VideoCache #uwp #uwpdev

Earlier today (10 mins ago), we were discussing looping animated previews (rolling video frames) for articles and that maybe we should create a cache to prevent it being downloaded over and over again.

Back in UWP Community Toolkit, we created a CacheBase – a generic base implementation of Cache. This can be used to create just about any type of data cache.

This CacheBase was then used to implement ImageCache and finally FileCache just to show it can be done with other types too. So this is what I did.

public class VideoCache : CacheBase<MediaSource>
{
    /// <summary>
    /// Private singleton field.
    /// </summary>
    private static VideoCache _instance;

    /// <summary>
    /// Gets public singleton property.
    /// </summary>
    public static VideoCache Instance => _instance ?? (_instance = new VideoCache() { MaintainContext = true });

    protected override Task<MediaSource> InitializeTypeAsync(StorageFile baseFile)
    {
        return Task.Run(() => MediaSource.CreateFromStorageFile(baseFile));
    }

    protected override Task<MediaSource> InitializeTypeAsync(IRandomAccessStream stream)
    {
        return Task.Run(() => MediaSource.CreateFromStream(stream, "video/mp4"));
    }
}

Previously in my video player (see my previous blog post), I created a MediaSource from Uri.. now this to use the Cache

//MediaSource mediaSource = MediaSource.CreateFromUri(this.Video.Uri);
MediaSource mediaSource = await VideoCache.Instance.GetFromCacheAsync(this.Video.Uri);

Now the animated previews are not only cached and reused but they are also available offline.

To ensure that you do not build a large set, always make sure you set CacheDuration and remove expired items.

// somewhere in your App.xaml.cs
VideoCache.Instance.CacheDuration = TimeSpan.FromDays(1);

elsewhere in your cleanup code

await VideoCache.Instance.RemoveExpiredAsync();

Took me about 2 mins to roll out and get it running.

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