Fast PU Early Termination Algorithm Based on WMSE for ERP Video Intra Prediction

As virtual reality becomes more popular, 360-degree video coding becomes challenging. Projected videos of 360-degree videos and traditional videos are both planar videos, but the projected videos have distortion whose degree depends on the latitude. Traditional coding algorithms cannot effectively adapt to this feature, and 360-degree videos typically have high resolution and frame rate, which results in a high coding complexity. In this study, a fast prediction unit (PU) early termination algorithm based on weighted mean square error (WMSE) of 360-degree video is proposed. In the proposed algorithm, WMSE is used as a basis for the early termination of further PU partitioning. First, the full intra prediction process of the current CU is performed. After that, the similarity between the current CU and its four sub-CUs is calculated using WMSE for 2N×2N; and distortion between predicted and original blocks is calculated using WMSE for N×N. the similarity and distortion is used to terminate PU partitioning. The experimental results show that the algorithm achieves a 31% time reduction, and an average of only 0.3% of the luma Bjontegaard delta rate (BD rate) increases.