$re = '/\[LINETYPE\]([A-Z])\s\[(?:TITLE|STARTTIME)\]([^[\s]*(?: [^[\s]+)*)(?:\s*\[PERFORMER\]([^[ ]*(?: [^[ ]+)*)\s+\[MUSICID\]([^[ ]+)\s+\[LABEL\](\S*(?: \S+)*))?/';
$str = '[LINETYPE]S [STARTTIME]00:00:00
[LINETYPE]M [TITLE]There For You [PERFORMER]Martin Garrix & Troye Sivan [MUSICID]21120 [LABEL]
[LINETYPE]M [TITLE]Shut Up and Dance [PERFORMER]Walk The Moon [MUSICID]20634 [LABEL]
[LINETYPE]M [TITLE]Subeme La Radio [PERFORMER]Enrique Iglesias [MUSICID]21105 [LABEL]
[LINETYPE]C [TITLE]AUTO S2 NON STOP [PERFORMER] [MUSICID]A2-6 [LABEL]
[LINETYPE]M [TITLE]Uptown Funk [PERFORMER]Mark Ronson & Bruno Mars [MUSICID]20533 [LABEL]
[LINETYPE]M [TITLE]Let It Go [PERFORMER]James Bay [MUSICID]20839 [LABEL]
[LINETYPE]S [STARTTIME]01:00:00
[LINETYPE]M [TITLE]There For You [PERFORMER]Martin Garrix & Troye Sivan [MUSICID]21120 [LABEL]
[LINETYPE]M [TITLE]Shut Up and Dance [PERFORMER]Walk The Moon [MUSICID]20634 [LABEL] ';
preg_match_all($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