On the Minimum Perceptual Temporal Video Sampling Rate and its Application to Adaptive Frame Skipping

Media technology, in particular video recording and playback, keeps improving to provide users with high-quality real and virtual visual content. In recent years, increasing the temporal sampling rate of videos and the refresh rate of displays has become one focus of technical innovation. This raises the question, how high the sampling and refresh rates should be? To answer this question, we determine the minimum temporal sampling rate at which a video should be presented to make temporal sampling imperceptible to viewers. Through a psychophysical study, we find that this minimum sampling rate depends on both the speed of the objects in the image plane and the exposure time of the recording camera. We propose a model to compute the required minimum sampling rate based on these two parameters. In addition, state-of-the-art video codecs employ motion vectors from which the local object movement speed can be inferred. Therefore, we present a procedure to compute the minimum sampling rate given an encoded video and camera exposure time. Since the object motion speed in a video may vary, the corresponding minimum frame rate is also varying. This is why the results of this paper are particularly applicable when used together with adaptive frame rate computer generated graphics or novel video communication solutions that drop insignificant frames. In our experiments, we show that videos played back at the minimum adaptive frame rate achieve an average bit rate reduction of 26% compared to constant frame rate playback, while perceptually no difference can be observed.