video.js無法獲取視頻總時長

        var options = {
            // controls: 'control',
            controls: false,
            preload: 'auto',
            playsinline: true,
            poster: "http://shortmeetadmin.oss-cn-beijing.aliyuncs.com/1515394799463",
        };

        var player = videojs('video', options, function onPlayerReady() {
            videojs.log('Your player is ready!');
            this.play();
          
            console.log(this.duration())    //總是 NaN
        });

https://github.com/videojs/vi...

http://docs.videojs.com/tutor...