Generate youtube thumbnail from embed code using php

Generate youtube thumbnail from embed code using php

I have tried to strip the code below
<iframe width="560" height="315" src="//www.youtube.com/embed/QUVdnzC19oU"
frameborder="0" allowfullscreen></iframe>
its working but not stripping the links properly all i get is
http://img.youtube.com/vi/www.youtube.comembedQUVdnzC19oU/0.jpg
instead of
http://img.youtube.com/vi/QUVdnzC19oU/0.jpg
Please find the php code below.
if(preg_match_all('@<iframe\s[^>]*src=[\"|\']([^\"\'\>]+)[^>].*?</iframe>@siu',
$item->introtext, $iframesrc) >0){
if(isset($iframesrc[1])){
$vid = str_replace(
array(
'http://youtu.be/',
'http://www.youtube.com/embed/',
'http://youtube.googleapis.com/v/'), '',
$iframesrc[1][0]);
$vid = preg_replace('@\/.*?@i', '', $vid);
if(!(empty($vid))){
$result = '' .
'<div class="vimage">
<a class="video-link vlink"
href="'.$item->link.'" title="">
<img
src="http://img.youtube.com/vi/'.$vid.'/0.jpg"
/>
<span class="play-icon">&nbsp;</span>
</a>
</div>';
$item->introtext = str_replace($iframesrc['0'], '',
$item->introtext);
}
}
}
Thanks in advance.