A low complexity and high performance interpolation filter for MPEG IVC
Fractional-pel motion compensation is widely adopted in the modern video coding standards such as H.264/AVC, AVS, and HEVC etc. The interpolation filter is a critical factor that influences the coding efficiency. In this paper, a generation algorithm of interpolation filter coefficients is utilized. Based on the coefficients generation algorithm, three different tap filters, namely 6 tap, 8 tap, 10tap, are tested. A combination of 6 tap and 8 tap interpolation filters is proposed and proved to be optimal scheme considering both performance and computational complexity. And it is beneficial to make software optimization more effective, especially when SIMD-like (Single Instruction Multiple Data) operation is used. Experiments show that the average BD-rate gains on luma Y, chroma U and V are 8.01%, 5.08% and 4.98% for CS1 (Constraint set 1), and 9.21%, 7.53% and 7.63% for CS2 (Constraint set 2) in MPEG IVC reference software ITM5.0, compared with the traditional IVC interpolation method. The coding efficiency gains are significant for some video sequences and can reach up to 28.7%. With the merits of high performance and low complexity, our proposed method is formally adopted by MPEG IVC.