On Extended Transform Partitions for the Next Generation Video CODEC

AV1, AOMedia's royalty free codec, has enjoyed a great amount of success since its 2018 release. It currently achieves 31% BDRATE gains over VP9, and is on its way to becoming YouTube's default codec. Although the industry is currently focused on the implementation and optimization of AV1, AOMedia Research continues to develop new coding tools that deliver higher coding gains within acceptable complexity bounds. Here, we focus on improving transform coding. While AV1 has made great strides in transform coding over VP9, the residue signal still consumes a large portion of the bitstream. In this paper, we describe a more flexible transform partitioning scheme, which will allow the next generation codec to more efficiently target areas in the residue signal with high energy, leading to better residue compression.