Question

从我所读到的苹果不会公开api，允许开发人员使用当前的sdk获取电影的缩略图。

任何人都可以分享一些关于他们如何处理的代码吗？我听说你可以访问相机选择器视图，并在ui图像选择器关闭之前找到图像视图。这看起来有点难看。

我也考虑过使用ffmpeg从电影中抓取一个帧，但不知道如何将其编译为iphone的库。任何指针都将非常感激

Answer 1

希望我的代码可以帮助你们。它很丑。我认为苹果应该打开这种API。当然，应删除所有NSLog（）。这只是为了演示。

阿尔文

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
 // e.g.
 NSString *tempFilePath = [(NSURL *)[info valueForKey:UIImagePickerControllerMediaURL] absoluteString];
 NSLog(@"didFinishPickingMediaWithInfo: %@",tempFilePath);
 // e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp/capture/capturedvideo.MOV
 tempFilePath = [[tempFilePath substringFromIndex:16] retain];
 NSLog(@"didFinishPickingMediaWithInfo: %@",tempFilePath);
 NSLog(@"===Try to save video to camera roll.===");
 NSLog(@"UIVideoAtPathIsCompatibleWithSavedPhotosAlbum: %@",UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(tempFilePath)? @"YES":@"NO");
 // Check if the video file can be saved to camera roll.
    if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(tempFilePath)){
  // YES. Copy it to the camera roll.
  UISaveVideoAtPathToSavedPhotosAlbum(tempFilePath, self, @selector(video:didFinishSavingWithError:contextInfo:), tempFilePath);
 }

 [self dismissModalViewControllerAnimated:YES];
}

- (void)video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(NSString *)contextInfo{
 NSLog(@"didFinishSavingWithError--videoPath in camera roll:%@",videoPath);
 NSLog(@"didFinishSavingWithError--videoPath in temp directory:%@",contextInfo);
 // The thumbnail jpg should located in this directory.
 NSString *thumbnailDirectory = [[contextInfo stringByDeletingLastPathComponent] stringByDeletingLastPathComponent];

 // Debug info. list all files in the directory of the video file.
 // e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp/capture
 NSLog([contextInfo stringByDeletingLastPathComponent]);
 NSLog([[[NSFileManager defaultManager] contentsOfDirectoryAtPath:[contextInfo stringByDeletingLastPathComponent] error:nil] description]);
 // Debug info. list all files in the parent directory of the video file, i.e. the "~/tmp" directory.
 // e.g. /private/var/mobile/Applications/D1E784A4-EC1A-402B-81BF-F36D3A08A332/tmp
 NSLog(thumbnailDirectory);
 NSLog([[[NSFileManager defaultManager] contentsOfDirectoryAtPath:thumbnailDirectory error:nil] description]);
 ///////////////////

 // Find the thumbnail for the video just recorded.
 NSString *file,*latestFile;
 NSDate *latestDate = [NSDate distantPast];
 NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:[[contextInfo stringByDeletingLastPathComponent]stringByDeletingLastPathComponent]];
 // Enumerate all files in the ~/tmp directory
 while (file = [dirEnum nextObject]) {
  // Only check files with jpg extension.
  if ([[file pathExtension] isEqualToString: @"jpg"]) {
   NSLog(@"***latestDate:%@",latestDate);
   NSLog(@"***file name:%@",file);
   NSLog(@"***NSFileSize:%@", [[dirEnum fileAttributes] valueForKey:@"NSFileSize"]);
   NSLog(@"***NSFileModificationDate:%@", [[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"]);
   // Check if current jpg file is the latest one.
   if ([(NSDate *)[[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"] compare:latestDate] == NSOrderedDescending){
    latestDate = [[dirEnum fileAttributes] valueForKey:@"NSFileModificationDate"];
    latestFile = file;
    NSLog(@"***latestFile changed:%@",latestFile);
   }
  }
 }
 // The thumbnail path.
 latestFile = [NSTemporaryDirectory() stringByAppendingPathComponent:latestFile];
 NSLog(@"****** The thumbnail file should be this one:%@",latestFile);

 // Your code ...
 // Your code ...
 // Your code ...
}

Answer 2

在与缩略图的电影相同的文件夹中有一个jpg。我只用手机录制的视频测试过，但效果很好。它的名字与电影的名称不同，因此请获取电影所在的目录路径并迭代.jpg并离开。

Answer 3

我发现的最佳方法... MPMoviePlayerController thumbnailImageAtTime：timeOption

Answer 4

NSString *videoLink=[info objectForKey:@"UIImagePickerControllerMediaURL"];

MPMoviePlayerController *player = [[MPMoviePlayerController alloc] initWithContentURL:(NSURL*)videoLink];
UIImage *imageSel = [player thumbnailImageAtTime:1.0 timeOption:MPMovieTimeOptionNearestKeyFrame];
[player stop];
[player release];

Answer 5

这是一篇关于使用ffmpeg从电影中提取帧的博文：

http://www.codza.com/extracting-frames-from-movies-on-iphone

github上的相应项目：iFrameExtractor

Answer 6

只想提供此更新。当您将选择器设置为UIImagePickerControllerSourceTypeCamera时，在获取缩略图方面似乎有用。但是，当您尝试从现有库中选择时（即UIImagePickerControllerSourceTypePhotoLibrary）缩略图的.jpg永远不会被创建。我甚至尝试用UISaveVideoAtPathToSavedPhotosAlbum（...）重新保存，但仍然没有骰子。看起来像是在捕获视频时首先创建缩略图。这是你“抓住”它的唯一机会。之后它会被移动到/ var / mobile / Media / DCIM /的子目录中。虽然您实际上可以列出缩略图并看到它存在，但该文件是不可读和不可复制的，因为我认为目录受到保护。

如果有人有解决方法，我会非常感谢，因为在我的情况下，我需要从库中选择现有视频的缩略图。

Answer 7

如果您使用UIImagePickerController获取图像，那么JPG将不会存储在tmp目录中。我不确定这个问题的答案，但是ffmpeg，更具体地说是它背后的库，可能是你的选择。

iphone sdk＆gt; 3.0。视频缩略图？

7 个答案: