js hook

   function xs_hook_js() {
        $slideshow = '';
        $slides = xs_get_option('theme_options', 'main_slider');

        if (is_array($slides)) {
            foreach ($slides as $arr) {
                $slideshow .= "'" . $arr['img_src'] . "',";
            }
        }
        trim($slideshow, ",");
        $output = "
/* ================================  BACKGROUND SLIDESHOW  =================================== */
jQuery(document).ready(function($) {
$.backstretch([

  // you can additional images in here with comma separated values
" . $slideshow . "

  ], {
  fade: " . xs_get_option('theme_options', 'fading_speed') . ",
  duration: " . xs_get_option('theme_options', 'animation_pause') . "
});

});";

        echo "<script>$output</script>";
    }

    add_action('wp_footer', 'xs_hook_js', 99);
}