A typical value ofτwe studied is16—this refreshing speed is roughly 2 frames sampled persecond for 30-fps videos.

his method has been a foundation of manycompetitive results in the literature [12,13,55].

One path-way is designed to capture semantic information that can begiven by images or a few sparse frames, and it operates atlowframe rates andslowrefreshing speed. In contrast, theother pathway is responsible for capturing rapidly changingmotion, by operating atfastrefreshing speed and high tem-poral resolution. Despite its high temporal rate, this pathwayis made verylightweight,e.g.,∼20% of total computation.This is because this pathway is designed to have fewer chan-nels and weaker ability to process spatial information, whilesuch information can be provided by the first pathway in aless redundant manner.

a Slow pathway, operating at low framerate, to capture spatial semantics, and (ii) a Fast path-way, operating at high frame rate, to capture motion atfine temporal resolution.