Base-layer motion estimation with limited enhancement-layer search window for hardware H.264/SVC encoder

In the hardware design of ME, memory bandwidth and on-chip memory size are major constraints to be considered, especially for mobile video encoder, so as to reduce power consumption and area. In a spatial scalable video encoder, with limited memory bandwidth and on-chip memory size to fetch and store reference frames, the search window for enhancement layer (EL) becomes relatively smaller than that of base layer (BL). However, the smaller search window in EL causes quality loss because scaled base-layer MVs may not be inside it and therefore inter-layer prediction cannot be fully exploited. To address this issue in the hardware H.264/SVC encoder, the base-layer ME with a new MV cost is proposed in this work. The proposed method can improve the coding efficiency of EL up to around 17 % at the cost of marginal BL quality and trade off the qualities of BL and EL.