A method includes receiving head-tracking data that describes one or more positions of one or more people while the one or more people are viewing a three-dimensional video. The method further includes generating video segments from the three-dimensional video. The method further includes, for each of the video segments: determining a directional encoding format that projects latitudes and longitudes of locations of a surface of a sphere onto locations on a plane, determining a cost function that identifies a region of interest on the plane based on the head-tracking data, and generating optimal segment parameters that minimize a sum-over position for the region of interest.