+ /* note to jack1 developers: ardour also always starts the engine
+ * in async mode (no jack2 --sync option) which adds an extra cycle
+ * of latency with jack2 (and *3 would be correct)
+ * The value can also be wrong if jackd is started externally..
+ *
+ * At the time of writing the ALSA backend always uses double-buffering *2,
+ * The Dummy backend *1, and who knows what ASIO really does :)
+ *
+ * So just display the period size, that's also what
+ * ARDOUR_UI::update_sample_rate() does for the status bar.
+ * (the statusbar calls AudioEngine::instance()->usecs_per_cycle()
+ * but still, that's the buffer period, not [round-trip] latency)
+ */