Randy has the source code—the original program—for the videoconferencing software. It is reasonably clever in its use of bandwidth. It looks at the stream of frames (individual still images) coming from the pinhole camera and notices that, although the total amount of data in those frames is rather large, the difference from one frame to the next is tiny. It would be altogether different if Frame 1 were a talking head and Frame 2, a fraction of a second later, were a postcard shot of a Hawaiian beach and Frame 3 a diagram of a printed circuit and Frame 4 a closeup of a dragonfly’s head. But in fact, each frame is a talking head—the same person’s head, with minor changes in position and expression. The software can save on precious bandwidth by mathematically subtracting each new frame from the previous one (since, to the computer, each image is just a long number) and then transmitting only the difference.