相关疑难解决方法(0)

我试图从iphone 3GS相机拍摄的视频中获取(第一帧的)缩略图,以便我可以显示它.这该怎么做？

我正在尝试使用MPMoviePlayerController从选定的视频文件中提取多个图像.以下是我编写的代码.

movie = [[MPMoviePlayerController alloc] initWithContentURL:[info  objectForKey:UIImagePickerControllerMediaURL]];

NSNumber *time1 = [NSNumber numberWithInt:1];
NSNumber *time2 = [NSNumber numberWithInt:3];
NSNumber *time3 = [NSNumber numberWithInt:5];

NSArray *times = [NSArray arrayWithObjects:time1,time2,time3,nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleThumbnailImageRequestFinishNotification:) name:MPMoviePlayerThumbnailImageRequestDidFinishNotification object:movie];

[movie requestThumbnailImagesAtTimes:times timeOption:MPMovieTimeOptionExact];

这是通知的处理程序

  -(void)handleThumbnailImageRequestFinishNotification:(NSNotification*)note
  {
     NSDictionary *userinfo = [note userInfo];
     NSError* value = [userinfo objectForKey:MPMoviePlayerThumbnailErrorKey];

     if (value!=nil)
     {
       NSLog(@"Error: %@", [value debugDescription]);
     }
     else
     {
       _imageView.image = [userinfo valueForKey:MPMoviePlayerThumbnailImageKey];
     }
  }

但是,我收到以下错误消息:

  Error: Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed" UserInfo=0x1d8a63d0 {NSLocalizedDescription=The operation could …