Multicomponent Secondary Transform

The Alliance for Open Media has recently initiated coding tool exploration activities towards the next-generation video coding beyond AV1. In this regard, a frequency-domain coding tool, which is designed to leverage the cross-component correlation existing between collocated chroma blocks, is explored in this paper. The tool, henceforth known as multi-component secondary transform (MCST), is implemented as a low complexity secondary transform with primary transform coefficients of multiple color components as input. The proposed tool is implemented and tested on top of libaom. Experimental results show that, compared to libaom, the proposed method achieves an average 0.34% to 0.44% overall coding efficiency for All Intra (AI) coding configuration for a wide range of video content.