Transform skip residual coding for the versatile video coding standard

The development of the emerging Versatile Video Coding (VVC) standard was motivated by the need of significant bit-rate reductions for natural video content as well as content for different applications, such as computer generated screen content. The signal characteristics of screen content video are different to the ones of natural content. These include sharp edges as well as at areas of the same color. In block-based hybrid video coding designs, as employed in VVC and its predecessors standards, skipping the transform stage of the prediction residual for screen content signals can be beneficial due to the different residual signal characteristics. In this paper, a modified transform coefficient level coding tailored for transform skip residual signals is presented. This includes no signaling of the last significant position, a coded block ag for every subblock, modified context modeling and binarization as well as a limit for the number of context coded bins per sample. Experimental results show bit-rate savings up to 3.45% and 9.55% for two different classes of screen content test sequences coded in a random access configuration.