Problem definition

• MediaPlayer.Position is int value, but Progressbar.Progress is double value (0 to 1.0)
• Need duration to convert

Create a custom Converter

Implements Xamarin.Forms.IValueConverter

public class PositionToProgressConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return ((int)value / (double)(GetParameter(parameter)));
    }
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (int)((double)value * GetParameter(parameter));
    }
    int GetParameter(object parameter)
    {
        var duration = ((Tizen.TV.UIControls.Forms.MediaPlayer)parameter).Duration;
        if (duration == 0)
            duration = 1;
        return duration;
    }
}

Pass a MediaPlayer instance as the parameter

Use custom converter in Xaml

....

    <ContentPage.Resources>
        <ResourceDictionary>
            <local:PositionToProgressConverter x:Key="positionToProgress"/>
        </ResourceDictionary>
    </ContentPage.Resources>
...

    <ProgressBar Progress="{Binding Source={x:Reference Player}, Path=Position, Converter={StaticResource positionToProgress}, ConverterParameter={x:Reference Player}}}"/>

....