$re = '/^\d\d:\d\d:\d\d.\d\d\d ;; \d\d:\d\d:\d\d.\d\d\d .*((?:\n(?!\d\d:\d\d:\d\d.\d\d\d ;; \d\d:\d\d:\d\d.\d\d\d).*)*)/m';
$str = '00:00:09.476 ;; 00:00:11.111 side:start top:15% bottom:10% sound:80%
FOO BAR FOO FOO FOO BAR
00:00:11.111 ;; 00:00:12.278 side:start top:15% bottom:10% sound:78%
BAR BAR BAR\' BAR. FOO.BAR
test
00:00:12.278 ;; 00:00:14.447 side:start top:15% bottom:10% sound:43%
BOO.BOO. FARFAR.FAR';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php