pub const FRAME_DURATION_NTSC: Duration;Expand description
Nominal NTSC frame duration: 1 / 60.0988 Hz ≈ 16.6393 ms.
Real hardware alternates 29780-cycle and 29781-cycle frames (the half cycle averages to 60.0988 Hz); for wall-clock pacing we treat the average as a single fixed-point interval and let small slips snap.