<?php $row = "yyy"; $strcode = "xxx"; echo " onclick=\"changevid('$strcode')\" class='vid' src='https://i...content-available-to-author-only...e.com/vi/$row/mqdefault.jpg'";
Standard input is empty
onclick="changevid('xxx')" class='vid' src='https://i...content-available-to-author-only...e.com/vi/yyy/mqdefault.jpg'