pub fn expand_text(fmt: &str, t: f64, lt: f64, fps: f64) -> StringExpand description
Expand a text node’s format at time t (timeline seconds, lt clip-local): {frame} is the
timeline frame number, {time} the timeline clock, {n} the frames since the clip started — so a
counter is {n} and a clock is {time}. Anything else is left alone.