PHP to get random title for videos

Good day. This is a section of my code that goes and gets videos from any video site. What I'm having issues with is having it post a random title, that are all in a text file called titles.txt. What I'm wanting to accomplish is have my script go pull the video embed code, the duration, the tags, etc. Which all works fine until I get to the title part where it pulls locally from the server from the text file. I get a 500 error in the browser when I try to run the script. Here is the code I have that is responsible for putting the title in.

                    $video  = array(
                        'user_id'     => $this->user_id,
                        'status'      => $this->status,                     
                        'site'        => 'xvideos',
                        'id'          => '',
                        'embeddable'  => true,                      
                        'url'         => '',
                        'titles'       => '',
                        'title'       => '',
                        'description' => '',
                        'tags'        => '',
                        'category'    => '',
                        'thumbs'      => array(),
                        'duration'    => 0,
                        'embed'       => '' 

                    function random_title () 
                    { 
                    $titles = file ("titles.txt", FILE_IGNORE_NEW_LINES);
                    $num = rand (0, intval (count ($titles) / 3)) * 3;
                    return ucwords($titles[$num]);
                    }

                    //Title
                    if(preg_match('/title="(.*?)"/', $match, $matches_title)) {
                        $video['title'] = random_title(). ' - My site name';
                    } else {
                        $this->errors[] = 'Failed to get video title for '.$video['url'].'!';
                        if (!$this->debug) continue;
                        else $debug_e[] = 'TITLE';

Can someone help me out with this please so that it will function correctly. I'm kinda lost at the moment on how to get this code to run correctly. Thank you.