如何从视频中读取帧作为UWP中的位图 [英] How to read frames from a video as bitmaps in UWP

问题描述

可以在通用Windows应用程序中加载视频并从中提取单个帧（如图像）？

Is it possible to load a video and extract single frames from it (as images) in Universal Windows Applications?

推荐答案

可以在通用Windows应用程序中加载视频并从中提取单个帧（如图像）？

Is it possible to load a video and extract single frames from it (as images) in Universal Windows Applications?

您可以使用 MediaComposition.GetThumbnailAsync 从视频中获取图像流。然后，您可以使用 RandomAccessStream.CopyAsync 进行转换 IInputStream 至 InMemoryRandomAccessStream 。我们可以添加IRandomAccessStream来设置 BitmapSource.SetSource 。

You can use MediaComposition.GetThumbnailAsync to get an image stream from the video. Then you can use RandomAccessStream.CopyAsync to convert the IInputStream to InMemoryRandomAccessStream. We can add the IRandomAccessStream to set BitmapSource.SetSource.

例如：

private async void Button_Click(object sender, RoutedEventArgs e)
{
    FileOpenPicker openPicker = new FileOpenPicker();
    foreach (string extension in FileExtensions.Video)
    {
        openPicker.FileTypeFilter.Add(extension);
    }
    StorageFile file = await openPicker.PickSingleFileAsync();
    var thumbnail = await GetThumbnailAsync(file);
    BitmapImage bitmapImage = new BitmapImage();
    InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
    await RandomAccessStream.CopyAsync(thumbnail, randomAccessStream);
    randomAccessStream.Seek(0);
    bitmapImage.SetSource(randomAccessStream);
    MyImage.Source = bitmapImage;
}

public async Task<IInputStream> GetThumbnailAsync(StorageFile file)
{
    var mediaClip = await MediaClip.CreateFromFileAsync(file);
    var mediaComposition = new MediaComposition();
    mediaComposition.Clips.Add(mediaClip);
    return await mediaComposition.GetThumbnailAsync(
        TimeSpan.FromMilliseconds(5000), 0, 0, VideoFramePrecision.NearestFrame);
}

internal class FileExtensions
{
    public static readonly string[] Video = new string[] { ".mp4", ".wmv" };
}

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