Direct Delta Mush (DDM) is a high-quality, direct skinning method with a low setup cost. However, its storage and run-time computing cost are relatively high for two reasons: its skinning weights are 4 × 4 matrices instead of scalars like other direct skinning methods, and its computation requires one 3 × 3 Singular Value Decomposition per vertex. see this PDF.
see this video for SIGGRAPH 2021 Presentation: Direct Delta Mush Skinning Compression with Continuous Examples
