NETWORK-DRIVEN MOTION ESTIMATION FOR WIRELESS VIDEO TERMINALS

Motion estimation has been shown to help significantly in the compress ion of video sequences, However, since most motion estimation algorith ms require a large amount of computation, it is undesirable to use the m in power constrained applications, such as battery-operated wireless video encoders, This paper describes a nem compression algorithm, ter med network-driven motion estimation (NDME), which reduces the power d issipation of wireless video devices in a networked environment by exp loiting the predictability of object motion, Since the location of an object in the current frame can often be predicted accurately from its location in previous frames, it is possible to optimally partition th e motion estimation computation between the portable devices and high powered compute servers on the wired network, In network-driven motion estimation, a remote high-powered resource at the base-station (or on the wired network), predicts the motion vectors of the current frame from the motion vectors of the previous frames, The base-station sends these predicted motion vectors to a portable video encoder, where mot ion compensation proceeds as usual, Network-driven motion estimation a daptively adjusts the coding algorithm based an the amount of motion i n the sequence, using motion prediction to code portions of the video sequence which contain a large amount of motion and conditional replen ishment: tb code portions of the sequence which contain little scene m otion, This algorithm achieves a reduction in the number of operations performed at the encoder for motion estimation by over two orders of magnitude while introducing minimal degradation to tile decoded video compared with full search encoder-based motion estimation.