无法获取我的MP3文件的完整持续时间

我试图获得完整的MP3文件，但它返回了NaN，

这是我的代码：

 <script>
            $f("player", "http://releases.flowplayer.org/swf/flowplayer-3.2.7.swf", {
                clip: {
                    // our song
                    url: '1.mp3',

                    // when music starts grab song's metadata and display it using content plugin
                    onStart: function(){
                        var fullduration = parseInt(this.getClip().fullDuration, 10);
                        alert(fullduration);
                        var p = this, c = p.getClip(), d;
                        timer = setInterval(function(){
                            d = showtime(c.fullDuration);
                            $("a[href=" + c.url + "] > samp").html(showtime(p.getTime()) + "/" + d);
                        }, 1000);
                    }
                },
                plugins: {
                    // content plugin settings
                    content: {
                        url: 'flowplayer.content-3.2.0.swf',
                        backgroundColor: '#002200',
                        top: 25,
                        right: 25,
                        width: 160,
                        height: 60
                    },
                    // and a bit of controlbar skinning  
                    controls: {
                        backgroundColor: '#002200',
                        height: 30,
                        fullscreen: false,
                        autoHide: false,
                        volume: false,
                        mute: true,
                        time: true,
                        stop: false,
                        play: false
                    }
                }
            });
        </script>