protected function leadMKV()
	{
		$lead = $this->ffprobeFormat("matroska", "webm");

		if ($lead === true)
		{
			if ($this->ffprobeHasVideo() !== false)
			{
				return $this->closeCase("mkv", "video/x-matroska", $this->metadata);
			}
			else
			{
				return false;
			}
		}

		return null;
	}