Low-complexity video encoding for UAV reconnaissance and surveillance

Most video compression schemes like H.264/AVC have a high-complexity encoder with a block motion estimation (ME) engine and a low-complexity decoder. However, applications such as unmanned aerial vehicle (UAV) reconnaissance and surveillance require low-complexity video encoders. Furthermore, in such applications, the majority of the motion in the video sequences is due to the movement of the UAV and the camera mounts which is known. Motivated by this, we propose and investigate a low-complexity encoder with global motion compensation and spectral entropy based bit allocation, but without block ME. The spectral entropy based bit allocation exploits latency to look ahead at data before choosing and coding the coefficients most important for retaining signal fidelity. We show that the proposed encoder achieves better quality at lower bit rates with lower quality variation than that of the H.264 encoder with ME block size restricted to 8×8 for videos typical of UAV flyovers. Compared to the H.264 encoder with 8×8 ME blocks, the proposed encoder requires fewer computations and memory accesses.