检索StorageFile（视频）的缩略图是位于WP8.1应用的localfolder [英] Retrieving thumbnail of a StorageFile (Video) which is located in the localfolder of the app in WP8.1

问题描述

我试图让位于应用程序的应用程序包（LocalFolder）内StorageFile的缩略图。存储文件是一个媒体文件可以是图片（JPG或PNG）或视频（MP4或WMV）。现在，当我尝试使用StorageFile类我得到一个

的System.Exception的GetThumbnailAsync（ThumbnailMode）方法来获得缩略图：该组件不能被发现。

错误，而同样的事情，工作正常，如果该文件是图像或视频这不是应用程序包内。下面是我使用

  StorageFile文件代码隐藏; 
私人异步无效BtnGetVideo_Click（对象发件人，RoutedEventArgs E）
 {
 StorageFolder文件夹=等待Windows.ApplicationModel.Package.Current.InstalledLocation.GetFolderAsync（Assets\\TestImgs）; 
档=等待folder.GetFileAsync（SMTest.mp4）; 
} 
 
私人异步无效BtnGetThumb_Click（对象发件人，RoutedEventArgs E）
 {
如果（文件！= NULL）
 {
的BitmapImage图像=新的BitmapImage（）; 
 image.SetSource（等待file.GetThumbnailAsync（ThumbnailMode.VideosView））; 
 ImagePreview.Source =图像; 
} 
} 
  

和这里是XAML吧

 < StackPanel中的Horizo​​ntalAlignment =中心VerticalAlignment =中心> 
<按钮X：NAME =BtnGetVideoCONTENT =获取本地视频点击=BtnGetVideo_Click/> 
<按钮X：NAME =BtnGetThumbCONTENT =获取缩略图点击=BtnGetThumb_Click/> 
<图像X：NAME =ImagePreviewHEIGHT =200/> 
< / StackPanel的> 
  

解决方案

我知道它的一个老问题，但它会帮助任何人仍在寻找解决方案。

下面是我能够一3小时斗争后成功运行的代码，它的工作。

 使用（videoFrameReader videoFrameReader =新videoFrameReader（newCreatedVideo））
 {
等待videoFrameReader.OpenMF（）; 
 VAR图像= videoFrameReader.GetFrameAsBitmap（TimeSpan.FromSeconds（0））; 
 
 videoFrameReader.Finalize（）; 
} 
  

I'm trying to get the thumbnail of the StorageFile located inside the application package (LocalFolder) of the app. The storage file is a media file which can be image(jpg or png) or a video (mp4 or wmv). Now when i try to get the thumbnail using GetThumbnailAsync(ThumbnailMode) method of the StorageFile class i get a

System.Exception : The component cannot be found.

error, while the same thing works fine if the file is image or a video which is not inside the app package. Here is the codebehind i'm using

    StorageFile file;
    private async void BtnGetVideo_Click(object sender, RoutedEventArgs e)
    {
        StorageFolder folder = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFolderAsync("Assets\\TestImgs");
        file = await folder.GetFileAsync("SMTest.mp4");
    }

    private async void BtnGetThumb_Click(object sender, RoutedEventArgs e)
    {
        if (file != null)
        {
            BitmapImage image = new BitmapImage();
            image.SetSource(await file.GetThumbnailAsync(ThumbnailMode.VideosView));
            ImagePreview.Source = image;
        }
    }

and here is the xaml for it

        <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
            <Button x:Name="BtnGetVideo" Content="Get a Local Video" Click="BtnGetVideo_Click"/>
            <Button x:Name="BtnGetThumb" Content="Get Thumbnails" Click="BtnGetThumb_Click"/>
            <Image x:Name="ImagePreview" Height="200"/>
        </StackPanel>

解决方案

I know its an old problem, but it will help anyone still searching for solution.

Below is the code I am able to run successfully after a 3 hours of struggle, and its working.

using (VideoFrameReader videoFrameReader = new VideoFrameReader(newCreatedVideo))
        {
            await videoFrameReader.OpenMF();
            var image = videoFrameReader.GetFrameAsBitmap(TimeSpan.FromSeconds(0));

            videoFrameReader.Finalize();
        }

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