Windows phone 8 on emulator - why can't I play audio files? - mp3

Question

I'm converting an app that was written in Silverlight, and so far I've succeeded in solving all of the problems, except for one:
For some reason, the emulator refuses to play any audio files of the app, and it doesn't even throw an exception. I've checked, and in the ringtone category it can make sounds.
The original code was :
<Grid x:Name="sharedFullScreenFilePathContainer"
Tag="{Binding StringFormat=\{0\},Converter={StaticResource fullScreenImageConverter}}">
<Image x:Name="fullScreenImage" Stretch="Fill"
Source="{Binding ElementName=sharedFullScreenFilePathContainer,Path=Tag, StringFormat=../Assets/images/\{0\}.jpg}"
ImageFailed="onFullScreenImageFailedToLoad" MouseLeftButtonDown="onPressedOnFullScreenImage" />
<MediaElement x:Name="mediaPlayer" AutoPlay="True"
Source="{Binding ElementName=sharedFullScreenFilePathContainer,Path=Tag, StringFormat=../Assets/sounds/\{0\}.wma}" />
</Grid>
so, the image that I set to this item's context is really shown, but the sound that really exists on the path I set to it doesn't play (I've checked in the "Bin" folder).
I've tried to use code instead of xaml, but I still have the same problem.
I've tried this (though it's usually used for background music):
AudioTrack audioTrack = new AudioTrack(new Uri("../Assets/sounds/" + fileToOpen, UriKind.Relative), "", "", "", null);
BackgroundAudioPlayer player = BackgroundAudioPlayer.Instance;
player.Track = audioTrack;
player.Play();
It didn't play anything, and also didn't throw any exception.
I've also tried the next code, but it throws an exception (file not found exception) probably because I don't call it right:
Stream stream = TitleContainer.OpenStream("#Assets/sounds/" + fileToOpen);
SoundEffect effect = SoundEffect.FromStream(stream);
FrameworkDispatcher.Update();
effect.Play();
I've also tried using wma files but it also didn't work.
I also tried to play with the "copy to output directory" parameter of the mp3 files (to "always" and "only if new" ) and with the "build action" parameter (to "none" and "content" ). Nothing helps.
Can anyone please help me? I didn't develop for Silverlight/WP for a very long time and I can't find out how to fix it .
Btw, since later I need to know when the sound has finished playing (and also to be able to stop it), I would like to use code anyway. I would be happy if you could also tell me how to do it too (I can ask it on a new post if needed).
EDIT:
ok , i've found out the problem : i kept getting a weird exception when using the MediaPlayer.Play() method , and after checking out about the exception , i've found out that it's a known issue , and that i need to call FrameworkDispatcher.Update(); right before i call the Play() method .
so the solution would be to do something like this:
Song song = Song.FromUri(...);
MediaPlayer.Stop();
FrameworkDispatcher.Update();
MediaPlayer.Play(song);
the exception is:
'System.InvalidOperationException' occurred in System.Windows.ni.dll"
i've found the solution here .
Now the question is why , and how come I didn't find anything related to it in the demos of windows phone ? Also , i would like to know what this function does .
ok , since nobody gave me an answer to both questions , and I still wish to give the bounty , I will ask another question :
If there is really no solution other than using the MediaPlayer class for windows phone , how do i capture the event of finishing playing an audio file ? Even getting the audio file duration doesn't work (keeps returning 0 length , no matter which class i've tried to use) ...

Answer 1

The BackgroundAudioPlayer can play files only from isolated storage or from a remote URI, that is why you can here anything!
If you have your file as resources in your app, you must first copy them to the isolated store, and then make a reference to the file in the isolated store to your BackgroundAudioPlayer.
private void CopyToIsolatedStorage()
{
using (IsolatedStorageFile storage = IsolatedStorageFile.GetUserStoreForApplication())
{
string[] files = new string[]
{ "Kalimba.mp3",
"Maid with the Flaxen Hair.mp3",
"Sleep Away.mp3" };
foreach (var _fileName in files)
{
if (!storage.FileExists(_fileName))
{
string _filePath = "Audio/" + _fileName;
StreamResourceInfo resource = Application.GetResourceStream(new Uri(_filePath, UriKind.Relative));
using (IsolatedStorageFileStream file = storage.CreateFile(_fileName))
{
int chunkSize = 4096;
byte[] bytes = new byte[chunkSize];
int byteCount;
while ((byteCount = resource.Stream.Read(bytes, 0, chunkSize)) > 0)
{
file.Write(bytes, 0, byteCount);
}
}
}
}
}
}
And then you can make a list of your songs
private static List<AudioTrack> _playList = new List<AudioTrack>
{
new AudioTrack(new Uri("Kalimba.mp3", UriKind.Relative),
"Kalimba",
"Mr. Scruff",
"Ninja Tuna",
null),
new AudioTrack(new Uri("Maid with the Flaxen Hair.mp3", UriKind.Relative),
"Maid with the Flaxen Hair",
"Richard Stoltzman",
"Fine Music, Vol. 1",
null),
new AudioTrack(new Uri("Sleep Away.mp3", UriKind.Relative),
"Sleep Away",
"Bob Acri",
"Bob Acri",
null),
// A remote URI
new AudioTrack(new Uri("http://traffic.libsyn.com/wpradio/WPRadio_29.mp3", UriKind.Absolute),
"Episode 29",
"Windows Phone Radio",
"Windows Phone Radio Podcast",
null)
};
And play your tracks!
private void PlayNextTrack(BackgroundAudioPlayer player)
{
if (++currentTrackNumber >= _playList.Count)
{
currentTrackNumber = 0;
}
PlayTrack(player);
}
private void PlayPreviousTrack(BackgroundAudioPlayer player)
{
if (--currentTrackNumber < 0)
{
currentTrackNumber = _playList.Count - 1;
}
PlayTrack(player);
}
private void PlayTrack(BackgroundAudioPlayer player)
{
// Sets the track to play. When the TrackReady state is received,
// playback begins from the OnPlayStateChanged handler.
player.Track = _playList[currentTrackNumber];
}

Answer 2

If you want the MediaElement to work from your code you can do something like this!
MediaElement me = new MediaElement();
// Must add the MediaElement to some UI container on
// your page or some UI-control, otherwise it will not play!
this.LayoutRoot.Children.Add(me);
me.Source = new Uri("Assets/AwesomeMusic.mp3", UriKind.RelativeOrAbsolute);
me.Play();

Answer 3

Use the MediaElement instead, this can play media files stored in your application, but stops playing when the application stops (you can make some advance chance to your app so it keep running, but it will not work very well)
In your XAML:
<Button x:Name="PlayFile"
Click="PlayFile_Click_1"
Content="Play mp3" />
In your Code behind:
MediaElement MyMedia = new MediaElement();
// Constructor
public MainPage()
{
InitializeComponent();
this.LayoutRoot.Children.Add(MyMedia);
MyMedia.CurrentStateChanged += MyMedia_CurrentStateChanged;
MyMedia.MediaEnded += MyMedia_MediaEnded;
}
void MyMedia_MediaEnded(object sender, RoutedEventArgs e)
{
System.Diagnostics.Debug.WriteLine("Ended event " + MyMedia.CurrentState.ToString());
// Set the source to null, force a Close event in current state
MyMedia.Source = null;
}
void MyMedia_CurrentStateChanged(object sender, RoutedEventArgs e)
{
switch (MyMedia.CurrentState)
{
case System.Windows.Media.MediaElementState.AcquiringLicense:
break;
case System.Windows.Media.MediaElementState.Buffering:
break;
case System.Windows.Media.MediaElementState.Closed:
break;
case System.Windows.Media.MediaElementState.Individualizing:
break;
case System.Windows.Media.MediaElementState.Opening:
break;
case System.Windows.Media.MediaElementState.Paused:
break;
case System.Windows.Media.MediaElementState.Playing:
break;
case System.Windows.Media.MediaElementState.Stopped:
break;
default:
break;
}
System.Diagnostics.Debug.WriteLine("CurrentState event " + MyMedia.CurrentState.ToString());
}
private void PlayFile_Click_1(object sender, RoutedEventArgs e)
{
// Play Awesome music file, stored as content in the Assets folder in your app
MyMedia.Source = new Uri("Assets/AwesomeMusic.mp3", UriKind.RelativeOrAbsolute);
MyMedia.Play();
}

Answer 4

Audio track plays audio files stored in isolated storage or streamed over the internet.

Answer 5

Playing audio files stored within the application package works fine for me. I got files named like "Alarm01.wma" in project folder Resources\Alarms. I then play these sounds like this:
using Microsoft.Xna.Framework.Media;
...
Song s = Song.FromUri("alarm", new Uri(#"Resources/Alarms/Alarm01.wma", UriKind.Relative));
MediaPlayer.Play(s);
Also don't forget to reference Microsoft.Xna.Framework library.
I guess it should work fine for mp3 files and files stored in IsolatedStorage as well.