$re = '/(¶[\S\s]*?¶)/m';
$str = 'This is good text, and should be kept
977
00:36:46,805 --> 00:36:50,874
¶ This is complete junk
And this is also junk, on a second line¶
This is good, and I want to keep it.
¶Garbage on its own line¶
This is good
Good sentence ¶but rubbish inline¶ and this is good
Good
¶ Trash
Rubbish ¶
Good';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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