Fast motion estimation for HEVC with directional search

The new high-efficiency video coding (HEVC) standard is becoming popular owing to its excellent rate-distortion performance especially for emerging high-resolution applications. In HEVC more flexible coding options and partitioning types are provided for prediction units (PUs) and consequently motion estimation (ME) is more involved than previous video-coding standards. The existing fast ME algorithms, including the test zone search provided in the HEVC reference software, cannot generate high-quality video with reasonable computational complexity. A new fast integer-pixel ME algorithm for HEVC is presented. Starting with the initial motion vector obtained by the advanced motion vector prediction, the proposed directional search extends three search paths from the initial motion vector and considers the highly probable horizontal or vertical movement. Compared to the test zone search, the proposed method saves, on average, 60% time in integer-pixel ME with negligible rate-distortion degradation.