<?php
 
$conteudonoticia = '[caption id="attachment_42478" align="alignleft" width="640"] <img class="wp-image-42478 size-full" src="http://paginalocal/wp-content/uploads/2016/12/20140815_174009.jpg" alt="20140815_174009" width="640" height="480" />Objetivo com a antecipação é garantir comodidade e tranquilidade aos servidores para as festas de final de ano[/caption]';
 
preg_match_all('#\bhttps?://[^,\s()<>]+(?:\([\w\d]+\)|([^,[:punct:]\s]|/))#', $conteudonoticia, $match);
 
 
print_r($match[0]); 

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