C# Silverlight MediaElement wont play mp3 from web - silverlight

Question

Hi Ive been pulling my hair out over this for the last couple of days, I have a mediaelement in a Silverlight App written in C#
Im trying to stream an MP3 over http and play it through the silverlight app. Although it keeps catching an exception that says
AG_E_NETWORK_ERROR
The mp3 will not play and the MediaElement.MediaOpened event never fires
After searching on the net it appears this error is due to a curropt source but the mp3 plays fine when I point a webbrowser at the mp3.
heres the code
private void button1_Click(object sender, RoutedEventArgs e)
{
Uri source = new Uri("http://www.sm-testing.co.uk/mixes/youdontknow.mp3");
mediaElement1.Source = source;
mediaElement1.MediaFailed += new EventHandler<ExceptionRoutedEventArgs>(mediaElement1_MediaFailed);
mediaElement1.MediaOpened +=new RoutedEventHandler(mediaElement1_MediaOpened);
}
void mediaElement1_MediaFailed(object sender, ExceptionRoutedEventArgs e)
{
MessageBox.Show( e.ErrorException.ToString());
}
private void mediaElement1_MediaOpened(object sender, RoutedEventArgs e)
{
mediaElement1.Play();
}

Answer 1

I see you have used an actual URL in your example. I checked your site and there is no http://www.sm-testing.co.uk/ClientAccessPolicy.xml file or http://www.sm-testing.co.uk/crossdomain.xml file.
Without either of those files (preferably ClientAccessPolicy.xml as the other is an old Flash compatibility format and missing some features) Silverlight will only retrieve files from the domain it is hosted on. This is a security feature to stop Silverlight app taking data or images from just anywhere without permission.
Example ClientAccessPolicy.xml below allows any access to any http or https request:
<?xml version="1.0" encoding="utf-8"?>
<access-policy>
<cross-domain-access>
<policy>
<allow-from http-request-headers="*">
<domain uri="http://*" />
<domain uri="https://*" />
</allow-from>
<grant-to>
<resource path="/" include-subpaths="true"/>
</grant-to>
</policy>
</cross-domain-access>
</access-policy>
You don't need a crossdomain.xml as well unless you want to open up access to Flash apps too :)