前言
iOS 中获取视频第一帧有两种方式
第一种：使用AVFoundation获取
将耗时的操作放在异步执行队列 dispatch_async，防止造成线程堵塞，刷新UI放在 主线程
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| - (UIImage *)getFirstFrameFromVideoWithUrl:(NSURL *)url{
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:url options:nil];
AVAssetImageGenerator *assetGennerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
assetGennerator.appliesPreferredTrackTransform = YES;
CMTime time = CMTimeMakeWithSeconds(0.0, 600);
CMTime actualTime;
NSError *error = nil;
CGImageRef image = [assetGennerator copyCGImageAtTime:time actualTime:&actualTime error:&error];
UIImage *videoImg = [[UIImage alloc] initWithCGImage:image];
CGImageRelease(image);
return videoImg;
}
|
第二种方式：使用SDWebImage获取，并缓存图片
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| - (void)method2{
NSURL *url = [NSURL URLWithString:@"https://klxxcdn.oss-cn-hangzhou.aliyuncs.com/histudy/hrm/media/bg1.mp4"];
NSString *urlKey = url.absoluteString;
// 先从缓存中查找是否有图片
SDImageCache *imgCache = [SDImageCache sharedImageCache];
UIImage *memoryImg = [imgCache imageFromCacheForKey:urlKey];
if (memoryImg) {
self.imgV.image = memoryImg;
}else {
// 从磁盘中查找是否有图片
UIImage *diskImg = [imgCache imageFromDiskCacheForKey:urlKey];
if (diskImg) {
self.imgV.image = diskImg;
}else { // 如果都不存在
// 开启异步线程下载图片
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:url options:nil];
NSParameterAssert(asset);
AVAssetImageGenerator *assetGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
assetGenerator.appliesPreferredTrackTransform = YES;
assetGenerator.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;
CGImageRef thumbImgRef = NULL;
CFTimeInterval thumbImgTime = 1;
NSError *thumbImgError = nil;
thumbImgRef = [assetGenerator copyCGImageAtTime:CMTimeMake(thumbImgTime, 60) actualTime:NULL error:&thumbImgError];
if (!thumbImgRef){
NSLog(@"thumbImgError:%@",thumbImgError);
}
UIImage *thumbImg = thumbImgRef ? [[UIImage alloc] initWithCGImage:thumbImgRef] : nil;
// 主线程显示UI
dispatch_async(dispatch_get_main_queue(), ^{
SDImageCache *imgCache = [SDImageCache sharedImageCache];
[imgCache storeImage:thumbImg forKey:urlKey completion:^{
NSLog(@"store Image success");
}];
self.imgV.image = thumbImg;
});
});
}
}
}
|
