如何在iOS中从ALAsset获取视频的缩略图？

Question

如何在iOS中从ALAsset获取视频的缩略图？

iosobjective-cavplayeralassetslibrarycmtime

5

我希望能够从视频中获取每一帧的缩略图，并将这些图片保存在可变图片数组中。

我想使用这些图片作为动画播放。

NSURL* assetURL = [self.asset valueForProperty:ALAssetPropertyAssetURL];
NSDictionary* assetOptions = nil;

AVAsset* myAsset = [[AVURLAsset alloc] initWithURL:assetURL options:assetOptions];

self.imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:myAsset];


int duration = CMTimeGetSeconds([myAsset duration]);

for(int i = 0; i<duration; i++)
{
    CGImageRef imgRef = [self.imageGenerator copyCGImageAtTime:CMTimeMake(i, duration) actualTime:NULL error:nil];
    UIImage* thumbnail = [[UIImage alloc] initWithCGImage:imgRef scale:UIViewContentModeScaleAspectFit orientation:UIImageOrientationUp];
    [thumbnailImages addObject:thumbnail];
}

我正在使用以上代码来获取缩略图，但问题是如果有一个2秒的视频，我只会得到2个缩略图，但我想要20个缩略图（每秒10个缩略图）。

那么，如何使用CMTimeMake在每0.1秒获取一次缩略图呢？

- Lalit Kumar

4个回答

1

@Kirit Modi的解决方案使用Swift 3，需要进行一些小修改:

func generateThumbImage(url : URL) -> UIImage?{

  let asset = AVAsset(url: url)
  let assetImgGenerate : AVAssetImageGenerator = AVAssetImageGenerator(asset: asset)
assetImgGenerate.appliesPreferredTrackTransform = true
  let time = CMTimeMake(1, 30)
  let img = try? assetImgGenerate.copyCGImage(at: time, actualTime: nil)

  guard let cgImage = img else { return nil }

  let frameImg    = UIImage(cgImage: cgImage)
  return frameImg
}

- YYamil

0

extension UIImageView{
func getImageThumnail(forLink link: String) {
    let asset = AVAsset(url: URL(string: link)!)
    let assetImgGenerate = AVAssetImageGenerator(asset: asset)
    assetImgGenerate.appliesPreferredTrackTransform = true
    let time = CMTimeMakeWithSeconds(Float64(50), 100)
    DispatchQueue.global(qos: .userInteractive).async {
      do {
            let img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
            let thumbnail = UIImage(cgImage: img)
            DispatchQueue.main.async {
                self.image = thumbnail
            }
    } catch {
    }
    }
}
}

- Nex Mishra

0

以下代码用于从视频中获取时间为0.41的缩略图

NSString *str = [[self.videoArray objectAtIndex:i] valueForKey:@"vName"];
NSURL *videoURL = [NSURL URLWithString:str] ;
MPMoviePlayerController *player = [[[MPMoviePlayerController alloc] initWithContentURL:videoURL]autorelease];
UIImage  *thumbnail = [player thumbnailImageAtTime:0.41 timeOption:MPMovieTimeOptionNearestKeyFrame];
player = nil;

- Nimit Parekh

我想要从资产（视频类型）中获取所有缩略图图像，而不是单个图像。 - Kumar

您需要更改thumbnailImageAtTime:0.41的值。 - Nimit Parekh

我也在尝试你的代码。但是我正在使用ALAsset。所以，你能否根据ALAsset编辑你的答案。 - Kumar

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Kirit Modi · Accepted Answer

参考网站上的代码格式: 从视频中获取缩略图

Objective-C

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

    AVAsset *asset = [AVAsset assetWithURL:url];
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc]initWithAsset:asset];
self.imageGenerator.appliesPreferredTrackTransform = YES; 
        CMTime time = [asset duration];
        time.value = 0;
        Float duration = CMTimeGetSeconds([myAsset duration]);
   for(Float i = 0.0; i<duration; i=i+0.1)
    {
     CGImageRef imgRef = [self.imageGenerator copyCGImageAtTime:CMTimeMake(i, duration) actualTime:NULL error:nil];
     UIImage* thumbnail = [[UIImage alloc] initWithCGImage:imgRef scale:UIViewContentModeScaleAspectFit orientation:UIImageOrientationUp];
    [thumbnailImages addObject:thumbnail];
    }
}

Swift

func generateThumbImage(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
    }