TimeSpan timeOfFrame = new TimeSpan(0, 0, 1);
//pick mp4 file
var picker = new Windows.Storage.Pickers.FileOpenPicker();
picker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.VideosLibrary;
picker.FileTypeFilter.Add(".mp4");
StorageFile pickedFile = await picker.PickSingleFileAsync();
if (pickedFile == null)
{
return;
}
///
//Get video resolution
List<string> encodingPropertiesToRetrieve = new List<string>();
encodingPropertiesToRetrieve.Add("System.Video.FrameHeight");
encodingPropertiesToRetrieve.Add("System.Video.FrameWidth");
IDictionary<string, object> encodingProperties = await pickedFile.Properties.RetrievePropertiesAsync(encodingPropertiesToRetrieve);
uint frameHeight = (uint)encodingProperties["System.Video.FrameHeight"];
uint frameWidth = (uint)encodingProperties["System.Video.FrameWidth"];
///
//Use Windows.Media.Editing to get ImageStream
var clip = await MediaClip.CreateFromFileAsync(pickedFile);
var composition = new MediaComposition();
composition.Clips.Add(clip);
var imageStream = await composition.GetThumbnailAsync(timeOfFrame, (int)frameWidth, (int)frameHeight, VideoFramePrecision.NearestFrame);
///
//generate bitmap
var writableBitmap = new WriteableBitmap((int)frameWidth, (int)frameHeight);
writableBitmap.SetSource(imageStream);
//generate some random name for file in PicturesLibrary
var saveAsTarget = await KnownFolders.PicturesLibrary.CreateFileAsync("IMG" + Guid.NewGuid().ToString().Substring(0, 4) + ".jpg");
//get stream from bitmap
Stream stream = writableBitmap.PixelBuffer.AsStream();
byte[] pixels = new byte[(uint)stream.Length];
await stream.ReadAsync(pixels, 0, pixels.Length);
using (var writeStream = await saveAsTarget.OpenAsync(FileAccessMode.ReadWrite))
{
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, writeStream);
encoder.SetPixelData(
BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Premultiplied,
(uint)writableBitmap.PixelWidth,
(uint)writableBitmap.PixelHeight,
96,
96,
pixels);
await encoder.FlushAsync();
using (var outputStream = writeStream.GetOutputStreamAt(0))
{
await outputStream.FlushAsync();
}
}