Perch template filter for getting a Perch item's reading length in minutes

PerchTemplateFilter_Length

<?php

class PerchTemplateFilter_length extends PerchTemplateFilter 
{
    public function filterBeforeProcessing($value, $valueIsMarkup = false)
    {
      $word = str_word_count(strip_tags($value));
      $m = floor($word / 200);
      $s = floor($word % 200 / (200 / 60));

      if ($m > 0) {
        $est = $m . ' minute' . ($m == 1 ? '' : 's');
      } else {
        $est = 1 . ' minute';
      }

      return $est;
    }
}

PerchSystem::register_template_filter('length', 'PerchTemplateFilter_length');

I'm not sure if this is possible, it's mainly for text fieldtypes. If I have some time I'll take a peek!