Residual coding for transform skip mode in versatile video coding

The support for screen content coding has received more attention with the latest development in video compression, the upcoming Versatile Video Coding (VVC) standard. Among the dedicated screen content coding tools, the transform skip mode (TSM) represents a promising approach for improving the coding efficiency at a low impact on implementation complexity. In this work, we present a dedicated residual coding for transform blocks coded in TSM. Due to the lack of the energy compaction of the transform, the quantization indexes for blocks coded in TSM have different statistical properties, which can be exploited in the entropy coding. Our coding experiments with screen content sequences yielded bit-rate savings of 3.9% for intra-only coding and 2.8% for typical random access configurations.