Silverlight / WPF - Problem with media player in xaml

Hello

Is the sound file in or outside of the xap?  Try a local test of the sound file in a new project. 

Sound file in XAP:
XAML: 

<MediaElement x:Name="media" Source="Kalimba.mp3" />

Sound file not in XAP (relative path to XAP):
XAML: 

<MediaElement x:Name="media" />

C#: 

media.Source = new Uri("Kalimba.mp3", UriKind.Relative);

Sound file not in XAP (Webclient approach):

public partial class MainPage : UserControl
{
    public MainPage()
    {
        InitializeComponent();

        WebClient client = new WebClient();
        client.OpenReadCompleted += new OpenReadCompletedEventHandler(webClient_OpenReadCompleted);
        client.OpenReadAsync(new Uri("Kalimba.mp3", UriKind.Relative));
    }

    void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
    {
        if (e.Error == null)
            media.SetSource(e.Result);
    }
}

Hope this helpful

Hello

The local file won't work in a normal Silverlight application because of Silverlights "sanboxed" security model.

Running a normal Silverlight application in your browser, you can't access local resources like you can if you were running an installed winforms/WPF application.

Have a look at this video tutorial http://www.silverlight.net/learn/videos/all/local-file-access/, if you want to learn more about accessing local files using Silverlight.

I created a sample app and pointed it at your mp3 file and it' wouldn't work, however a quick search for sample mp3s, lead me to another freely available (first hit). Using the code/url below, it works ok.

myMediaelement.Source = new Uri("http://www.robtowns.com/music/blind_willie.mp3", UriKind.Absolute);

In regards to the loading, it will start downloading the file when it hits the code that sets the source of the mediaelement. 

So if you set the source for the media element in your constructor or in your loaded event, it will automatically start downloading in the background.

Then you just call myMediaelement.Play(); on the button click event.

Hope this helpful

Adding media to an application is as simple as adding a MediaElement control to the user interface (UI) of the application and providing a Uri to the media you wish to include. All media types supported by Microsoft Windows Media Player 10 are supported in Windows Presentation Foundation (WPF). The following example shows a simple usage of the MediaElement in Extensible Application Markup Language (XAML).

<!-- This page shows a simple usage of MediaElement -->
<Page x:Class="MediaElementExample.SimpleUsage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="SimpleUsage"
    >
  <StackPanel Margin="20">
    <MediaElement Source="media/numbers-aud.wmv" />
  </StackPanel>
</Page>



Follow this link for more help-

 
http://msdn.microsoft.com/en-us/library/aa970915.aspx