iOS 获取视频截图 以及 CMTimeMakeWithSeconds 与 CMTimeMake的区别

//获取网络视频的缩略图

• (UIImage *)getThumbnailImageFromVideoURL:(NSURL *)URL time:(NSTimeInterval )videoTime{

  if (!URL) return nil;

  UIImage *shotImage;

  AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:URL options:nil];

  AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:asset];

  gen.appliesPreferredTrackTransform = YES;
  //videoTime 截视频中第几秒的屏
  CMTime time = CMTimeMakeWithSeconds(videoTime, 600);

  NSError *error = nil;

  CMTime actualTime;

  CGImageRef image = [gen copyCGImageAtTime:time actualTime:&actualTime error:&error];

  shotImage = [[UIImage alloc] initWithCGImage:image];

  CGImageRelease(image);

  return shotImage;
  }

//获取本地视频缩略图

• (UIImage *)getThumbnailImageFromFilePath:(NSString *)videoPath time:(NSTimeInterval )videoTime {

  if (!videoPath) {
  return nil;
  }
  AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:[[NSURL alloc] initFileURLWithPath:videoPath] options:nil];
  AVAssetImageGenerator *assetImageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
  assetImageGenerator.appliesPreferredTrackTransform = YES;
  assetImageGenerator.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;

  CGImageRef thumbnailImageRef = NULL;
  CFTimeInterval thumbnailImageTime = videoTime;
  thumbnailImageRef = [assetImageGenerator copyCGImageAtTime:CMTimeMake(thumbnailImageTime, 600)
  actualTime:NULL error:nil];
  if (!thumbnailImageRef) {
  return nil;
  }

  UIImage *thumbnailImage = [[UIImage alloc] initWithCGImage:thumbnailImageRef];

  CFRelease(thumbnailImageRef);

  return thumbnailImage;

}

摘抄自：https://www.jianshu.com/p/6b6ffe0e4981
测试视频地址：http://static.tripbe.com/videofiles/20121214/9533522808.f4v.mp4