stop backstretch slideshow on certain resolutions

Question

Im using JQuery Backstretch (http://srobbin.com/jquery-plugins/backstretch/) to make a nice background gallery. As on mobile i always get some problem with the overlay content i want to stop the backstretch slideshow if the resolution is lower than 767. Then it should only show a simple pic. I've tried with this code:

After loading:

 $.backstretch(["/xp_galerie/8.jpg", "/xp_galerie/7.jpg", "/xp_galerie/9.jpg", ], {duration: 5000, fade: 750});


win_h = $(window).height();
win_w = $(window).width();

if(win_w <=767) {
        $.backstretch('/xp_galerie/9.jpg');
    }

But this shows me the new bg-image, but doesn't stop the slideshow.

thanks for help.

regards thomas