Complexity-Aware TZS Algorithm for Mobile Video Encoders
Keywords:Embedded Devices, HEVC, Complexity Reduction, Motion Estimation, Test Zone Search
Video applications are significantly growing in the last years, especially in embedded/mobile systems. Modern video compression algorithms and standards, such as the High Efficiency Video Coding (HEVC), achieved a high efficiency in compression ratio. However, such efficiency has caused an augment on the complexity to encode videos. This is a serious problem especially in mobile systems, which present restrictions on processing and energy consumption. This paper presents an enhanced Test Zone Search (TZS) algorithm, aiming at complexity reduction of the Motion Estimation (ME) process in the HEVC standard and focusing efficient hardware design for mobile encoders. The proposed algorithm is composed of two strategies: an early termination scheme for TZS, called e-TZS, and the Octagonal-Axis Raster Search Pattern (OARP). When combined and implemented in the HEVC reference encoder, the strategies allowed an average complexity reduction of 75.16% in TZS, with a negligible BD-rate increase of only 0.1242% in comparison to the original algorithm. Besides, the approach presents an average block matching operation reduction of 80%, allowing hardware simplification and decreasing memory access.