从 iPhone SDK 中的视频 url 创建缩略图

Question

我正在尝试从视频网址获取缩略图。 视频是 m3u8 格式的流 (HLS)。 我已经尝试过 MPMoviePlayerController 中的 requestThumbnailImagesAtTimes，但这没有用。 有没有人有解决这个问题的方法？ 如果有，你是怎么做的？

Answer 1

如果你不想使用MPMoviePlayerController ，你可以这样做：

    AVAsset *asset = [AVAsset assetWithURL:sourceURL];
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];
    CMTime time = CMTimeMake(1, 1);
    CGImageRef imageRef = [imageGenerator copyCGImageAtTime:time actualTime:NULL error:NULL];
    UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);  // CGImageRef won't be released by ARC

这是 Swift 中的一个示例：

func thumbnail(sourceURL sourceURL:NSURL) -> UIImage {
    let asset = AVAsset(URL: sourceURL)
    let imageGenerator = AVAssetImageGenerator(asset: asset)
    let time = CMTime(seconds: 1, preferredTimescale: 1)

    do {
        let imageRef = try imageGenerator.copyCGImageAtTime(time, actualTime: nil)
        return UIImage(CGImage: imageRef)
    } catch {
        print(error)
        return UIImage(named: "some generic thumbnail")!
    }
}

我更喜欢使用AVAssetImageGenerator不是MPMoviePlayerController因为它是线程安全的，并且一次可以实例化多个。

Answer 2

从视频网址获取缩略图。

    NSString *strVideoURL = @"http://www.xyzvideourl.com/samplevideourl";
    NSURL *videoURL = [NSURL URLWithString:strVideoURL] ;
    MPMoviePlayerController *player = [[[MPMoviePlayerController alloc] initWithContentURL:videoURL]autorelease];
    UIImage  *thumbnail = [player thumbnailImageAtTime:1.0 timeOption:MPMovieTimeOptionNearestKeyFrame];
    player = nil;

用strVideoURL替换您的视频 URL 字符串。 您将获得缩略图作为video的输出。 缩略图是UIImage类型的数据！

Answer 3

-(UIImage *)loadThumbNail:(NSURL *)urlVideo
{    
    AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:urlVideo options:nil];
    AVAssetImageGenerator *generate = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    generate.appliesPreferredTrackTransform=TRUE;
    NSError *err = NULL;
    CMTime time = CMTimeMake(1, 60);
    CGImageRef imgRef = [generate copyCGImageAtTime:time actualTime:NULL error:&err];
    NSLog(@"err==%@, imageRef==%@", err, imgRef);
    return [[UIImage alloc] initWithCGImage:imgRef];
}

在您的项目中添加AVFoundation框架，不要忘记导入<AVFoundation/AVFoundation.h>并且您必须将保存在文档目录中的视频路径作为参数传递，并以UIImage接收图像。

Answer 4

您可以使用以下代码从您的视频网址获取缩略图

MPMoviePlayerController *player = [[[MPMoviePlayerController alloc] initWithContentURL:videoURL]autorelease];
UIImage  *thumbnail = [player thumbnailImageAtTime:0.0 timeOption:MPMovieTimeOptionNearestKeyFrame];

Answer 5

也许这对面临同样问题的其他人有用。 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（在 Swift 中）。

https://github.com/prine/ROThumbnailGenerator

用法很简单：varthumbnailImage = 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者，您可以轻松添加自己的实现。

Answer 6

斯威夫特 3 版本：

func createThumbnailOfVideoFromFileURL(videoURL: String) -> UIImage? {
    let asset = AVAsset(url: URL(string: videoURL)!)
    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 {
        // Set a default image if Image is not acquired
        return UIImage(named: "ico_placeholder")
    }
}

Answer 7

对于 Swift 3.0：

  func generateThumbnailForVideoAtURL(filePathLocal: NSString) -> UIImage? {
    let vidURL = NSURL(fileURLWithPath:filePathLocal as String)
    let asset = AVURLAsset(url: vidURL as URL)
    let generator = AVAssetImageGenerator(asset: asset)
    generator.appliesPreferredTrackTransform = true

    let timestamp = CMTime(seconds: 1, preferredTimescale: 60)

    do {
        let imageRef = try generator.copyCGImage(at: timestamp, actualTime: nil)
        let frameImg    : UIImage = UIImage(cgImage: imageRef)
        return frameImg
    } catch let error as NSError {
        print("Image generation failed with error ::\(error)")
        return nil
    }
}

Answer 8

对于Swift 5，您可以通过以下方式获得：

首先import AVKit or AVFoundation到ViewController

import AVKit

代码：

// Get Thumbnail Image from URL
private 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

@IBOutlet weak imgThumbnail: ImageView! 

然后调用getThumbnailFromUrl方法并将URL作为Sting传递

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

    guard let `self` = self else { return }

    if let img = img {
        self.imgThumbnail.image = img
    }
}

谢谢

Answer 9

带有 AVAssetImageGenerator 的 Swift 2 代码：

func thumbnailImageForVideo(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
    }
}