Hardware Deceleration of Kvazaar HEVC Encoder

High Efficiency Video Coding (HEVC) doubles the coding efficiency of the prior Advanced Video Coding (AVC) standard but tackling its huge com- plexity calls for efficient HEVC codec implementations. The recent advances in Graphics Processing Units (GPUs) have made programmable general-purpose GPUs (GPGPUs) a popular option for accelerating various video coding tools. Massively parallel GPU architectures are particularly well suited for hardware- oriented full search (FS) algorithm in HEVC integer motion estimation (IME). This paper analyzes the feasibility of a GPU-accelerated FS implementation in the practical Kvazaar open-source HEVC encoder. According to our evaluations, implementing FS on AMD Radeon RX 480 GPU makes Kvazaar 12.5 times as fast as the respective anchor implemented entirely on an Intel 8-core i7 processor. However, the obtained speed gain is lost when fast IME algorithms are put into use in the anchor. For example, executing the anchor with hexagon-based search (HEXBS) algorithm is almost two times as fast as our GPU-accelerated proposal and the benefit of GPU offloading is reduced to a slight coding gain of 1.2%. Our results show that accelerating IME on a GPU speeds up non-practical encoders due to their enormous inherent complexity but the price paid with practical en- coders tends to be too high. Conditional processing schemes of fast IME algo- rithms can be efficiently executed on processors without any substantial coding loss over that of FS. Nevertheless, we still believe there might be room for ex- ploiting GPU on IME acceleration but GPU-parallelized fast algorithms are needed to get value for additional implementation cost and power budget.acceptedVersionPeer reviewe