Cost-Based Search Ordering for Rate-Constrained Motion Estimation Applied to HEVC

In the context of motion estimation for video coding, combining a successive elimination algorithm (SEA) with a motion estimation algorithm reduces the number of computed cost functions without impact on rate or distortion. The SEAs use the sum of absolute differences to eliminate motion vector candidates in the search area that cannot improve the current minimum. The novelty in this paper is that instead of relying on a static geometric pattern (i.e., like a spiral), we proposed a dynamic algorithm that creates a cost-based search orderings. A dynamic cost-based search ordering not only improves elimination but also allows for early termination which removes, on average, 61% of the block-matching loop iterations performed by the rate-constrained successive elimination algorithm (RCSEA). Our experiments show that the proposed solution is 5 times faster than the high efficiency video coding (HEVC) HM encoder software in full search mode with a 0.02% impact on BD-Rate. This is twice the speed of the HEVC HM software encoder using only the RCSEA.