How to merge audio and video in JW Player?

We have some .mp4 videos which has no audio. Now i want to add a audio track to that videos. I have implemented all player functionality in JW Player. Is it possible to play both the .mp4 and .mp3 files at the same time? if yes please guide me how to do.

My current code is like below.

<script type='text/javascript'>
jwplayer('player').setup({
        width: '60%',
        height: '60%',
        primary: "flash",
        playlist: [{
            image: "15.png",
            sources: [{ 
              file: "anim_card_flip.mp4"
            }],
            title: "RK Movie Trailer",
            tracks: [{  // i want to specify audio file like this
              file: "ringtone.mp3"
            }]
        }]   
});