1. A device comprising: a camera to receive multiple frames of a face of a user, the multiple frames comprising a sequence of more than two frames of the face of the user, the camera operating at a receiving frame rate higher than a display frame rate of a display device of a second device displaying the multiple facial frames such that received adjacent frames by the camera comprise content from a same displayed frame of the display device; and a processor coupled to the camera, the processor configured to: perform a function based upon components of the face of the user relative to one another to determine measured facial features for two adjacent frames of the multiple frames by determining, for each set of two adjacent frames of the multiple frames, first measured facial features for a first adjacent frame of the set of two adjacent frames and second measured facial features of a second adjacent frame of the set of two adjacent frames; and determine, for each set of two adjacent frames, whether the measured facial features for the first and second adjacent frames indicate that the first and second adjacent frames are sufficiently different to indicate a liveness of the user by comparing the first measured facial features and the second measured facial features.