+// _demoseeking_speed_factor
+// Factor of remaining time to seek speed. Default 10.
+// The seek speed is defined by the formula
+//
+// 1.0 + [remaining seek seconds] * _demoseeking_speed_factor
+//
+// bound by _demoseeking_min_speed and _demoseeking_max_speed.
+// _demoseeking_fast_speed
+// Seek speed above which rendering is disabled. Default 80.