Help with code

[dkharp]

I am using this code for aeva: How do I change it to random?? Please help:

$start = 0;
$max_number_of_pics = 4;
$sort = 'm.time_added DESC';

echo '<div style="width: 100%; overflow: hidden;">';

global $sourcedir;
require_once($sourcedir . '/Aeva-Subs.php');   
echo aeva_listItems(aeva_getMediaItems($start, $max_number_of_pics,$sort, 'm.id_media'), true, '', 4);

echo'</div>';