从iPhone SDK中的视频URL创建缩略图

Question

我正在尝试从视频URL获取缩略图。视频是m3u8格式的流（HLS）。我已经从MPMoviePlayerController尝试了requestThumbnailImagesAtTimes，但是没有用。有谁能解决这个问题？如果是这样，您怎么做？

Answer 1

如果您不想使用MPMoviePlayerController，则可以执行此操作：

    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而不是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替换视频URL字符串。您将从video中获得缩略图作为输出。缩略图是UIImage类型数据！

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>，您必须将保存在文档目录中的视频的路径作为参数传递，并将图像作为UIImage接收。

Answer 4

您可以使用以下代码从视频网址中获取缩略图

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

Answer 5

也许这对面临相同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。为了解决该问题，我创建了以下库（在Swift中）。

https://github.com/prine/ROThumbnailGenerator

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

它内部具有三种不同的实现，并且根据文件扩展名的确会创建缩略图。如果需要其他文件扩展名的缩略图创建者，则可以轻松添加自己的实现。

Answer 6

Swift 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

使用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
    }
}

Answer 9

对于Swift 5，您可以通过以下方式获取它：

第一个import AVKit or AVFoundation至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