.htaccess

RewriteEngine On
RewriteBase /swav
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php [L]

index.php

<?php
preg_match('/\/swav\/[\D.]+(\d*).+/', $_SERVER['REQUEST_URI'], $matches);

$pic = $matches[1] % 207;

$pics = array();
foreach (glob("/var/www/calref-new/chat/emoticon-packs/ponicons/*.png") as $filename) {
  // the above path should point to the proper directory in calref/cadence
  $pics[] = $filename;
}
header("Content-Type: image/png");

// 5482 sy
// 2001 aran

if ($matches[1] == 5482) {
  echo file_get_contents("/var/www/calref-new/chat/emoticon-packs/ponicons/sybeam.png");
} elseif ($matches[1] == 2001) {
  echo file_get_contents("/var/www/calref-new/chat/emoticon-packs/ponicons/aran.png");
} else {
  echo file_get_contents($pics[$pic]);
}