Global motion compensation and spectral entropy bit allocation for low complexity video coding

Most standard video compression schemes such as H.264/AVC involve a high complexity encoder with block motion estimation (ME) engine. However, applications such as video reconnaissance and surveillance using unmanned aerial vehicles (UAVs) require a low complexity video encoder. Additionally, in such applications, the motion in the video is primarily global and due to the known movement of the camera platform. Therefore in this work, we propose and investigate a low complexity encoder with global motion based frame prediction and no block ME. We show that for videos with mostly global motion, this encoder performs better than a baseline H.264 encoder with ME block size restricted to 8×8. Furthermore, the quality degradation of this encoder with decreasing bit rate is more gradual than that of the baseline H.264 encoder since it does not need to allocate bits across motion vectors (MVs) and residue data. We also incorporate a spectral entropy based coefficient selection and quantizer design scheme that entails latency and demonstrate that it helps achieve more consistent frame quality across the video sequence.