Efficient Interpolation Filters for Chroma Motion Compensation in Video Coding

Interpolation filters for motion compensation play an important role in video coding. Until recently, interpolation filters for luma motion compensation (MC) draw most of the attention while interpolation filters for chroma motion compen-sation are less noticeable. This paper comprehensively analyzes different types of interpolation filters and presents 6-tap DCT based chroma interpolation filters for chroma MC. The proposed interpolation filters are designed considering multiple factors, comprising the characteristics of the chroma component, the frequency response of interpolation filter and the expenses of computational complexity. The experimental results show the proposed method can achieve 0.05%, 1.23% and 1.25% BD-rate reductions on average for Y, Cb and Cr components, respectively, with only 2% decoding time increasing under Random Access configuration, compared with ECM-4.0, which is a reference software developed by JVET, targeting at future video coding technologies beyond VVC. Owing to the good trade-off between coding performance and complexity, the proposed method has been adopted in ECM.