Parallel Integer Motion Estimation for High Efficiency Video Coding (HEVC) Using OpenCL

High Efficiency Video Coding is able to reduce the bit-rate up to 50% compared to H.264/AVC, using increasingly complex computational processes for motion estimation. In this paper, some motion estimation operations are parallelised using Open Computing Language in a Graphics Processing Unit. The parallelisation strategy is three-fold: calculation of distortion measurement using \(4 \times 4\) blocks, accumulation of distortion measure values for different block sizes and calculation of local minima. Moreover, we use 3D-arrays to store the distortion measure values and the motion vectors. Two 3D-arrays are used for transferring data from GPU to CPU to continue the encoding process. The proposed parallelisation is able to reduce the execution time, on average 52.5%, compared to the HEVC Test Model. Additionally, there is a negligible impact on the compression efficiency, as an increment in the BD-BR, on average 2.044%, and a reduction in the BD-PSNR, on average 0.062%.