functions.php

<?php

add_filter( 'x_sliders_meta', 'x_revolution_slider_add_slider_meta_tweek', 1 );
function x_revolution_slider_add_slider_meta_tweek( $meta ) {
	return array_merge( $meta, x_revolution_slider_get_slider_meta_tweek() );
}
if( !function_exists('x_revolution_slider_get_slider_meta_tweek')){
	function x_revolution_slider_get_slider_meta_tweek() {

		$rs      = new RevSlider();
		$sliders = $rs->getArrSliders();
		$data    = array();

		foreach ( $sliders as $s ) {

			$key                  = 'x-slider-rs-' . $s->getID();
			$data[$key]['id']     = $s->getID();
			$data[$key]['slug']   = $s->getAlias();
			$data[$key]['name']   = $s->getTitle();
			$data[$key]['source'] = 'Revolution Slider';

		}

		usort($data, function($a, $b) {
			return $a['name'] <=> $b['name'];
		});
		remove_filter( 'x_sliders_meta', 'x_revolution_slider_add_slider_meta' );
		return $data;

	}

}