如何在spotify api上播放完整的歌曲

我只播放预览(0:30)，但我想播放完整的歌曲(3:10)。我已经尝试了一些方法，但没有成功。它也在播放预览我怎么玩满了歌呢?

mediaplayer是MediaElement.

    mediaplayer.Source = new Uri("https://api.spotify.com/v1/tracks/4pn0G7yHNfTgRYRWca8gYA",UriKind.RelativeOrAbsolute);
or 
mediaplayer.Source = new Uri(Stream_url.preview_url.ToString(), UriKind.RelativeOrAbsolute);
"href" : "https://api.spotify.com/v1/tracks/4pn0G7yHNfTgRYRWca8gYA",
{
    "href" : "https://api.spotify.com/v1/albums/60mvULtYiNSRmpVvoa3RE4/tracks?offset=0&limit=50",
    "items" : [ {
        "artists" : [ {
            "external_urls" : {
              "spotify" : "https://open.spotify.com/artist/0TnOYISbd1XYRBk9myaseg"
            },
            "href" : "https://api.spotify.com/v1/artists/0TnOYISbd1XYRBk9myaseg",
            "id" : "0TnOYISbd1XYRBk9myaseg",
            "name" : "Pitbull",
            "type" : "artist",
            "uri" : "spotify:artist:0TnOYISbd1XYRBk9myaseg"
        }, {
            "external_urls" : {
                "spotify" : "https://open.spotify.com/artist/2DlGxzQSjYe5N6G9nkYghR"
            },
            "href" : "https://api.spotify.com/v1/artists/2DlGxzQSjYe5N6G9nkYghR",
            "id" : "2DlGxzQSjYe5N6G9nkYghR",
            "name" : "Jennifer Lopez",
            "type" : "artist",
            "uri" : "spotify:artist:2DlGxzQSjYe5N6G9nkYghR"
        }, {
            "external_urls" : {
                "spotify" : "https://open.spotify.com/artist/2OjoIDVPQKT9B7loZbPEfp"
            },
            "href" : "https://api.spotify.com/v1/artists/2OjoIDVPQKT9B7loZbPEfp",
            "id" : "2OjoIDVPQKT9B7loZbPEfp",
            "name" : "Claudia Leitte",
            "type" : "artist",
            "uri" : "spotify:artist:2OjoIDVPQKT9B7loZbPEfp"
        } ],
        "available_markets" : [ "AD", "AR", "AT", "AU", "BG", "BO", "BR", "CA", "CH", "CL", "CO", "CR", "CY", "CZ", "DE", "DK", "DO", "EC", "ES", "FR", "GR", "GT", "HK", "HN", "HU", "IE", "IS", "IT", "LI", "MC", "MT", "MX", "MY", "NI", "NO", "NZ", "PA", "PE", "PH", "PL", "PT", "PY", "RO", "SG", "SI", "SK", "SV", "TR", "TW", "UY" ],
        "disc_number" : 1,
        "duration_ms" : 222466,
        "explicit" : false,
        "external_urls" : {
            "spotify" : "https://open.spotify.com/track/4pn0G7yHNfTgRYRWca8gYA"
        },
        "href" : "https://api.spotify.com/v1/tracks/4pn0G7yHNfTgRYRWca8gYA",
        "id" : "4pn0G7yHNfTgRYRWca8gYA",
        "name" : "We Are One (Ole Ola) [The Official 2014 FIFA World Cup Song]",
        "preview_url" : "https://p.scdn.co/mp3-preview/4e6c03963fa6a6720648540282afc75f4df744c9",
        "track_number" : 1,
        "type" : "track",
        "uri" : "spotify:track:4pn0G7yHNfTgRYRWca8gYA"
    } ],
    "limit" : 50,
    "next" : null,
    "offset" : 0,
    "previous" : null,
    "total" : 1

}