Binding Source in MediaTimeline - wpf

Question

I am trying to have the mediatimeline bind to a Uri like so:
<UserControl.Resources>
<Storyboard x:Key="myStoryboard">
<MediaTimeline Storyboard.TargetName="myMediaPlayer"
Source="{Binding MediaSource}"
RepeatBehavior="Forever" />
</Storyboard>
</UserControl.Resources>
<UserControl.Triggers>
<EventTrigger RoutedEvent="FrameworkElement.Loaded">
<BeginStoryboard Storyboard="{StaticResource myStoryboard}" />
</EventTrigger>
</UserControl.Triggers>
<Grid>
<MediaElement x:Name="mymediaPlayer" />
</Grid>
However, when I do this, it says that I need to "Must Specify URI." Dispatcher exception. In the viewmodel, I have a property like:
public Uri MediaSource
{
get { return _mediaSource; }
set
{
if (_oscilloscopeSource != value)
{
_mediaSource= value;
OnPropertyChanged("MediaSource");
}
}
}
It seems as though when the media player is loaded, it doesn't read the source from the binding. What gives?
In the constructor, I have:
_mediaSource = new Uri(#"C:\someMovie.mov", UriKind.Absolute);
Thanks.

Answer 1

Update
Can't get this to work so shooting in the dark now. Does moving the trigger to MediaElement make a difference?
<MediaElement x:Name="myMediaPlayer">
<MediaElement.Triggers>
<EventTrigger RoutedEvent="FrameworkElement.Loaded">
<BeginStoryboard Storyboard="{StaticResource myStoryboard}" />
</EventTrigger>
</MediaElement.Triggers>
</MediaElement>
I tried this out and it works for me. Possible reasons I can think of.
Do you have the DataContext set for the UserControl?
Setting _mediaSource directly won't call OnPropertyChanged since you're not setting the CLR property. Set MediaSource instead.
Your MediaElement is named mymediaPlayer and not myMediaPlayer as the TargetName. (Typo?)
Except for the MediaElement Name which I changed, my working xaml is identical to yours. This is my full code behind file
public partial class UserControl1 : UserControl, INotifyPropertyChanged
{
public UserControl1()
{
InitializeComponent();
MediaSource = new Uri("C:\\C1.MOV");
this.DataContext = this;
}
private Uri _mediaSource;
public Uri MediaSource
{
get
{
return _mediaSource;
}
set
{
_mediaSource = value;
OnPropertyChanged("MediaSource");
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}