Capture, scale and crop to get portrait 640x1136 photo

        private async Task<StorageFile> CaptureImage()
        {
            var stream = new InMemoryRandomAccessStream();
            await Viewfinder.CapturePhotoToStreamAsync(stream, ImageEncodingProperties.CreateJpeg());

            var decoder = await BitmapDecoder.CreateAsync(stream);

            var scale = (double)1136 / (double)decoder.PixelWidth;

            var scaledHeight = (uint)(decoder.PixelWidth * 9 / 16);
            var startPointY = (uint)((decoder.PixelHeight - scaledHeight) / 2);

            var bounds = new BitmapBounds();
            bounds.X = 0;
            bounds.Y = (uint)Math.Floor((double)(startPointY * scale));
            bounds.Height = 640;
            bounds.Width = 1136;

            var photoStorage = await ApplicationData.Current.LocalFolder.CreateFileAsync("image.jpg", CreationCollisionOption.ReplaceExisting);
            var outputStream = await photoStorage.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

            outputStream.Size = 0;


            var encoder = await BitmapEncoder.CreateForTranscodingAsync(outputStream, decoder);
            encoder.BitmapTransform.Bounds = bounds;
            encoder.BitmapTransform.ScaledHeight = (uint)Math.Floor((double)(decoder.PixelHeight * scale));
            encoder.BitmapTransform.ScaledWidth = (uint)Math.Floor((double)(decoder.PixelWidth * scale));

            var rotation = App.ViewModel.VideoLocation == Windows.Devices.Enumeration.Panel.Back ? PhotoOrientation.Rotate270 : PhotoOrientation.Rotate90;
            var properties = new BitmapPropertySet();
            properties.Add("System.Photo.Orientation", new BitmapTypedValue(rotation, PropertyType.UInt16));

            await encoder.BitmapProperties.SetPropertiesAsync(properties);

            await encoder.FlushAsync();

            outputStream.Dispose();

            return photoStorage;
        }