First up, Gallium3D's video layer code and OpenMAX encode state tracker gained support for H.264 level support. H.264 encoding levels exposed are AVC Level 1/1b, 1.1, 1.2, 1.3, 2, 2.1, 2.2, 3, 3.1, 3.2, 4, 4.1, 4.2, 5, and 5.1. H.264 levels are a set of constraints for indicating encoder/decoder performance for a given profile in being able to meet a set of defined speeds for that level and all lower levels. Details on the H.264 levels are documented via Wikipedia.
This support was then wired up within the Radeon VCE code for exposing the actual base level rather than previously just exposing a 4.2 level for H.264.
Along with a few other Radeon video-related commits, the RadeonSI Gallium3D driver also received today sampling of 4:2:2 sub-sampled textures, which allow 4:2:2 video surfaces to work within VDPAU. On the video decode side with Radeon UVD, VC-1 simple/main was disabled for UVD2 over being broken.