code: protected function getDurationFormat(array $config)
      {
          if (isset($config['durationFormat'])) {
              if (!is_string($config['durationFormat'])) {
                  throw new \DomainException(
                      'durationFormat must reference a string',
                      self::ERR_INVALID_DURATIONFORMAT
                  );
              }
              return $config['durationFormat'];
          }
          return '%im%ss';
      }
docs: Extracts a pattern for formatting video durations from configuration.
  
  @param array $config
  @return string
  @throws \DomainException if durationFormat setting is invalid