How fast is too fast? evaluating fast forward surrogates for digital video

To support effective browsing, interfaces to digital video libraries should include video surrogates (i.e., smaller objects that can stand in for the videos in the collection, analogous to abstracts standing in for documents). The current study investigated four variations (i.e., speeds) of one form of video surrogate: a fast forward created by selecting every Nth frame from the full video. In addition, it tested the validity of six measures of user performance when interacting with video surrogates. Forty-five study participants interacted with all four versions of the fast forward surrogate, and completed all six performance tasks with each. Surrogate speed affected performance on four of the measures: object recognition (graphical), action recognition, linguistic gist comprehension (full text), and visual gist comprehension. Based on these results, we recommend a fast forward default speed of 1:64 of the original video keyframes. In addition, users should control the choice of fast forward speed to adjust for content characteristics and personal preferences.