Windows Phone 8 : Media and Picture Hubs (part 1) - Accessing Music, Playing Music

The phone can store music, pictures, and video. From the user’s perspective, these are stored in the Music and Videos hub and the Pictures hub. You can work with these hubs in several ways. You can access the music in the Music and Videos hub, you can access the pictures in the Pictures hub, and you can register your application to be included in both of these hubs.

using (var library = new MediaLibrary())
{
  // use media library
}

The music library consists of the following types of objects:

• Artist: This is the name of the performer of a song or album.

• Album: This is a collection of songs from one or more artists.

• Genre: This is a named category for songs and albums.

• Song: This is a single piece of music that can belong to a genre, album, and artist.

• Playlist: This is a user-defined list of songs.

The MediaLibrary class exposes these types of objects into collections that can be navigated (as shown in Figure 1). Although these are discrete collections, they each contain all the music in the collection.

FIGURE 1 Music library objects

On the MediaLibrary class, each of these objects is exposed as collections (that support IEnumerable), so simple iteration is straightforward:

using (var library = new MediaLibrary())
{
  // use media library
  foreach (var artist in library.Artists)
  {
    theList.Items.Add(artist.Name);
  }
}

Because these collections support IEnumerable, we can use LINQ against these as well:

using (var library = new MediaLibrary())
{
  var qry = from artist in library.Artists
            where artist.Name == "Shawn Twain"
            select artist;

  var shawn = qry.FirstOrDefault();

  if (shawn != null)
  {
    // Retrieve the songs for that artist.
    var hisSongs = shawn.Songs;
  }
}

As this example shows, after you retrieve the artist you’re looking for you can use the songs for a particular artist, album, or genre. You can also add and delete from the list of songs, but this functionality is implemented as extension methods so you have to add the right namespace to get the APIs for adding and deleting: Microsoft.Xna.Framework.Media.PhoneExtensions.

After you have those extension methods, you can call SaveSong to add a song:

using (var library = new MediaLibrary())
{
  var meta = new SongMetadata()
  {
    Name = "Anne",
    ArtistName = "Shawn Twain",
    AlbumReleaseDate = DateTime.Parse("04/24/2000"),
    AlbumArtistName = "Shawn Twain",
    Duration = TimeSpan.FromSeconds(254),
    TrackNumber = 4
  };

  library.SaveSong(new Uri("/Assets/02-anne.mp3", UriKind.Relative),
    meta,
    SaveSongOperation.CopyToLibrary);
}

Before you can add the song, you must first create a SongMetadata object that contains information about the song, as shown here. After you have that, you can call SaveSong to add the song to the library. The last parameter must specify whether you want to copy or move the song (when your source to the song is in the isolated storage). 

You can also remove a song from the library using the Delete method:

using (var library = new MediaLibrary())
{
  var song = library.Songs.First();

  library.Delete(song);
}

As you can see here, you must have a Song object from the library and then call the Delete method to remove it from the library.

public partial class MainPage : PhoneApplicationPage
{
  DispatcherTimer _xnaTimer = new DispatcherTimer();

  // Constructor
  public MainPage()
  {
    InitializeComponent();

    // Because we're using XNA's MediaPlayer, we need to
    // Use the FrameworkDispatcher to allow events
    _xnaTimer.Interval = TimeSpan.FromMilliseconds(50);
    _xnaTimer.Tick += (s, a) => FrameworkDispatcher.Update();
    _xnaTimer.Start();
  }
  ...
}

After you do that, you can use the MediaPlayer class to play a song:

using (var library = new MediaLibrary())
{
  var qry = from artist in library.Artists
            where artist.Name == "Shawn Twain"
            select artist;

  var shawn = qry.FirstOrDefault();
  if (shawn != null)
  {
    // Retrieve the songs for that artist.
    var hisSongs = shawn.Songs;
    if (MediaPlayer.State != MediaState.Playing)
    {
      MediaPlayer.Play(hisSongs[0]);
    }
  }
}

You need to check the state of the MediaPlayer before you can play new songs, but as long as a song isn’t currently playing, you can just play it by supplying the Song object to the media player. If you have songs you want to play that are not in the media library, you can create your own song objects using the FromUri static method:

var mySong = Song.FromUri("Bridges and Ghosts",
                          new Uri("song.mp3", UriKind.Relative));

if (MediaPlayer.State != MediaState.Playing)
{
  MediaPlayer.Play(mySong);
}

The FromUri method will take a relative URI that picks up songs in your .xap file or an absolute URI to add songs from anywhere on the Internet.

You can also supply a SongCollection to play the entire collection:

// Retrieve the songs for that artist.
var hisSongs = shawn.Songs;
if (MediaPlayer.State != MediaState.Playing)
{
  MediaPlayer.Play(hisSongs);
}

You are limited to playing only the SongCollections that already exist (for example, MediaLibrary.Songs, Artist.Songs, Playlist.Songs, and so on). There is no facility for creating your own list of songs to integrate with the MediaPlayer class.

Playing Songs from Isolated Storage

If you want to play songs directly from isolated storage, you’ll need to use the MediaElement because the MediaPlayer class does not support this capability.