1. A system comprising:an interface configured to receive a new video frame of a video stream;
control logic coupled to the interface, wherein the control logic is configured to generate estimates of block-level pixel activity for the new video frame based on:
motion estimation data for the new video frame; and
previously calculated block-level pixel activity from a reference video frame;
an encoder configured to generate an encoded video frame based on the estimates, wherein the encoded video frame represents the new video frame.