轻松添加自己的实现。

于 2015-08-12T13:12:00.227 回答
1

Swift 2.1以所需的时间间隔获取缩略图

func getPreviewImageForVideoAtURL(videoURL: NSURL, atInterval: Int) -> UIImage? {
    print("Taking pic at \(atInterval) second")
    let asset = AVAsset(URL: videoURL)
    let assetImgGenerate = AVAssetImageGenerator(asset: asset)
    assetImgGenerate.appliesPreferredTrackTransform = true
    let time = CMTimeMakeWithSeconds(Float64(atInterval), 100)
    do {
        let img = try assetImgGenerate.copyCGImageAtTime(time, actualTime: nil)
        let frameImg = UIImage(CGImage: img)
        return frameImg
    } catch {
        /* error handling here */
    }
    return nil
}
于 2016-01-08T11:57:08.183 回答
0

当您将“fileURLWithPath”更改为“URLWithString”时，您将从 URL 获取缩略图。

就我而言，它是这样工作的。

NSURL *url = [NSURL URLWithString:filepath];
AVAsset *asset = [AVAsset assetWithURL:url];
AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];
CMTime time = [asset duration];
time.value = 0;
CGImageRef imageRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:NULL];
UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

return thumbnail;
于 2016-09-04T06:44:55.320 回答