K2 item EXTRA FIELDS

$db =& JFactory::getDBO();
$queryz = "SELECT * FROM jos_k2_items WHERE catid = '1' AND trash = '0'";
$db->setQuery( $queryz);
$rows = $db->loadObjectList();


$count_prod=0;

foreach($rows as $row)
{




$extra1 = $row->extra_fields;

$mod=substr($extra1,strpos($extra1,"{\"id\":\"1\",\"value\":\""));
$mod=substr($mod,19,strpos($mod,"}")-20);

echo $mod;
}