$re = '/(\d+)[\n\r]([\d:,]+\s-->\s[\d:,]+)[\n](.+(?:[\n]*[^\d|^\n]+)*)/m';
$str = '0
00:00:00,000 --> 00:00:00,000
Hello world!
1
00:00:00,000 --> 00:00:00,000
Hello world!
This is my new world.
2
00:00:00,000 --> 00:00:00,000
Hello guys!
Hello guys!
Hello guys!
Hello guys!';
preg_match_all($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