怎的将QVOD与bdhd视频分开

怎样将QVOD与bdhd视频分开
$str= array("qvod://188284189|D14FE97964E040D3749117C6DD4AF7C1|隔世天师_1.rmvb",
  "bdhd://189472486|8863B0E43C1793FF954B11D8EE1420B6|隔世天师_2.rmvb",
"bdhd://182846652|D2E7A0B60BB6703465AC320092595B2F|隔世天师_3.rmvb",
"qvod://196033332|785E9B35B5460BE82758E08E642216BD|隔世天师_4.rmvb",
"bdhd://204033343|B0E324E1DBCD97C62783E328053F31FE|隔世天师_5.rmvb",
"bdhd://190741751|6C72996A18EC2A9C3B49ADF675E4CF0D|隔世天师_6.rmvb",
"bdhd://188025374|D417B47A1F98E0073819F8F1EEF8F14B|隔世天师_7.rmvb");


怎样将QVOD与bdhd分开显示.

foreach($str as $v) {<br />
  $res[substr($v, 0, 4)]][] = $v;<br />
}<br />
print_r($res);