Extends ParsedownExtra. Links to images become images, YouTube links become embedded players, and tables get Bootstrap 4 classes.
Composer
> composer require ryangarber/tripdown
Pure PHP
<?php
require('path/to/Parsedown.php');
require('path/to/ParsedownExtra.php');
require('src/Tripdown.php');
Simply replace
$parsedown = new Parsedown();
with
$parsedown = new Tripdown();