JVET-P0574 AHG18: BDPCM residual coding for lossless coding [H. Jang, J. Choi, J. Nam, S. Kim, J. Lim (LGE)]
In VVC, the transform_skip_flag is inferred to be 1 when the current CU is BDPCM coded block, and transform skip residual coding is used. Since transform skip mode and the BDPCM mode are not supported for chroma block, regular residual coding is used for chroma block. This contribution proposes to use regular residual coding pass for BDPCM coded block when lossless mode is engaged so that unified residual pass is used for lossless coded block. The experimental result shows 0.05%, 0.05% for AI, 0.04%, -0.01% for RA and 0.070%, 0.03% for LDB Bd-rate change for SCC and TGM respectivly. Over anchor which is initial lossless software of AhG18 with bugfix for BDPCM lossless.
This seems to be similar as JVET-P0082, but gains are somewhat lower. Conceptionally, it is not desirable to make the selection depending in various other coding modes. Not obvious what the benefit is.