async public void ChangeSource()
        {
            var openPicker = new Windows.Storage.Pickers.FileOpenPicker();

            openPicker.FileTypeFilter.Add(".wmv");
            openPicker.FileTypeFilter.Add(".mp4");
            openPicker.FileTypeFilter.Add(".wma");
            openPicker.FileTypeFilter.Add(".mp3");

            file = await openPicker.PickSingleFileAsync();

            openPicker.ViewMode = PickerViewMode.Thumbnail;
            openPicker.SuggestedStartLocation = PickerLocationId.Desktop;


            // video1 is a MediaElement defined in XAML
            if (null != file)
            {
                var stream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

                Video1.SetSource(stream, file.ContentType);
                Songinfo.Text = file.DisplayName;
                Video1.Play();
            }
        }
        private async void NextSong()
        {
            x++;
            var file = playlist[x];

            if (file == null)
            {
                x    = 0;
                file = playlist[x];
                var properties = await file.Properties.GetMusicPropertiesAsync();

                if (file != null)
                {
                    var stream = await file.OpenAsync(FileAccessMode.Read);

                    Songinfo.Text = file.DisplayName;
                    // mediaControl is a MediaElement defined in XAML
                    Video1.SetSource(stream, file.ContentType);
                }
            }
            else
            {
                var properties = await file.Properties.GetMusicPropertiesAsync();

                if (file != null)
                {
                    var stream = await file.OpenAsync(FileAccessMode.Read);

                    Songinfo.Text = file.DisplayName;
                    // mediaControl is a MediaElement defined in XAML
                    Video1.SetSource(stream, file.ContentType);
                }
            }
        }
        async private void Previous1Song_Click(object sender, RoutedEventArgs e)
        {
            x--;
            if (x < 0)
            {
                x = 0;
                var file       = playlist[x];
                var properties = await file.Properties.GetMusicPropertiesAsync();

                if (file != null)
                {
                    var stream = await file.OpenAsync(FileAccessMode.Read);

                    Songinfo.Text = file.DisplayName;
                    // mediaControl is a MediaElement defined in XAML
                    Video1.SetSource(stream, file.ContentType);
                }
            }
            else
            {
                var file       = playlist[x];
                var properties = await file.Properties.GetMusicPropertiesAsync();

                if (file != null)
                {
                    var stream = await file.OpenAsync(FileAccessMode.Read);

                    Songinfo.Text = file.DisplayName;
                    // mediaControl is a MediaElement defined in XAML
                    Video1.SetSource(stream, file.ContentType);
                }
            }
        }
        async private void AddSong_Click(object sender, RoutedEventArgs e)
        {
            var openPicker = new Windows.Storage.Pickers.FileOpenPicker();

            openPicker.FileTypeFilter.Add(".wmv");
            openPicker.FileTypeFilter.Add(".mp4");
            openPicker.FileTypeFilter.Add(".wma");
            openPicker.FileTypeFilter.Add(".mp3");

            StorageFile file = await openPicker.PickSingleFileAsync();

            openPicker.ViewMode = PickerViewMode.Thumbnail;
            openPicker.SuggestedStartLocation = PickerLocationId.Desktop;


            // video1 is a MediaElement defined in XAML
            if (null != file)
            {
                var stream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

                playlist[i] = file;
                int b = i + 1;
                PlaylistSongs.Text += "\n" + b.ToString() + ") " + playlist[i].DisplayName;
                Songinfo.Text       = file.DisplayName;
                // mediaControl is a MediaElement defined in XAML
                Video1.SetSource(stream, file.ContentType);
                i++;
            }
        }
        async public void ChangeSource()
        {
            var openPicker = new Windows.Storage.Pickers.FileOpenPicker();

            openPicker.FileTypeFilter.Add(".wmv");
            openPicker.FileTypeFilter.Add(".mp4");
            openPicker.FileTypeFilter.Add(".wma");
            openPicker.FileTypeFilter.Add(".mp3");

            //file = await openPicker.PickSingleFileAsync();
            openPicker.ViewMode = PickerViewMode.Thumbnail;
            openPicker.SuggestedStartLocation = PickerLocationId.Desktop;


            var files = await openPicker.PickMultipleFilesAsync();

            if (files.Count > 0)
            {
                // Application now has read/write access to the picked file(s)
                foreach (Windows.Storage.StorageFile file1 in files)
                {
                    var stream = await file1.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);

                    Video1.SetSource(stream, file1.ContentType);
                    playlist[i]   = file1;
                    Songinfo.Text = file1.DisplayName;
                    int n = i + 1;
                    PlaylistSongs.Text += "\n" + n.ToString() + ") " + playlist[i].DisplayName;
                    i++;
                }
            }
            else
            {
                Songinfo.Text = "Operation cancelled.";
            }

            // video1 is a MediaElement defined in XAML
            //if (null != file)
            //{
            //    var stream = await file.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
            //    Video1.SetSource(stream, file.ContentType);
            //    playlist[i] = file;
            //    Songinfo.Text = file.DisplayName;
            //    PlaylistSongs.Text += "\n" + "1" + ") " + playlist[i].DisplayName;
            //    i++;
            //    Video1.Play();
            //}
        }