GPU-based optimization for sample adaptive offset in HEVC

The latest high efficiency video coding (HEVC) standard achieves about 50% bit-rate reduction at equivalent visual quality compared to H.264/AVC. Sample adaptive offset (SAO) is one of the newly adopted tools right after deblocking filter, which can improve both coding efficiency and visual quality. However, for real-time encoding scenarios, the complexity of SAO is usually too high to be enabled. In this paper, a GPU-based optimization algorithm is proposed to reduce the complexity of SAO. Experiments are conducted based on the state-of-the-art open source HEVC encoder, i.e. X265. Results show that the proposed algorithm can reduce about 70% processing time of SAO on average without sacrifice of coding efficiency.